CA1216704A - Binder and refractory compositions and methods - Google Patents
Binder and refractory compositions and methodsInfo
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- CA1216704A CA1216704A CA000449376A CA449376A CA1216704A CA 1216704 A CA1216704 A CA 1216704A CA 000449376 A CA000449376 A CA 000449376A CA 449376 A CA449376 A CA 449376A CA 1216704 A CA1216704 A CA 1216704A
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- colloidal silica
- binder composition
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Abstract
ABSTRACT OF THE DISCLOSURE
Binder, filler, and refractory compositions and methods of using and making these compositions are dis-closed. The binder composition comprises colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from P, S, B and N and which stabilizes the binder composition against self-gelling. The colloidal silica and the liquid material are present in a ratio by weight of from about 1:12 to about 75:1 respectively. The liquid material has at least about 20% by weight SiO2. The colloidal silica contains at least about 15% by weight SiO2. The solvent and the organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase.
Binder, filler, and refractory compositions and methods of using and making these compositions are dis-closed. The binder composition comprises colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from P, S, B and N and which stabilizes the binder composition against self-gelling. The colloidal silica and the liquid material are present in a ratio by weight of from about 1:12 to about 75:1 respectively. The liquid material has at least about 20% by weight SiO2. The colloidal silica contains at least about 15% by weight SiO2. The solvent and the organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase.
Description
The present invention relates to a binder com-position for bonding molds, shapes, forms, etc. The invention also relates -to refractory molds, shapes and forms incorporating such a binder and to methods of 5 producing and using the binder and refractory compositions.
Alkyl silicates and colloidal sillca sols, among others, are two of the kinds of materials that have been used in binder compositions in preparing investment casting molds and other refractory molds, shapes and 10 forms. Attempts have been made to combine these two materials to obtain the advantageous properties of each while minimizing the less desirable aspects. For example, ethyl silicate provides high refractoriness and can be quickly chemically hardened or air hardened, but it 15 provides low bond strength and limited s-tability in refractory slurries. Colloidal silica sols, on the other hand, provides high bond streng-th and good slurry stabil-ity but cannot be chemically gelled to a single phase and is only slowly air hardened.
In U.S. Patent No, 3,961,968 a hybrid system of alkyl silicate and colloidal silica is disclosed in which a binder composition including both alkyl silicate and colloidal silica is produced by using various solvents including alcohols, ethylene glycol monoethers and 25 diglycol die-thers. This binder composition provided a desirable hybrid binder product when gelled, and at low ethyl silicate levels of about 8% a stable binder composition can be prepared which can be gelled -to a single phase. On the other hand, the hybrid binder cloes 30 not have good long term stability when higher ethyl silicate concentrations are employed, i.e., the binder of a higher ethyl silicate concentration gels by ltself after a short period of time without the addition of any gelllng agent. Since higher ethyl silicate levels provi.de certain 35 desi.rable characteristics for binder and refractory compositions, it would be desirable to provi.de a composition which is stable against self-gellation bu-t also which includes high amounts of ethyl silicate and which gels on command to a single phase.
An improvement on the hybrid binder system of lJ.S. Patent No. 3,961,968 is disclosed in U.S. Patent 5 No. 4,289,803 in which phosphoric acid is included in the hybrid alkyl silicate/colloidal silica binder composit:on to produce a phosphosilica-te composition, which is clis-closed as enhancing mold strength and refractoriness of the binder composition. The binder composJtions or U.S.
10 Patent No. 4,289,803 are stable at low ethyl silicate levels but not at high ethyl silicate levels.
It has now been found that a binder compositlon can be provided which has long term stability to self-gellation, which can include high amounts of alkyl 15 silica-te and which gells, stiffens and sets predic-tably on command at room temperature by heating or by addin~ a chemical gelling agent. By gelling on command, we mean -that the binder composition can be caused to ~el and set within about 2 minu-tes, preferably about 30 seconds to 20 l minute by addition of a suitable gelling agen-t. These characteristics are provided by a composition in accor-dance wi-th the presen-t invention comprising colloiclal silica, a liquid material con-taining Si-OH aroups.
solvent which is capable of solubilizing the 1iquid 25 material containing Si-OH groups ar;d -the colloidal sllica, and at least one apro-tic, non-ionic, non-metallic, orqanic compound which contains at least one element selected from the group consisting o~ phosphoxus, sulfur, boxon, nitrogen (identified hereinafter as P, S, B, N), and mixtures thereof 3~ and which stabilizes the binder composition agalrlst self-gelling. The colloidal silica and the l:iquid materlal containing Si-OH groups are present in a ratio by weiaht of from about 1:12 to about 75:1, e.g., from about 1:10 to about lO:1, respectively. The liquid material containing 3sSi-OH groups con-tains at least about 20% by weight SiO~, and the colloidal silica contains at least about 15~
weight of SiO2. The solvent and the aprotic organlc compound are present in amounts sufficient to solubilize .'i~A ~ a 7~
the colloidal silica and the liquid material containing Si-OH groups, to provide a binder composition which is stable against self-gellation, and to provide a hinder composition which gels to a single phase.
This binder composition can be mlxed ~r~lth refractory filler, i.e., larger aggregate and/or fine powders, to provide refractory cornpositions, which when gelled can be used, for example, as investment casting molds, as mold surface coatings, as refractory shapes, as 10 refractory foams, as a parting agent for stools in the making of ingots in the steel industry, as a paint contain-ing, e.g., Zn, for salt/brine resistant paints for shios, as a binder in combination with sand to fill holes quickly, for example, in an airport runway, as a binder 15 for the tiles on the heat resistant surfaces of reentry rockets or ships, and as a component of a furan resin binder system. The binder and filled compositions of the invention provide a combination of very desirable proper-ties to industry in that the compositions are stable 20 against self-gelling for long periods of time, but they can include high alkyl silicate conten-ts and can be made to gel on command to a single phase. Thus, the composi-tions of the present invention can be packaged for later use in predetermined concentrations to provide refractory 25 and binder composition of advantageous and known character-istics, e.g., dimensional and strength characteristics.
The compositions of the invention can also include organic compounds wh:ich decompose to provide for example boron or phosphorus oxides, thus providing an added refractory on 30 the molecular level which become part of the chemical and physical structure of the gelled composition.
In one embodiment of the present invention, the binder composition prepared therefrom comprises from about l to about 60% by weight, more preferably from abou-t 2 to 35 about 40%, e.g., from about 5 to about 40% by weight of ethyl silicate which has been hydrated and which conta~ns from about 28 to about 60% by weight of SiO2; from about 5 7~
to abou-t 75% by weight, more preferably from about =, to about 60%, e.g., from about 5 to about 40% by weiqht of colloidal silica containing from about 15 to about 60~ J
weight of SiO2; from about .5 to about 50% by weight, more 5preferably from about 1 to about 20%, e.g., from about .~
to about 10% by weight of dimethyl methyl phosphonate; and from about 10 to about 93.5% by weight, more preferably from about 20 to about 60%, e.g., from about 20 to about 55% by weight of a solvent selected from diethylene glycol lOmonoethyl ether, propylene glycol monomethyl ether or propylene glycol monopropyl ether.
As noted above, the binder composition of the present invention includes as its basic elements a llquid material containing Si-OH groups, colloidal silica, an 15appropriate solvent for -the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of P, S, B, N, and mixtures thereof and which stabilizes the binder 20compos:ition against self-gelling.
Any of the conventional liquid materlals contain-ing Si-OH groups known in the art for binder compositions can be employed in the presen-t invention. Preferably, the liquid materials are silicate esters, e.g., alkyl silicate 25materials, which have been hydrated. Such liquld materials should contain at least about 20% by weight Si02, and more preferably, from about 28% to about 60% by weigh-t of Si02.
Suitable liquid materials containing Si-OH groups include organooxysilanes (orthosilicic acid esters), and 30 poly(organooxysiloxanes) (polysilicic acid esters) which have been hydrolyzed, see, for example, Chap-ter 11 of "Chemistry and Technology of Silicones" by Walter Moll, Academic Press, 1968. The liquid materials can be simple molecules, but are usually polymeric in nature. Examples 35 of some commercially available alkyl silicates suitable for use in the present invention include Ethyl Silicate 40 available from Stauffer Chemical Company and other ethyl and propylsilicates available from Stauffer Chemical Company, Kay-Fries, Inc., and Union Carbide Corporation.
Any conventional colloidal silica can be employed in the present invention, including basi.c si.lica 5sols and acidic silica sols. Since the addition of base can upset the stability of the hydrolyzed alkyl si.licates if the pH is maintained for too long a per;od at about pH 5-7, -the use of basic silica sol must be carefully performed so that the pH of composition resulting from the 10 addition of the basic silica sol to th~ hydrolyzed alkyl silicate does no-t cause gellation of the hydrolyzed alkyl silicate and -therefore of the binder composition as a whole. Preferably, -the colloidal silica contains at least about 15% by weight of Si02, and more preferably, from l5abou-t 15% to about 60% by weight SiO2. Examples of suitable commercial colloidal silica compositi.ons include Nalcoag*1129 and Nal.coa~ 1034-A ~which are water based colloidal sili.ca sols) available from Nalco Chernical Company, Nyacol*2034DI available from Nyacol Corporation, 20and Ludox*LS available from E.I. du Pont de Nemors and Company. Acidic silica sols and si.lica sols in which the particles themselves are non-charged are preferred for us~
in the present invention.
A solvent is used in the composition of the 25present invention which will solubilize both the liqui.d material containing Si-OH groups and -the colloidal silica.
A preferred group of solvents are the water-miscible organic solvents, especially aliphatic alcohols having from 1 to 4 carbon atoms and glycol ethers. Examples of 30suitable solvents include ethanol, isopropanol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, and diethylene glycol monoethyl ether. Propylene glycol monome-thyl ether is particularly preferred in situations calling for a high volatility solvent, while 35diethylene glycol monoethyl ether is preferred for situati.ons requiring lower volatility solvents.
*trade marks The binder composition of the present invent-on also includes at least one aprotic, non-ionic, non-metallic organic compound which contains at least one element from the group consisting of P, S, B, ~, and 5 mix-tures thereof and which stabilizes the binder composi-tion against self-gelling. The organic compounds are preferably liquid at room temperature. The oraanic portions of the molecules are not critical so long as the organic compound along with -the solvent solubilizes the lO colloidal silica and the licluid material containing Si-OH
groups and results in a binder composition which is stable against self-gellation and which gels to a single phase.
In this regard, it has been found that organometallic compounds in general are probably too ionic in nature or 15 too insoluble to be suitable for use in the invention.
Likewi.se, protic materials such as bu-tyl acid phosphate or materials such as trimethyl phosphi-te (which ac-ts as a fairly strong Lewis base) are not sui.table for use in the i.nvention. Sui.table P containing organic compounds for use 20 in the present invention include, for example, fully esterified phosphate, pyrophosphate, and phosphonate esters. The B containing organic compounds suitable for use in the invention include, for example, fully esterl-fied borate and pyroborate esters. Suitable S containing 25 organic compounds include, for example, dialkyl or diaryl sulfoxides, while sulfate esters may be -too ionic in nature to be suitable. Dialkyl or diaryl amides of alkanoic acids are examples of organic compounds cor.tain-ing N which would be suitable for use in the present 30 invention. Preferably, the organic portions of the compounds are alkyl straight or branched chain groups containing from l to 6 carbon atoms, or are aryl groups containing 6 to 8 carbon atc,ms, e.g., phenyl. Preferred organic compounds are the organic compounds con-tai.ninq P
35 which when oxidized results in useful refractory oxi.des thereof. Examples of suitable organic compounds containinc~
P, B, S and/or N include dimethyl methyl phosphon~te 7 ~ ~
(DMMP), triethyl phosphate, tributyl borate, dimethyl sulfoxide and dimethyl formamide. It is believed that ~ne organic compound stabilizes the binder composition by inhibiting self-gellati.on while still allowing gelli.ng t~,y 5use of a gelling agent or by drying.
The binder composi-tion of the invention contain-ing DM~P has been found to be par-ticul.arly advantageous. A
binder composition containing 21So by weiyht Ethyl Silicate 40, 4.'7% by weight wa-ter, 37% by wei.ght diethyl-10 ene glycol monoethyl e-ther, 30% by weight Nalcoag 1129, 7.2% by weight DMMP, and 0.1% by weight concentrated HCl prepared in accordance with the present, invention has been found by the conventional pyrometric cone equivalen-t, (PCE) test to provide a PCE value of 32-33, whereas a bi.nder 15 composition without the DMMP only provided a PC~ value of appro~ima-tely 2~. Similar PCE values are expected for other compositions of the inven-t-,ion. This charac-teristic of the bi.nder composi-tion of the present i.n~entioi-. .is considered hiyhly advantageous because i-t means that the 20 binder composition of the invention can be used a-t hi.gher -temperatures than conventional binder compositi.ons withcut DMMP. For example, this charac-teristic makeci the binder composition of -the invention suitable for use in casting me-tal alloys requiring molten temperatures above 30GO or 25 even 3100F.
The binder composition of -the present invent,i.on contains the colloidal silica and -the li.quid material containing Si-O~I groups in a ratio by weight of from about 1:12 to about 75:1, e.g., from about 1:10 to about 10:1 30 respectively. Preferably, the bi.nder compositi.on contalns from about 1 to about 60% by weight, e.g~, from about 2 to about 60% by weight of the liquid material cont,ai.nlng Si-OH groups, and more preferably, from about 2 to about 40% by weight, e.g., from about 5 to about 40%. The binder 35 composition also preferably con-tains from about 5 to about 75% by weight, e.g., from about 5 to about 55/0 by weiqht.
colloidal silica, and more preferably, from about 5 to ~z~
60% by weight, e.g., from abou-t 5 -to about 40%.
It has also been found that very good results are obtained with rela-tively low amounts of the liquid material containing Si-OH qroups. For example, a 5 composition prepared from a mixture of primary components consistiny essentially of 4.1% by weiqht ethvl silicate 40, 4.1% by weight DMr~P, 36.3% by wei-lht propylene glycol monomethyl ether, and 55.3% by weight of Nyacol 2034 (colloidal silica with 34% SiO2 and 66% H20), 10 when used as a wash for a sand mold provided a heavy steel casting surface as good as an "as cast" surface. Because of the low amounts of silicate ma-terial employed, such compositions are easy to manufac-ture and are also very economical. Although it can be found that the llquid 15 material containing Si-OH groups is a necessary part of the binder composition of the invention, the lower percentage weight limit of such liquid material has not been determined exactly. On the other hand, because 4.1%
by weight performs well, it is believed -that a weiqht 20 percentage as low as 1% and perhaps even lower can be employed while still providing good results as, e.g., an investment casting wash.
The solvent and the organic compound are present in -the binder composition of the present invention in 25 amounts sufficient to solubilize the colloidal silica and the liquid material containing Si-OH groups, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a slngle phase. Preferably, -the binder composition is stable 30 against self-gellation for at leas-t about 3-9 months, more preferably at least about 1 year or more. Sultable concen-trations for the aprotic organic compounds in the binder compositions of -the present invention include from ahout .5% to about 50% by weight of the composition, and prefer-35 ably, from about 1% to about 20% by weight, e.g., fromabout 5 to about 12%. Preferably, the composition of the present invention includes from about 10% to about 93.5~
7~
g by weight, e.g., from about 20 to about 55% by wei~ht of solvent. Typically, when more aprotic organic compound is employed less solvent and more preferably from ahout ~n ~"
about 60% is necessary.
It is sometimes advantaqeous to include a thickening agent in preparing refractory compositions with the binder composition of the invention. Preferably, minimum amount of -thickening agent is employed so as not - -to upset the system. Typically, amounts lower than about 10 0.1% by weight, preferably from about 0.01 to about 0.1~
by weight of thickening agent are employed in preparing refractory compositions. Suitable thickening agerlts include conventional non-ionic thickening aqents such dS
the hydroxyalkyl cellulose materials, for examp1e, 15 hydroxypropyl cellulose, e.g., Klucel*H available froln Hercules. The thickening agent impar-ts a soft sett]~ng charac-teristic to the refractory composition so that the settling of -the added refractory, e.g., zircon powder, from the composition is inhibited.
Various other materials can be included in the binder composition of the present invention, e.q., the reaction products from the hydration of the alkyl silicate, surfactants, and viscosity modifiers to provide a "paint" to which filler particles can be added to 2S provide refractory coatings. The amounts and types of such other materials vary according to the purpose of the additive and the ultimate application of the bincier composi-tion.
The binder composition can be prepared by arly 30 method which will result in a stabilized mixture or composition containing these four basic elements. ]~n one method, a strong inorganic acid such as concentrated sulfuric acid or hydrochloric acid is mixed with water.
Preferably, the water is distilled and deionized, and the 35 amount of water present is about the amount needed to hydrate the ethyl silicate, i.e., large excesses of water are avoided. The acid should be present so that the final *trade mark t~
pH of the binder composition is at a pH of from about 1 ~o about 3. An appropriate solvent for the alkyl s;licate -nc~
the colloidal silica is then added, e.g., lso~ropyl alcohol, die-thylene glycol monoethyl ether and~'or 5 propylene glycol monomethyl e-ther. This mixture is agitated and an alkyl silicate such as ethyl silicate is then added slowly and the temperature is controlled, preferably between 15 C. and 31 C. During thi,s part of the reaction, the alkyl silicate is being hydrated. This 10 hydration reaction is exothermic and therefore can be monitored by use of a thermometer. When the system stops giving off heat, the reaction is essentially complete.
However, in this method the hydrated al,kyl silicate solution is preferably allowed to "rest" for a period of 15 time, e.g., 24 hours or lon~er, to stabilize -the hydrated alkyl silicate thereby produced. After this period of rest, the organic compound, preferably DMMP, is added w]th agitation and then over a period of time the colloidal silica is slowly added. This method results ln a very 20 stable binder composition.
In another embodiment, -the silica-te ester, the concentra-ted acid, the solvent and the aprotic organic compound can be placed in a reactor and the colloidal silica can be added slowly to -the above reactants, e.g., 25 by using a glass funnel with a petcock. Preferably, the reaction mixture is formed by blending the s-ili,cate ester with the solvent and/or aprotic organic compound and adding the acid thereto. The acid acts as a catalyst for the hydration reaction and i,s present in a suffic-ient 30 amount to provide a final pH of from about ~ to abo~t ~, for the resulting binder composition. The colloidal sil?ca provides substantially all of -the water necessary to hydrate the silicate ester. Preferably, the reactor ~s capable of being temperature controlled, e.~ a~,er 35 cooled. The temperature is preferably maintained frvm about 15 to about 31 C, and during the entire reaction, the reactants are agitated, e.g., with a mechanical 7.;~
s-tirrer. The colloidal silica is dripped into the re-:c-tants at a slow rate, e.g., to provide a reaction ti~ne from 1-2 hours. This assures hydration of the 31'.~yl silicate without gelling the resulting binder compos~tion.
5 In the initial stages of the reaction, the colloidal silica is hydrated. This hydration usually occurs in the first 25% of the total reaction time. Again, during the hydration period an exotherm usually occurs which is readily discernable by using a thermometer. Thus, the 10 temperature of the reactants can be used to follow the hydration reaction.
The binder composition could also be prepared by starting with a hydrated alkyl silicate and just adding the aprotic organic compound and colloidal silica thereto 15 as described above. One such hydrated alkyl silicate is available from Stauffer Chemical Company under the name Hydrated Ethyl Silicate Type E-5.
The binder composition of the present invention can be used alone, for example, as a corrosion reslstant 20 adhesive, or can be used to prepare refractory composi-tions for numerous applications, e.g., as investment casting molds, as a refractory coating for the plastic film in the well-known V-process, as coatings for sand molds, as refractory shapes or as refrac-tory foams. These 25 refractory compositions basically comprise the binder compositlon described above and filler particles, e.
larger aggrega-te and/or fine powders.
Additionally, the refractory compo:,itions can include a predetermined quantity of an additive selected 30 from -the group consisting of polyvinyl acetate, polyvinyl alcohol, gums, and clay for green streng-th. A surfactant can also be included for wetting refractory powders during the preparation and use of the compositions for coating surfaces, e.g., of sand molds.
The selection of the filler particles depends on the ultimate use to be made of the refractory composition as is conventional in the ar-t. The filler Particles can 7~*
change and improve many of the properties of the binder including the refractoriness, stability, crystallization, strength, thermal shock resistance, permeability, and toughness. Thus, if an investment casting mold is being 5prepared, combinations of fine powders and larger agqre-gate will be most likely employed as is conventional in the art, while powdered filler particles, for example, zircon, ground to 100 mesh or finer will most like]y -to be employed if a coating for -the surface of a sand mold is lO contempla-ted. Addition of graphite can provide a non-oxidizing type binder system for use, for example 7 in making Ti metal castings, where the molten Ti might normally be oxidized by the oxygen in the binder sys-tem.
Examples of suitable fil:Ler par-ticles include refractory 15 and non-refractory fillers. Examples of non-refractory fillers include polystyrene (e.g., beads), mica, talc, iron oxide and boric acid. Suitable refractory particles include zircon, silica, olivine, clay, alumina-silicate, graphite, fused silica, alurnina, chromite, fibrous-alumina 20 silicate, magnesia, or quartz. Combinations of -these fi]ler materials can also be used.
The filler par-ticles can be mixed with the binder composition of the present invention in any amount suitable to provide a composition for the desired purpose 25 as is conventional in the ar-t. Typically, -the filled compositions contain *rom about 5 to 50% by weight of the binder composition.
The binder composition and filled composition -in accordance with the present invention can be ~elled in any 30 conventional manner. For example, the binder and filled compositions can be gelled by employing a gelling agent such as ammonium hydroxide, MgO or ammonia gas. The compositions can also be gelled by drying as is conven-tional in the art.
The binder compositions of the present invention bond together, without heat, the filler particles. The filled compositions of -the invention are very advantageous because they can be gelled on command, but are themselves stable against gellation and can be employed in many applications in either fired or non-fired conditions.
The filled compositions can be refractory scompositions gelled in the desired shape, e.g., by the '~lost wax process" or in the form of a refractory shape or foam as described below. The gelled, shaped refractory composition can be used as is or can be fired at a temperature sufficient to oxldize the aprotic organic lOcompounds therein to complex refractory oxides and/or volatilized materials.
As noted above, the refractory compositions of the invention can be used in conventional processes for preparing investment casting molds, coatings for molds 15such as sand molds, refractory shapes, and refractory foams. These processes are conventional in the art and need not be detailed here. However, since the present invention can be employed in such process, they are briefly discussed below as they rela-te to the invention.
A number of important characteristics are important in investment casting molds:
tl) They should be able to withstand high temperatures, since some commercially important metals become fluid at temperatures above about 1000F. and iron and steel above 2000F.
Alkyl silicates and colloidal sillca sols, among others, are two of the kinds of materials that have been used in binder compositions in preparing investment casting molds and other refractory molds, shapes and 10 forms. Attempts have been made to combine these two materials to obtain the advantageous properties of each while minimizing the less desirable aspects. For example, ethyl silicate provides high refractoriness and can be quickly chemically hardened or air hardened, but it 15 provides low bond strength and limited s-tability in refractory slurries. Colloidal silica sols, on the other hand, provides high bond streng-th and good slurry stabil-ity but cannot be chemically gelled to a single phase and is only slowly air hardened.
In U.S. Patent No, 3,961,968 a hybrid system of alkyl silicate and colloidal silica is disclosed in which a binder composition including both alkyl silicate and colloidal silica is produced by using various solvents including alcohols, ethylene glycol monoethers and 25 diglycol die-thers. This binder composition provided a desirable hybrid binder product when gelled, and at low ethyl silicate levels of about 8% a stable binder composition can be prepared which can be gelled -to a single phase. On the other hand, the hybrid binder cloes 30 not have good long term stability when higher ethyl silicate concentrations are employed, i.e., the binder of a higher ethyl silicate concentration gels by ltself after a short period of time without the addition of any gelllng agent. Since higher ethyl silicate levels provi.de certain 35 desi.rable characteristics for binder and refractory compositions, it would be desirable to provi.de a composition which is stable against self-gellation bu-t also which includes high amounts of ethyl silicate and which gels on command to a single phase.
An improvement on the hybrid binder system of lJ.S. Patent No. 3,961,968 is disclosed in U.S. Patent 5 No. 4,289,803 in which phosphoric acid is included in the hybrid alkyl silicate/colloidal silica binder composit:on to produce a phosphosilica-te composition, which is clis-closed as enhancing mold strength and refractoriness of the binder composition. The binder composJtions or U.S.
10 Patent No. 4,289,803 are stable at low ethyl silicate levels but not at high ethyl silicate levels.
It has now been found that a binder compositlon can be provided which has long term stability to self-gellation, which can include high amounts of alkyl 15 silica-te and which gells, stiffens and sets predic-tably on command at room temperature by heating or by addin~ a chemical gelling agent. By gelling on command, we mean -that the binder composition can be caused to ~el and set within about 2 minu-tes, preferably about 30 seconds to 20 l minute by addition of a suitable gelling agen-t. These characteristics are provided by a composition in accor-dance wi-th the presen-t invention comprising colloiclal silica, a liquid material con-taining Si-OH aroups.
solvent which is capable of solubilizing the 1iquid 25 material containing Si-OH groups ar;d -the colloidal sllica, and at least one apro-tic, non-ionic, non-metallic, orqanic compound which contains at least one element selected from the group consisting o~ phosphoxus, sulfur, boxon, nitrogen (identified hereinafter as P, S, B, N), and mixtures thereof 3~ and which stabilizes the binder composition agalrlst self-gelling. The colloidal silica and the l:iquid materlal containing Si-OH groups are present in a ratio by weiaht of from about 1:12 to about 75:1, e.g., from about 1:10 to about lO:1, respectively. The liquid material containing 3sSi-OH groups con-tains at least about 20% by weight SiO~, and the colloidal silica contains at least about 15~
weight of SiO2. The solvent and the aprotic organlc compound are present in amounts sufficient to solubilize .'i~A ~ a 7~
the colloidal silica and the liquid material containing Si-OH groups, to provide a binder composition which is stable against self-gellation, and to provide a hinder composition which gels to a single phase.
This binder composition can be mlxed ~r~lth refractory filler, i.e., larger aggregate and/or fine powders, to provide refractory cornpositions, which when gelled can be used, for example, as investment casting molds, as mold surface coatings, as refractory shapes, as 10 refractory foams, as a parting agent for stools in the making of ingots in the steel industry, as a paint contain-ing, e.g., Zn, for salt/brine resistant paints for shios, as a binder in combination with sand to fill holes quickly, for example, in an airport runway, as a binder 15 for the tiles on the heat resistant surfaces of reentry rockets or ships, and as a component of a furan resin binder system. The binder and filled compositions of the invention provide a combination of very desirable proper-ties to industry in that the compositions are stable 20 against self-gelling for long periods of time, but they can include high alkyl silicate conten-ts and can be made to gel on command to a single phase. Thus, the composi-tions of the present invention can be packaged for later use in predetermined concentrations to provide refractory 25 and binder composition of advantageous and known character-istics, e.g., dimensional and strength characteristics.
The compositions of the invention can also include organic compounds wh:ich decompose to provide for example boron or phosphorus oxides, thus providing an added refractory on 30 the molecular level which become part of the chemical and physical structure of the gelled composition.
In one embodiment of the present invention, the binder composition prepared therefrom comprises from about l to about 60% by weight, more preferably from abou-t 2 to 35 about 40%, e.g., from about 5 to about 40% by weight of ethyl silicate which has been hydrated and which conta~ns from about 28 to about 60% by weight of SiO2; from about 5 7~
to abou-t 75% by weight, more preferably from about =, to about 60%, e.g., from about 5 to about 40% by weiqht of colloidal silica containing from about 15 to about 60~ J
weight of SiO2; from about .5 to about 50% by weight, more 5preferably from about 1 to about 20%, e.g., from about .~
to about 10% by weight of dimethyl methyl phosphonate; and from about 10 to about 93.5% by weight, more preferably from about 20 to about 60%, e.g., from about 20 to about 55% by weight of a solvent selected from diethylene glycol lOmonoethyl ether, propylene glycol monomethyl ether or propylene glycol monopropyl ether.
As noted above, the binder composition of the present invention includes as its basic elements a llquid material containing Si-OH groups, colloidal silica, an 15appropriate solvent for -the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of P, S, B, N, and mixtures thereof and which stabilizes the binder 20compos:ition against self-gelling.
Any of the conventional liquid materlals contain-ing Si-OH groups known in the art for binder compositions can be employed in the presen-t invention. Preferably, the liquid materials are silicate esters, e.g., alkyl silicate 25materials, which have been hydrated. Such liquld materials should contain at least about 20% by weight Si02, and more preferably, from about 28% to about 60% by weigh-t of Si02.
Suitable liquid materials containing Si-OH groups include organooxysilanes (orthosilicic acid esters), and 30 poly(organooxysiloxanes) (polysilicic acid esters) which have been hydrolyzed, see, for example, Chap-ter 11 of "Chemistry and Technology of Silicones" by Walter Moll, Academic Press, 1968. The liquid materials can be simple molecules, but are usually polymeric in nature. Examples 35 of some commercially available alkyl silicates suitable for use in the present invention include Ethyl Silicate 40 available from Stauffer Chemical Company and other ethyl and propylsilicates available from Stauffer Chemical Company, Kay-Fries, Inc., and Union Carbide Corporation.
Any conventional colloidal silica can be employed in the present invention, including basi.c si.lica 5sols and acidic silica sols. Since the addition of base can upset the stability of the hydrolyzed alkyl si.licates if the pH is maintained for too long a per;od at about pH 5-7, -the use of basic silica sol must be carefully performed so that the pH of composition resulting from the 10 addition of the basic silica sol to th~ hydrolyzed alkyl silicate does no-t cause gellation of the hydrolyzed alkyl silicate and -therefore of the binder composition as a whole. Preferably, -the colloidal silica contains at least about 15% by weight of Si02, and more preferably, from l5abou-t 15% to about 60% by weight SiO2. Examples of suitable commercial colloidal silica compositi.ons include Nalcoag*1129 and Nal.coa~ 1034-A ~which are water based colloidal sili.ca sols) available from Nalco Chernical Company, Nyacol*2034DI available from Nyacol Corporation, 20and Ludox*LS available from E.I. du Pont de Nemors and Company. Acidic silica sols and si.lica sols in which the particles themselves are non-charged are preferred for us~
in the present invention.
A solvent is used in the composition of the 25present invention which will solubilize both the liqui.d material containing Si-OH groups and -the colloidal silica.
A preferred group of solvents are the water-miscible organic solvents, especially aliphatic alcohols having from 1 to 4 carbon atoms and glycol ethers. Examples of 30suitable solvents include ethanol, isopropanol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, and diethylene glycol monoethyl ether. Propylene glycol monome-thyl ether is particularly preferred in situations calling for a high volatility solvent, while 35diethylene glycol monoethyl ether is preferred for situati.ons requiring lower volatility solvents.
*trade marks The binder composition of the present invent-on also includes at least one aprotic, non-ionic, non-metallic organic compound which contains at least one element from the group consisting of P, S, B, ~, and 5 mix-tures thereof and which stabilizes the binder composi-tion against self-gelling. The organic compounds are preferably liquid at room temperature. The oraanic portions of the molecules are not critical so long as the organic compound along with -the solvent solubilizes the lO colloidal silica and the licluid material containing Si-OH
groups and results in a binder composition which is stable against self-gellation and which gels to a single phase.
In this regard, it has been found that organometallic compounds in general are probably too ionic in nature or 15 too insoluble to be suitable for use in the invention.
Likewi.se, protic materials such as bu-tyl acid phosphate or materials such as trimethyl phosphi-te (which ac-ts as a fairly strong Lewis base) are not sui.table for use in the i.nvention. Sui.table P containing organic compounds for use 20 in the present invention include, for example, fully esterified phosphate, pyrophosphate, and phosphonate esters. The B containing organic compounds suitable for use in the invention include, for example, fully esterl-fied borate and pyroborate esters. Suitable S containing 25 organic compounds include, for example, dialkyl or diaryl sulfoxides, while sulfate esters may be -too ionic in nature to be suitable. Dialkyl or diaryl amides of alkanoic acids are examples of organic compounds cor.tain-ing N which would be suitable for use in the present 30 invention. Preferably, the organic portions of the compounds are alkyl straight or branched chain groups containing from l to 6 carbon atoms, or are aryl groups containing 6 to 8 carbon atc,ms, e.g., phenyl. Preferred organic compounds are the organic compounds con-tai.ninq P
35 which when oxidized results in useful refractory oxi.des thereof. Examples of suitable organic compounds containinc~
P, B, S and/or N include dimethyl methyl phosphon~te 7 ~ ~
(DMMP), triethyl phosphate, tributyl borate, dimethyl sulfoxide and dimethyl formamide. It is believed that ~ne organic compound stabilizes the binder composition by inhibiting self-gellati.on while still allowing gelli.ng t~,y 5use of a gelling agent or by drying.
The binder composi-tion of the invention contain-ing DM~P has been found to be par-ticul.arly advantageous. A
binder composition containing 21So by weiyht Ethyl Silicate 40, 4.'7% by weight wa-ter, 37% by wei.ght diethyl-10 ene glycol monoethyl e-ther, 30% by weight Nalcoag 1129, 7.2% by weight DMMP, and 0.1% by weight concentrated HCl prepared in accordance with the present, invention has been found by the conventional pyrometric cone equivalen-t, (PCE) test to provide a PCE value of 32-33, whereas a bi.nder 15 composition without the DMMP only provided a PC~ value of appro~ima-tely 2~. Similar PCE values are expected for other compositions of the inven-t-,ion. This charac-teristic of the bi.nder composi-tion of the present i.n~entioi-. .is considered hiyhly advantageous because i-t means that the 20 binder composition of the invention can be used a-t hi.gher -temperatures than conventional binder compositi.ons withcut DMMP. For example, this charac-teristic makeci the binder composition of -the invention suitable for use in casting me-tal alloys requiring molten temperatures above 30GO or 25 even 3100F.
The binder composition of -the present invent,i.on contains the colloidal silica and -the li.quid material containing Si-O~I groups in a ratio by weight of from about 1:12 to about 75:1, e.g., from about 1:10 to about 10:1 30 respectively. Preferably, the bi.nder compositi.on contalns from about 1 to about 60% by weight, e.g~, from about 2 to about 60% by weight of the liquid material cont,ai.nlng Si-OH groups, and more preferably, from about 2 to about 40% by weight, e.g., from about 5 to about 40%. The binder 35 composition also preferably con-tains from about 5 to about 75% by weight, e.g., from about 5 to about 55/0 by weiqht.
colloidal silica, and more preferably, from about 5 to ~z~
60% by weight, e.g., from abou-t 5 -to about 40%.
It has also been found that very good results are obtained with rela-tively low amounts of the liquid material containing Si-OH qroups. For example, a 5 composition prepared from a mixture of primary components consistiny essentially of 4.1% by weiqht ethvl silicate 40, 4.1% by weight DMr~P, 36.3% by wei-lht propylene glycol monomethyl ether, and 55.3% by weight of Nyacol 2034 (colloidal silica with 34% SiO2 and 66% H20), 10 when used as a wash for a sand mold provided a heavy steel casting surface as good as an "as cast" surface. Because of the low amounts of silicate ma-terial employed, such compositions are easy to manufac-ture and are also very economical. Although it can be found that the llquid 15 material containing Si-OH groups is a necessary part of the binder composition of the invention, the lower percentage weight limit of such liquid material has not been determined exactly. On the other hand, because 4.1%
by weight performs well, it is believed -that a weiqht 20 percentage as low as 1% and perhaps even lower can be employed while still providing good results as, e.g., an investment casting wash.
The solvent and the organic compound are present in -the binder composition of the present invention in 25 amounts sufficient to solubilize the colloidal silica and the liquid material containing Si-OH groups, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a slngle phase. Preferably, -the binder composition is stable 30 against self-gellation for at leas-t about 3-9 months, more preferably at least about 1 year or more. Sultable concen-trations for the aprotic organic compounds in the binder compositions of -the present invention include from ahout .5% to about 50% by weight of the composition, and prefer-35 ably, from about 1% to about 20% by weight, e.g., fromabout 5 to about 12%. Preferably, the composition of the present invention includes from about 10% to about 93.5~
7~
g by weight, e.g., from about 20 to about 55% by wei~ht of solvent. Typically, when more aprotic organic compound is employed less solvent and more preferably from ahout ~n ~"
about 60% is necessary.
It is sometimes advantaqeous to include a thickening agent in preparing refractory compositions with the binder composition of the invention. Preferably, minimum amount of -thickening agent is employed so as not - -to upset the system. Typically, amounts lower than about 10 0.1% by weight, preferably from about 0.01 to about 0.1~
by weight of thickening agent are employed in preparing refractory compositions. Suitable thickening agerlts include conventional non-ionic thickening aqents such dS
the hydroxyalkyl cellulose materials, for examp1e, 15 hydroxypropyl cellulose, e.g., Klucel*H available froln Hercules. The thickening agent impar-ts a soft sett]~ng charac-teristic to the refractory composition so that the settling of -the added refractory, e.g., zircon powder, from the composition is inhibited.
Various other materials can be included in the binder composition of the present invention, e.q., the reaction products from the hydration of the alkyl silicate, surfactants, and viscosity modifiers to provide a "paint" to which filler particles can be added to 2S provide refractory coatings. The amounts and types of such other materials vary according to the purpose of the additive and the ultimate application of the bincier composi-tion.
The binder composition can be prepared by arly 30 method which will result in a stabilized mixture or composition containing these four basic elements. ]~n one method, a strong inorganic acid such as concentrated sulfuric acid or hydrochloric acid is mixed with water.
Preferably, the water is distilled and deionized, and the 35 amount of water present is about the amount needed to hydrate the ethyl silicate, i.e., large excesses of water are avoided. The acid should be present so that the final *trade mark t~
pH of the binder composition is at a pH of from about 1 ~o about 3. An appropriate solvent for the alkyl s;licate -nc~
the colloidal silica is then added, e.g., lso~ropyl alcohol, die-thylene glycol monoethyl ether and~'or 5 propylene glycol monomethyl e-ther. This mixture is agitated and an alkyl silicate such as ethyl silicate is then added slowly and the temperature is controlled, preferably between 15 C. and 31 C. During thi,s part of the reaction, the alkyl silicate is being hydrated. This 10 hydration reaction is exothermic and therefore can be monitored by use of a thermometer. When the system stops giving off heat, the reaction is essentially complete.
However, in this method the hydrated al,kyl silicate solution is preferably allowed to "rest" for a period of 15 time, e.g., 24 hours or lon~er, to stabilize -the hydrated alkyl silicate thereby produced. After this period of rest, the organic compound, preferably DMMP, is added w]th agitation and then over a period of time the colloidal silica is slowly added. This method results ln a very 20 stable binder composition.
In another embodiment, -the silica-te ester, the concentra-ted acid, the solvent and the aprotic organic compound can be placed in a reactor and the colloidal silica can be added slowly to -the above reactants, e.g., 25 by using a glass funnel with a petcock. Preferably, the reaction mixture is formed by blending the s-ili,cate ester with the solvent and/or aprotic organic compound and adding the acid thereto. The acid acts as a catalyst for the hydration reaction and i,s present in a suffic-ient 30 amount to provide a final pH of from about ~ to abo~t ~, for the resulting binder composition. The colloidal sil?ca provides substantially all of -the water necessary to hydrate the silicate ester. Preferably, the reactor ~s capable of being temperature controlled, e.~ a~,er 35 cooled. The temperature is preferably maintained frvm about 15 to about 31 C, and during the entire reaction, the reactants are agitated, e.g., with a mechanical 7.;~
s-tirrer. The colloidal silica is dripped into the re-:c-tants at a slow rate, e.g., to provide a reaction ti~ne from 1-2 hours. This assures hydration of the 31'.~yl silicate without gelling the resulting binder compos~tion.
5 In the initial stages of the reaction, the colloidal silica is hydrated. This hydration usually occurs in the first 25% of the total reaction time. Again, during the hydration period an exotherm usually occurs which is readily discernable by using a thermometer. Thus, the 10 temperature of the reactants can be used to follow the hydration reaction.
The binder composition could also be prepared by starting with a hydrated alkyl silicate and just adding the aprotic organic compound and colloidal silica thereto 15 as described above. One such hydrated alkyl silicate is available from Stauffer Chemical Company under the name Hydrated Ethyl Silicate Type E-5.
The binder composition of the present invention can be used alone, for example, as a corrosion reslstant 20 adhesive, or can be used to prepare refractory composi-tions for numerous applications, e.g., as investment casting molds, as a refractory coating for the plastic film in the well-known V-process, as coatings for sand molds, as refractory shapes or as refrac-tory foams. These 25 refractory compositions basically comprise the binder compositlon described above and filler particles, e.
larger aggrega-te and/or fine powders.
Additionally, the refractory compo:,itions can include a predetermined quantity of an additive selected 30 from -the group consisting of polyvinyl acetate, polyvinyl alcohol, gums, and clay for green streng-th. A surfactant can also be included for wetting refractory powders during the preparation and use of the compositions for coating surfaces, e.g., of sand molds.
The selection of the filler particles depends on the ultimate use to be made of the refractory composition as is conventional in the ar-t. The filler Particles can 7~*
change and improve many of the properties of the binder including the refractoriness, stability, crystallization, strength, thermal shock resistance, permeability, and toughness. Thus, if an investment casting mold is being 5prepared, combinations of fine powders and larger agqre-gate will be most likely employed as is conventional in the art, while powdered filler particles, for example, zircon, ground to 100 mesh or finer will most like]y -to be employed if a coating for -the surface of a sand mold is lO contempla-ted. Addition of graphite can provide a non-oxidizing type binder system for use, for example 7 in making Ti metal castings, where the molten Ti might normally be oxidized by the oxygen in the binder sys-tem.
Examples of suitable fil:Ler par-ticles include refractory 15 and non-refractory fillers. Examples of non-refractory fillers include polystyrene (e.g., beads), mica, talc, iron oxide and boric acid. Suitable refractory particles include zircon, silica, olivine, clay, alumina-silicate, graphite, fused silica, alurnina, chromite, fibrous-alumina 20 silicate, magnesia, or quartz. Combinations of -these fi]ler materials can also be used.
The filler par-ticles can be mixed with the binder composition of the present invention in any amount suitable to provide a composition for the desired purpose 25 as is conventional in the ar-t. Typically, -the filled compositions contain *rom about 5 to 50% by weight of the binder composition.
The binder composition and filled composition -in accordance with the present invention can be ~elled in any 30 conventional manner. For example, the binder and filled compositions can be gelled by employing a gelling agent such as ammonium hydroxide, MgO or ammonia gas. The compositions can also be gelled by drying as is conven-tional in the art.
The binder compositions of the present invention bond together, without heat, the filler particles. The filled compositions of -the invention are very advantageous because they can be gelled on command, but are themselves stable against gellation and can be employed in many applications in either fired or non-fired conditions.
The filled compositions can be refractory scompositions gelled in the desired shape, e.g., by the '~lost wax process" or in the form of a refractory shape or foam as described below. The gelled, shaped refractory composition can be used as is or can be fired at a temperature sufficient to oxldize the aprotic organic lOcompounds therein to complex refractory oxides and/or volatilized materials.
As noted above, the refractory compositions of the invention can be used in conventional processes for preparing investment casting molds, coatings for molds 15such as sand molds, refractory shapes, and refractory foams. These processes are conventional in the art and need not be detailed here. However, since the present invention can be employed in such process, they are briefly discussed below as they rela-te to the invention.
A number of important characteristics are important in investment casting molds:
tl) They should be able to withstand high temperatures, since some commercially important metals become fluid at temperatures above about 1000F. and iron and steel above 2000F.
(2) The mold should also conform to specifi-cations which approach those normally encoun-tered with machine metal parts.
(3) The molds should faithfully reproduce the shape and dimensions of the pattern of the mold; and therefore the binder composition used in preparing the mold should have sufficient strength so that the refrac-tory composi,tion can withstand the physical handling forces from start to finish of the mold forming process.
(4) The mold should be able to be aener-ated qui.ckly at ambient temperatures with suffi-cient binder strength after forming to ~ithstand the dewaxing stresses encountered when the pattern is removed.
(5) The dewaxed mold should also be able to withstand long periods of storage under ambient conditions without deterioration.
These characteristics are provided by the binder and refractory compositions of the present lnvention. In particular, the refractory composi-tions of the present 10 invention can withstand temperatures of PCE 32-33 and have sufficient strength to also withstand the ~lost wax process" for preparing investment casting molds.
Investment casting molds are generally prepared by the "lost wax process". In this process, a wax mold is 15prepared in the shape desired for the ultimate metal casting. Binder is applied to this wax mold by dipping the mold into a refractory slurry such as a refractory composition of the invention. Filler particles such as refractory particles are then applied to the slurry 20coating on the wax mold and the binder com~osition is gelled. The wax mold is then again dipped into the refractory slurry, more filler particles applied, and the binder composition gelled again. These steps are repeated until the desired characteristics of -the refractory invest-25ment casting mold are achieved. Normally, -the size of the filler particles increases from the inside to -the outside of the casting mold.
The wax mold is then dewaxed by processes again conventional in the ar-t. The refractory slurry of the 30invention provides sufficient strength to -the mold to withstand the stresses during this dewaxing step.
The dewaxed investment mold prepared in accor-dance with the invention can be stored for long periods of time. It can then be used in a conventional investment 35casting process. During the casting process, the binder and refractory compositions must withs-tand even greater stresses.
7~'~
In preparing a fired investment mold, t'ne dewaxed investment mold is first fired to burn out temperatures of about 1800 F. This burn out accompllshes three things:
(1) it rids the mold cavi-ty of all residual organic matter;
(2) it oxidizes and recrystallizes all refractory materials to their most stable high temperature form; and (3) it heats the mold to decrease thermal shock from the molten metal during pour.
Thus, as is conventional in the art, due considera~lon must be given during formulation of the binder to compen-sate for the dimensional changes which take place within 15 the binder during the burnout period. Some mold failures are characterized by such things as frac-tures, warpage, passage restrictions, low strengths and perrneability problems. To some degree, these failures have been traced to refractory binders. 1`he present invention provides good 20 binder reliability.
In order to avoid the above problems, -the binder in the investment mold should withstand high temperature handling when the mold, which is normally at about 1800F., is moved from the burnout position~ which is 25 generally upside down, to the casting position, which is right side up. All of this requires ri~idi-ty under conditions which are prone towards plas-ticity because of glass formation.
The binder should also withstand the rigors of 30 the pour. This means that the mold cavity should be able to capture molten metal as it falls from the furnace or ladle and to withstand the two shocks encountered in such a fall. Thus, the binder should be able to withstand the mechanical shock of being hit with a falling mass having a 35 specific gravity of from 5 to 9 and the thermal shock of being hit with a very hot mass having a temperature difference of up to about 1000F or greater.
The binder should further decrepitate after ~,he metal solidifies so as not to place any undue mechanical stresses on the hot metal during its cooling stage, ,when it is shrinking and is prone to hot tears from the 5 stronger molding media.
The binder should not adhere to the metal surfaces after shake-out. If it does, the castina will have such defects as burn-ins, penetrations or other surfaces blemishes. In other words, it should break awa~
~o clean.
The binder and refractory compositions of the present ,invention provide these desirable results for investment casting molds.
In the case of sand mold casting, si,milar but 15 less stringent mold re~uirements are needed than those discussed above. Also, because there is a parting line and the pattern can be rernoved from the mold intact prior to closing and pouring, there are no dewaxina or burnout stages, and the casting specificati,ons are not as demand-20 ing. The sand mold is also normally at ambient temperaturewhen employed in casting. Generally, the strength of the sand mold is only a small fraction of the strength of the investment mold but is much more massive.
Casting molten metal into sand molds is a wiclely 25 used and accepted method of shaping parts. However, it does have several limitations inherent in the process.
Sand molds are made from sand, the qrains of which have a size of from about 30 to 100 per linear inch.
When these grains are compacted into a hard mass and held 30 together with a suitable binder the surface of the mold cavity (whlch is exposed -to the molten me-tal and aqalnst which this metal will solidify) will impart to the metal the same smoothness as the grains of sand of which it lS
composed. In terms of metal surfaces, this is not smooth.
Several things happen when the molten metal is poured into the sand mold cavity. At flrst, there is the dynamic charge of the fluid as lt pours into the void.
Then, there is a "quiet time" of the fluid as it rests against the sand walls and loses temperature, Finally, there is the act of solidification, wherein the fluid takes on the solid shape of the mold cavity, and ~ts 5 entire outside surface is in in-timate contact with the sand surface of -the mold cavity. This surface to surface contact is known as the metal/mold interface.
During the first dynamic stage when the mold cavity is being filled, the rushing fluid has a tendency 10 to pull off loose grains of sand from the mold surface and carry them along in the liqui~ metal. This causes inclusions in the metal as well as damage to the metal/
mold interface. If erosion is severe enough, the dimen-sions of the casting can be affected as well as the 15 integrity of the metal. Obviously, a sand mold surface with enough strength to withstand this erosive effect is required.
During the second static liquid stage when the fluid metal has filled the cavity and is now quietly 20 losing heat -through the metal/mold interface, the mold surface is being subjected to severe heat conditions. It must be remembered that prior to the molten me-tal enterinq the mold cavity, the sand surface was at amb-ient tempera-ture of perhaps 80 F. Now only a few seconds later, the 25 interface is at the molten metal temperature of perhaps 2800 F., with the thermal gradient being very steep and sweeping away fast from the metal. This is heat shock of the worst kind. The interface is thus subjected to high stresses, and in many cases the interface does not stand 30 up under such conditions. When failure of the mold surface at the interface occurs, it results in quite a few unique metal conditions. These are known by rather picturesque names: rat-tail, scab, penetration, vain, burn-in, orange-peel, nitrogen embrittlement, cill, cold shut, 35 porosity, and blow just to name a few. They a]l result jn added difficulties and expenses to the foundryman.
During the third solidifica-tion stage when the metal is becoming solid and taking on the shape and surface aspect of the mold cavity - now altered by erosion and heat-shock, the defects listed above are locked into the casting.
If improvemen-ts are to be made -in the cast~nq aspect relative to the weaknesses of the metal/mold interface, it is obvious from the above that these improve-ments must be made to the mold surface before the mold 1S
closed and the molten metal poured into the cavity. rhe 10 present invention provides such desirable interface characteristics.
The refractory composition in accordance with the invention formed from an admixture of the above discussed ingredients may be combined wi-th a refractory 15 powder, as has been previously mentioned, -to produce a slurry-like mixture for treating mold surfaces sometimes referred to as a wash. Preferably, the refractory powder is selec-ted from a group consisting of zircon, sillca, alumina-silicate, graphite, fused silica, alumnina, 20 chromite, fibrous-alumina silicate, magnesia, or combina-tion thereof. These refractory powders preferably are ground to a size smaller than about lO0 mesh.
The slurry produced can be applied to coat the sand mold surface of the cavity, e.g., by brush, spray, 25 dip, or swab methods. This coated surface is then allowed to dry with or without hea-t being applied, i.e., the refractory composition is gelled in place on the surface of the mold. The mold surface so coated has properties well suited to functioning as a metal/mold interface.
For example, the fine powdered refractories are much smaller than the voids between the sand grains on the surface of the mold. Therefore, the powdered refractories tend to deposit in -these voids as well as lay on the top surface of the uppermost sand grains. By so filling the 35 voids, a smooth surface resul-ts that is highly refractory and impervious to penetration by either the :Liquid metal or the metal vapors.
7~
Furthermore, with the present invention t'n s wash affects more than just the top surface of the mold.
If a cross section of the mold surface is examined under magnification, it can be seen that the fine powdered 5 refractory has penetrated to three or more sand grains down into the molding media. This means that the voids on the mold surface of the interface have been filled in ~J~ th a high quality refractory to a depth of three or more sand grains.
In addition, the liquid phase of the bi.nder composition of the invention penetrates and bonds the molcl sand mass from 1 lnch to several inches deep, depending upon the characteristics of the molding media. As a result of this deep mold i.nterface bonding, a hard mold surface lS results, which can withstand considerable thermal and mechanical shock.
~ y use of the lnventi.on in the form of a refractory composition coating on sand molds, the sand is bound -tightly together. Therefore, the sand will not erode 20 off the surface to become entrapped in the metal castlng as an inclusion. Further, because of -the hardness, there is less tendency for the surface of the mold to fracture, thus eliminating expansion defec-ts normally associated with a weak mold wall interface. As an added advarltage, 25 because the mold wall is smoo-th as a result of the refractory powder filling in the gaps between sand qrains, the solidification of the me-tal takes place agai.ns-t a smooth surface and results in a smoo-th metal casting.
In still another embodimen-t of the i.nvention, 30 the binder composition of the invention is used in a process known in the art as the V-process for preparlng sand molds for lar~e metal castin~s. As is no-ted above, the V-process is conventional in the art and basically comprises the steps of: providing a pattern for the 35 product to be produced; placing an organic plasti.c film over the pattern so that the plas-tic fil~ basically conforms to the shape of the pattern, e.g., via heatln(~
3 ~
the film to provide a good elasticity and pulliny a vacuum on the plastic through the mold pattern; coatin~ the exposed surface of the plastic film with a refractory wash; drying the refractory wash; placing a vacuum flas!~
5 so that it fits over and onto the plastic film and covers the pattern, the vacuum flask having a first opening suitable for receiving the pattern and a second openinq for the addition of sand to the flask; addinq sand to the flask through the second openin~ so that the sand is in 10 contact with the plastic film; vibrating the sand to compact and conform the sand to the shape of the pattern, closing the second opening so that at least a partial vacuum can be drawn on the sand in the flask; pullin~ at least a partial vacuum on the flask and the sand un-til the 15 sand is held in place against the refractory wash on the plastic film opposite the Pattern; releasin~ the pattern from the plastic film, e.g., by releasing the vacuum pulled on the plas-tic film through the pattern. This process provides a portion of a mold tha-t can be used 20 along with other similar molds in combination to provide large metal castings as are known in the art. The refractory washes which have been used in the past to coat the plastic have not provided an effective h:iah temperature vacuum seal in certain instances when the 25 metal for casting is placed in contact with the mold. For example, when a large mold is involved or when -the mold has sharp angles, etc., the heat of the molten metal vaporizes and/or decomposes the plastic film. Because the prior refractory washes employed did not provide an 30 effective vacuum barrier, -the vacuum seal created by the plastic was broken. Because the vacuum is now ~roken prlor to effective setting of solid metal, -the sand broke away and defects occurred in the casting.
It has now been found that the refractory 35 compositions of the present invention can be used in place of prior refractory washes to provide a superior metal/
mold interface as well as a good vacuum seal upon burninq away of the plastic film during the castinq step of th_ V-process. Thus, the refractory composition of the present invention main-tains a good vacuum in the sand ~nd prevents drop off of sand due to lack of vacuum at crucial areas.
5 Thus, the problems of surface finish and sand drop off are considerably alleviated with the presen-t invention. Thus, another embodiment of the invention provides a process comprising the steps of providing a pattern for the product to be produced; placing an organic plastic film 10 over the pattern so that the plastic film conforms to the shape of the pattern; coating the exposed surface of the plastic film with a binder and/or refractory composition comprising refractory partlcles and a binder composition, said binder composition being in accordance with the 15 invention as described above; and gelling said blnder and/or refractory composition. The remaininq steps of the V-process described above can also be performed as is conventional in thi.s art.
In still another embodiment, the refractory 20 composition of the present invention can also be used to make fired or non-fired refractory shapes.
In current practice, refractory shapes are generally manufactured by first mixing the refractory materials with water to form the shape des-ired. Some 25drying is then entailed to make the green ware readY for firing, which is the final s-tep. Although the in~redients are not too expensive, the firing can be very expenslve, especially in -the case of high -temperature refrac-tories.
As an alternative to firlng in the makina of 30 refractory shapes, several types of binder have been proposed and/or used that set at room temperatures, thereby eliminating the firing step in production. Some of the current materials used for this purpose are:
(l) Sodium Silicate: This has sodium 1ons ln its 35matrix and therefore will form low temperature liquid glass phase in the binder which severly restric-ts its application in high temperature work.
7v~
(2) Calcium Aluminate: Although an improvement o-n portland cement, which is a poor refractory cement, this binder is limited to about the 27000F. range depending on the manufacturer. The present invention will act as a 5 binder above 3100F, when desired.
(3) Various phosphates: These can be very useful in refractory work below 3000F. The present invention will act as a binder above 3100F.
(4) Ethyl Silicate: Although this binder has the 10 advantage of having only silicon dioxide as the refractory adhesive, it does a relatively poor job of bonding to the refractory aggregates. Therefore, shapes bonded with ethyl silicate tend to be weak.
(5) Colloidal Silica Sol: This binder forms its 15 strength by drying, and in large thick masses, it both takes a lonq time and shrinks. However, because the bond is pure silicon dioxide, the final bond is a good one for high temperature work.
These characteristics are provided by the binder and refractory compositions of the present lnvention. In particular, the refractory composi-tions of the present 10 invention can withstand temperatures of PCE 32-33 and have sufficient strength to also withstand the ~lost wax process" for preparing investment casting molds.
Investment casting molds are generally prepared by the "lost wax process". In this process, a wax mold is 15prepared in the shape desired for the ultimate metal casting. Binder is applied to this wax mold by dipping the mold into a refractory slurry such as a refractory composition of the invention. Filler particles such as refractory particles are then applied to the slurry 20coating on the wax mold and the binder com~osition is gelled. The wax mold is then again dipped into the refractory slurry, more filler particles applied, and the binder composition gelled again. These steps are repeated until the desired characteristics of -the refractory invest-25ment casting mold are achieved. Normally, -the size of the filler particles increases from the inside to -the outside of the casting mold.
The wax mold is then dewaxed by processes again conventional in the ar-t. The refractory slurry of the 30invention provides sufficient strength to -the mold to withstand the stresses during this dewaxing step.
The dewaxed investment mold prepared in accor-dance with the invention can be stored for long periods of time. It can then be used in a conventional investment 35casting process. During the casting process, the binder and refractory compositions must withs-tand even greater stresses.
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In preparing a fired investment mold, t'ne dewaxed investment mold is first fired to burn out temperatures of about 1800 F. This burn out accompllshes three things:
(1) it rids the mold cavi-ty of all residual organic matter;
(2) it oxidizes and recrystallizes all refractory materials to their most stable high temperature form; and (3) it heats the mold to decrease thermal shock from the molten metal during pour.
Thus, as is conventional in the art, due considera~lon must be given during formulation of the binder to compen-sate for the dimensional changes which take place within 15 the binder during the burnout period. Some mold failures are characterized by such things as frac-tures, warpage, passage restrictions, low strengths and perrneability problems. To some degree, these failures have been traced to refractory binders. 1`he present invention provides good 20 binder reliability.
In order to avoid the above problems, -the binder in the investment mold should withstand high temperature handling when the mold, which is normally at about 1800F., is moved from the burnout position~ which is 25 generally upside down, to the casting position, which is right side up. All of this requires ri~idi-ty under conditions which are prone towards plas-ticity because of glass formation.
The binder should also withstand the rigors of 30 the pour. This means that the mold cavity should be able to capture molten metal as it falls from the furnace or ladle and to withstand the two shocks encountered in such a fall. Thus, the binder should be able to withstand the mechanical shock of being hit with a falling mass having a 35 specific gravity of from 5 to 9 and the thermal shock of being hit with a very hot mass having a temperature difference of up to about 1000F or greater.
The binder should further decrepitate after ~,he metal solidifies so as not to place any undue mechanical stresses on the hot metal during its cooling stage, ,when it is shrinking and is prone to hot tears from the 5 stronger molding media.
The binder should not adhere to the metal surfaces after shake-out. If it does, the castina will have such defects as burn-ins, penetrations or other surfaces blemishes. In other words, it should break awa~
~o clean.
The binder and refractory compositions of the present ,invention provide these desirable results for investment casting molds.
In the case of sand mold casting, si,milar but 15 less stringent mold re~uirements are needed than those discussed above. Also, because there is a parting line and the pattern can be rernoved from the mold intact prior to closing and pouring, there are no dewaxina or burnout stages, and the casting specificati,ons are not as demand-20 ing. The sand mold is also normally at ambient temperaturewhen employed in casting. Generally, the strength of the sand mold is only a small fraction of the strength of the investment mold but is much more massive.
Casting molten metal into sand molds is a wiclely 25 used and accepted method of shaping parts. However, it does have several limitations inherent in the process.
Sand molds are made from sand, the qrains of which have a size of from about 30 to 100 per linear inch.
When these grains are compacted into a hard mass and held 30 together with a suitable binder the surface of the mold cavity (whlch is exposed -to the molten me-tal and aqalnst which this metal will solidify) will impart to the metal the same smoothness as the grains of sand of which it lS
composed. In terms of metal surfaces, this is not smooth.
Several things happen when the molten metal is poured into the sand mold cavity. At flrst, there is the dynamic charge of the fluid as lt pours into the void.
Then, there is a "quiet time" of the fluid as it rests against the sand walls and loses temperature, Finally, there is the act of solidification, wherein the fluid takes on the solid shape of the mold cavity, and ~ts 5 entire outside surface is in in-timate contact with the sand surface of -the mold cavity. This surface to surface contact is known as the metal/mold interface.
During the first dynamic stage when the mold cavity is being filled, the rushing fluid has a tendency 10 to pull off loose grains of sand from the mold surface and carry them along in the liqui~ metal. This causes inclusions in the metal as well as damage to the metal/
mold interface. If erosion is severe enough, the dimen-sions of the casting can be affected as well as the 15 integrity of the metal. Obviously, a sand mold surface with enough strength to withstand this erosive effect is required.
During the second static liquid stage when the fluid metal has filled the cavity and is now quietly 20 losing heat -through the metal/mold interface, the mold surface is being subjected to severe heat conditions. It must be remembered that prior to the molten me-tal enterinq the mold cavity, the sand surface was at amb-ient tempera-ture of perhaps 80 F. Now only a few seconds later, the 25 interface is at the molten metal temperature of perhaps 2800 F., with the thermal gradient being very steep and sweeping away fast from the metal. This is heat shock of the worst kind. The interface is thus subjected to high stresses, and in many cases the interface does not stand 30 up under such conditions. When failure of the mold surface at the interface occurs, it results in quite a few unique metal conditions. These are known by rather picturesque names: rat-tail, scab, penetration, vain, burn-in, orange-peel, nitrogen embrittlement, cill, cold shut, 35 porosity, and blow just to name a few. They a]l result jn added difficulties and expenses to the foundryman.
During the third solidifica-tion stage when the metal is becoming solid and taking on the shape and surface aspect of the mold cavity - now altered by erosion and heat-shock, the defects listed above are locked into the casting.
If improvemen-ts are to be made -in the cast~nq aspect relative to the weaknesses of the metal/mold interface, it is obvious from the above that these improve-ments must be made to the mold surface before the mold 1S
closed and the molten metal poured into the cavity. rhe 10 present invention provides such desirable interface characteristics.
The refractory composition in accordance with the invention formed from an admixture of the above discussed ingredients may be combined wi-th a refractory 15 powder, as has been previously mentioned, -to produce a slurry-like mixture for treating mold surfaces sometimes referred to as a wash. Preferably, the refractory powder is selec-ted from a group consisting of zircon, sillca, alumina-silicate, graphite, fused silica, alumnina, 20 chromite, fibrous-alumina silicate, magnesia, or combina-tion thereof. These refractory powders preferably are ground to a size smaller than about lO0 mesh.
The slurry produced can be applied to coat the sand mold surface of the cavity, e.g., by brush, spray, 25 dip, or swab methods. This coated surface is then allowed to dry with or without hea-t being applied, i.e., the refractory composition is gelled in place on the surface of the mold. The mold surface so coated has properties well suited to functioning as a metal/mold interface.
For example, the fine powdered refractories are much smaller than the voids between the sand grains on the surface of the mold. Therefore, the powdered refractories tend to deposit in -these voids as well as lay on the top surface of the uppermost sand grains. By so filling the 35 voids, a smooth surface resul-ts that is highly refractory and impervious to penetration by either the :Liquid metal or the metal vapors.
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Furthermore, with the present invention t'n s wash affects more than just the top surface of the mold.
If a cross section of the mold surface is examined under magnification, it can be seen that the fine powdered 5 refractory has penetrated to three or more sand grains down into the molding media. This means that the voids on the mold surface of the interface have been filled in ~J~ th a high quality refractory to a depth of three or more sand grains.
In addition, the liquid phase of the bi.nder composition of the invention penetrates and bonds the molcl sand mass from 1 lnch to several inches deep, depending upon the characteristics of the molding media. As a result of this deep mold i.nterface bonding, a hard mold surface lS results, which can withstand considerable thermal and mechanical shock.
~ y use of the lnventi.on in the form of a refractory composition coating on sand molds, the sand is bound -tightly together. Therefore, the sand will not erode 20 off the surface to become entrapped in the metal castlng as an inclusion. Further, because of -the hardness, there is less tendency for the surface of the mold to fracture, thus eliminating expansion defec-ts normally associated with a weak mold wall interface. As an added advarltage, 25 because the mold wall is smoo-th as a result of the refractory powder filling in the gaps between sand qrains, the solidification of the me-tal takes place agai.ns-t a smooth surface and results in a smoo-th metal casting.
In still another embodimen-t of the i.nvention, 30 the binder composition of the invention is used in a process known in the art as the V-process for preparlng sand molds for lar~e metal castin~s. As is no-ted above, the V-process is conventional in the art and basically comprises the steps of: providing a pattern for the 35 product to be produced; placing an organic plasti.c film over the pattern so that the plas-tic fil~ basically conforms to the shape of the pattern, e.g., via heatln(~
3 ~
the film to provide a good elasticity and pulliny a vacuum on the plastic through the mold pattern; coatin~ the exposed surface of the plastic film with a refractory wash; drying the refractory wash; placing a vacuum flas!~
5 so that it fits over and onto the plastic film and covers the pattern, the vacuum flask having a first opening suitable for receiving the pattern and a second openinq for the addition of sand to the flask; addinq sand to the flask through the second openin~ so that the sand is in 10 contact with the plastic film; vibrating the sand to compact and conform the sand to the shape of the pattern, closing the second opening so that at least a partial vacuum can be drawn on the sand in the flask; pullin~ at least a partial vacuum on the flask and the sand un-til the 15 sand is held in place against the refractory wash on the plastic film opposite the Pattern; releasin~ the pattern from the plastic film, e.g., by releasing the vacuum pulled on the plas-tic film through the pattern. This process provides a portion of a mold tha-t can be used 20 along with other similar molds in combination to provide large metal castings as are known in the art. The refractory washes which have been used in the past to coat the plastic have not provided an effective h:iah temperature vacuum seal in certain instances when the 25 metal for casting is placed in contact with the mold. For example, when a large mold is involved or when -the mold has sharp angles, etc., the heat of the molten metal vaporizes and/or decomposes the plastic film. Because the prior refractory washes employed did not provide an 30 effective vacuum barrier, -the vacuum seal created by the plastic was broken. Because the vacuum is now ~roken prlor to effective setting of solid metal, -the sand broke away and defects occurred in the casting.
It has now been found that the refractory 35 compositions of the present invention can be used in place of prior refractory washes to provide a superior metal/
mold interface as well as a good vacuum seal upon burninq away of the plastic film during the castinq step of th_ V-process. Thus, the refractory composition of the present invention main-tains a good vacuum in the sand ~nd prevents drop off of sand due to lack of vacuum at crucial areas.
5 Thus, the problems of surface finish and sand drop off are considerably alleviated with the presen-t invention. Thus, another embodiment of the invention provides a process comprising the steps of providing a pattern for the product to be produced; placing an organic plastic film 10 over the pattern so that the plastic film conforms to the shape of the pattern; coating the exposed surface of the plastic film with a binder and/or refractory composition comprising refractory partlcles and a binder composition, said binder composition being in accordance with the 15 invention as described above; and gelling said blnder and/or refractory composition. The remaininq steps of the V-process described above can also be performed as is conventional in thi.s art.
In still another embodiment, the refractory 20 composition of the present invention can also be used to make fired or non-fired refractory shapes.
In current practice, refractory shapes are generally manufactured by first mixing the refractory materials with water to form the shape des-ired. Some 25drying is then entailed to make the green ware readY for firing, which is the final s-tep. Although the in~redients are not too expensive, the firing can be very expenslve, especially in -the case of high -temperature refrac-tories.
As an alternative to firlng in the makina of 30 refractory shapes, several types of binder have been proposed and/or used that set at room temperatures, thereby eliminating the firing step in production. Some of the current materials used for this purpose are:
(l) Sodium Silicate: This has sodium 1ons ln its 35matrix and therefore will form low temperature liquid glass phase in the binder which severly restric-ts its application in high temperature work.
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(2) Calcium Aluminate: Although an improvement o-n portland cement, which is a poor refractory cement, this binder is limited to about the 27000F. range depending on the manufacturer. The present invention will act as a 5 binder above 3100F, when desired.
(3) Various phosphates: These can be very useful in refractory work below 3000F. The present invention will act as a binder above 3100F.
(4) Ethyl Silicate: Although this binder has the 10 advantage of having only silicon dioxide as the refractory adhesive, it does a relatively poor job of bonding to the refractory aggregates. Therefore, shapes bonded with ethyl silicate tend to be weak.
(5) Colloidal Silica Sol: This binder forms its 15 strength by drying, and in large thick masses, it both takes a lonq time and shrinks. However, because the bond is pure silicon dioxide, the final bond is a good one for high temperature work.
(6) Hybrid Colloidal Silica/Ethyl Silicate (e.g., 20 the hybrids disclosed in U.S. Patent Nos. 3,961,9~8 and 4,289,803 discussed above): Such a hybrid lacks the advantage of having an aprotic organic compound, as is present in the formulation of the invention, to provide wider variability in the binder composition and contents 25 as well as to add stability to the solution.
Non-fired refractory shapes are useful to the industrial community, because they make posslble fast equipment repairs, accurate pattern contact curing, lower cost field erection, automated in-plant fabrication, 30 energy savings, and a host of specialized saving and advantages inherent to each need. Therefore, the closer the non-fired refractory attributes come to the needs of the users, the more non-fired shapes there will be in use by industry. The compositions of the invention will 35 provide such useful characteristics.
In another application, the refractory composi-tions of the present inven-tion can be used to prepare non-fired refractory foams.
There has been a considerable amount of industrial demand for foam type materials, either materials foamed in place or bulk foamed. This foam 5 material can act as insulation, packing, filters, strainers, screens, decorations, structures, containers, etc. In other words, these foams have found a broad range of usefulness. In line with the above, it has been found useful to employ all manners of porous materials including 10 foams to strain liquids when temperatures do not exceed a few hundred degrees F. As the temperature goes up, however, this straining job becomes more difficult, until at the temperatures at which most commercial metals are liquid, there are very few materials available, if any, to 15 do the straining job. The present inven-tion provides a way to make a continuous refractory foam of any pore size desired and of any outside shape and dimension desired.
A refractory foam in accordance with the present invention can be made, for example, by forming a slurry 20 refractory composition in accordance with the invention using any refractory powder or combination of powders, such as zircon, silica, olivine, chromi-te, mullite, magnesium oxide, aluminum oxide, graphite, clay, etc.
Next, a piece o continuous porous organic foam is 25 provided having the pore size desired. The foam is cut and trimmed to the outside dimensions and shape desired in the finished refractory foam. The foam is dipped into the slurry so as to cover all the organic surfaces and drained so that the interior passage ways are not closed or 30 blocked. The piece is then gelled with a gelling agent or set aside to cure and harden, or baked at low temperatures to accelerate the cure. Once cured, the refractory foam is ready for use as a preferred high temperature metal strainer. For example, it can be placed in a stream of 35 metal to retain the entrained solids without burning away.
The following examples are presented to illustrate, but not to limlt, the compositions and processes of -the present invention.
A refractory binder in accordance with the present invention was prepared by utilizing the ingre-dients listed below:
_ GREDIENTS PARTS BY WEIGHT
Water (distilled, deionized) 1.8 Sulfuric Acid, Concentrated 0.12 Diethylene glycol monoethyl ether (DE) 52.16 Ethyl Silicate 40 8.0 Dimethyl methyl phosphonate (DMMP) 8.64 Colloidal Silica Sol 30.0 1 Remet Chemical Company.
Nalcoag 1129 from Nalco Chemical Company The water was placed into a water cooled reactor 15and the sulfuric acid was added. Then, the DE was added and agitation turned on. Next, the ethyl silicate is slowly added and the temperature monitored. The entire reaction is kept at between 20C. and 24C. During this part of the reaction, the ethyl silicate is hydrated. The 20DE is in the system to bring the oleophilic ethyl silicate into solution with the water. Only enough water is added to the system to hydrate the ethyl silicate. The reaction is exothermic, and therefore can be monitored. When the system stops giving off heat, the reaction is essentially 25complete. The agitator is then turned off and -the solution is allowed to sit for 72 hours so as to stabilize the hydrated ethyl silicate produced.
After 72 hours, the agitator is turned on again and the dimethyl methyl phosphonate is added. Mixing is 30performed for 1 minute. Then, over a period of time of about 6 minutes the colloidal silica sol was added. The resulting composition is mixed for several minutes and then stored.
This binder composition has been found to be 35stable against self-gellation for at least 6 months. The composition also gelled on command by addition of a gelling agent such as ammonium hydroxide to provide a single phase gel.
EXAMPLE 2:
A refractory binder composition in accordance with the present invention was prepared employing the following ingredients:
INGREDIENTSPARTS BY VOLUME
Sulfuric Acid, Concentrated0.33 ml Distilled Water 15.25 ml Diethylene glycol monoethyl ether 275.00 ml Ethyl Silicate 401 40.00 ml Colloidal Silica 2 151.5 ml DMMP 38.25 ml Remet Chemical Company 2 Nalcoag 1129 from Nalco Chemical Company These ingredients were mixed baslcally in 15 accordance with the procedure described in Example 1 above except that DMMP was added at the start with the DE. The resulting composition was found to he very stable against self-gellation even in view of the high ethyl silicate levels employed. The composition gelled on command with 20 ammonium hydroxide to provide a single phase gel.
EXAMPLE 3:
The procedure described in Example 1 above was repeated to prepare four additional binder compositions A, B, C and D employing the following ingredients-A B C D
DMMP 8.64 8.64 8.64 8.64 H20 2.48 3.38 4.05 4.73 30 DE 48.71 44.11 40.66 37.21 Nalcoag 1129 30 30 30 30 H2S04 .13 .14 .15 .16 All of the compositions A, B, C and D werestable against self-gellation and aelled on command by 35 addition o~ ammonium hydrox:ide to provide a single phase gel.
i lnterstab Zirco Drier Catalyst 24% was added t,o Composition A above and Zirconium Cem-All 24% was added ~o Composition B above. In each case, a small fall-out o~
solids occurred, probably because of a supersaturation, 5 ionic character or insolubility.
EXAMPLE 4:
A refrac-tory composition, e.g., for coating a mold can be prepared from the following ingredients:
INGREDIENTSPARTS BY WEIGHT
Zircon Flour 75 Polyvinyl Alcohol 0.5 Binder Compostiion from Example 1 24.5 Surfactant4 0.01 3 Vinol*available from Air Products Chemicals, Inc.
S505LF*Poly-tergent surfactant available from Olin Corporation The above ingredients are mixed in a reactor with an agitator and a water bath with the entire mix maintained at from 20 to 30C. at all times. 24.5 grams 20 of the refractory binder from Example 1 is placed into the reactor and 75 grams of a powdered zircon flour ground to 200 mesh is then mixed in. Mixing contlnues for 20 minutes, at which time 0.5 grams of polyvinyl alcohol and 0.1 grams of the surfactant are added. After a further 25 20 minu-tes of mixing, the mi~ing is stopped and the coating stored for use.
EXAMPLE 5:
A binder composition in accordance with the present invention was prepared from the following inqre-30 dients:
INGREDIENTS PA~TS BY WEIGllT
Ethyl Silicate 40 12 DMMP 2.5 Hydrochloric Acid (concentrated) 0.1 (40 drops !
35IPA (Isopropyl alcohol~ 51.9 Colloidal Silica Sol (Nalcoag 1129) 33.5 * trade marks ~ L_~
All the ingredients except the colloidal silicasol were placed in a reaction vessel equipped for agitation, and a glass funnel with a petcock was positioned above the reactor. The colloidal silica was splaced in the glass funnel. A thermometer was located permanently contacting the reactan-ts and readable from outside the reaction. The reactors were capable of being water cooled. With all apparatus in place, the colloidal silica was dripped into the reactor so as to give a 10 relative reaction time of from 1-2 hours. During the entire addition of colloidal silica sol, the reactor is kept in a constant state of agitation. The first stage of the reaction with the introduction of colloidal silica is the hydration of the ethyl silicate in the presence of the 15 mutual solvent. The water is provided by the collcidal silica sol. This hydration occurs over a period of about the first 25% of the reaction time. During the hydration period, exotherm occurs which is readily discernable through the optical thermometer. The termination of 20 hydration is indicated through the peaking of temperature.
After all of the colloidal silica sol is added, the resultant composition is capable of being used as a binder.
The resul-tant composition can be used as a binder material for investment casting molds, as a binder 25material for mold washes, as a parting agen-t for s-teel ingot stools and as a base for a corrosion resistant pain-t.
The resultant composition was mixed with zircon flour of 325 mesh size in a ratio of 1:3, respectively.
This refractory composition was applied as a coa-tinq to an 30 organic binder sand mold and was qelled or cured thereon by the application of heat. The resultant mold wash coating the core proved to be ceramic in quality, being very hard and deep penetrating and "rang" clearly like a bell.
EXAMPLE 6:
The procedure of Example 5 was repeated, exceDt that the following ingredients were employed and the water was dripped into the ethyl silicate, PM, DMMP and acid 5 prior to addition of the colloidal silica:
INGREDIENTS PARTS BY WEIGHT
Ethyl silicate 40 377 PM ~propylene glycol monomethyl ether) 479 10 Water (distilled) 60 H2S04 (concentrated) 1.5 (60 drops) Colloidal Silica Sol (Nalcoag 1129) 832 The resulting composition has been stable aga.inst self-gelling at ambient temperature for at least 2 15 months to this point.
EXAMPLE 7:
The procedure of Example 5 was repeated, except that the following ingredients were used and i-t took about 5 hours to add the colloidal silica sol:
20 INGREDIENTS PARTS BY WEIG~IT
Ethyl Silicate 40 20 PM 22.1 HCl (concentrated) 15 drops 25 Nalcoag 1034 47.9 The resulting composition was stable for 22 months. The composition was gelled to provide an investment casting shell into which was poured 316 Series stainless steel at 2975F. The shell did not crack and the 30 molten metal did not run out and provided an excellent quality casting.
EXAMPLE 8:
. . .
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
5 Ethyl Silicate 40 20 EE (ethylene glycol monoethyl ether) 37 Tributyl Borate 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 32.9 The above composition provided a binder com-position which has been stable against self-gelling at least 3 weeks to this point.
EXAMPLE 9:
The procedure of Example 5 was repeated, except 15 that the following ingredients were employed:
INGREDIENTSPARTS BY WEIGH r -Ethyl Silicate 40 20 Dimethylsulfoxide 10 PM (propylene monomethyl ether) 22 20 Hydrochloric Acid (concentrated) o,l (20 drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 The above composition provides a binder com-position which has been stable against self-gelling for at least 12 months to this point.
25 EXAMPLE 10:
The procedure of Example 5 was repea-ted, except that the following ingredients were employed:
INGREDIENTSPARTS BY WEIGHT
Ethyl Silicate 40 20 30 Dimethylformamide 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 The above composition provides a hi.nder com-35 position which was stable against self-gelling for at least one month.
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EXAMPLE 11:
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
sEthyl Silicate 40 20 Triethylphosphate 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 32.9 The above composition provides a binder com-position which has been stable against self-gelling for at least three weeks to this point.
EXAMPLE 12:
Basically -the same proce`dare as described in 15 Example 6 above was employed, except tha-t instead of dripping the colloidal silica sol into the reac-tor vessel via the glass funnel, small portions of colloidal si,lica sol were added by hand over a period of approximately 1 hours. The following ingredients were employed:
20 INGREDIENTS PARTS ~Y WEIGHT
Ethyl Silicate 40 20 DMMP ~
EE 22.1 Hydrochloric Acid (concentrated) 15 drops 25 Colloidal Silica Sol (Nalcoag 1034) 47.9 This composition was stable for at least three months and was used successfully to make investment casting shells. The relatively small amount of EE at 22.1%
reduced the stability significantly and the relatively 30 large amount of colloidal silica increased the water which also reduced stability.
COMPARATIVE EXAMPLE 13:
A binder composition employing phosphoric acid instead of DMMP and a relatively high ethyl silicate concentration was also prepared from the followina 5 ingredients:
INGREDIENTS VOLUME %
Phosphoric acid (85%) 5.00 ml Distilled Water 2.29 ml Ethyl Alcohol (95%) 37.90 ml lO Ethyl Silicate 40 43.91 ml Colloidal Silica Sol2 10.90 ml Remet Chemical Company Nalcoag 1129 from Nalco Chemical Company Half of the phosphoric acid and all of the 15 distilled water and ethyl alcohol were combined and the ethyl silicate was added thereto. The hydration of the ethyl silica-te was completed in about an hour. The colloidal silica was then added. After about 20 minutes, the second half of the acid was then added. After about 20 2-3 hours this solution gelled on its own.
COMPARATIVE EXAMPLE 14:
A binder composition including phosphoric acid and a relatively low concentration of ethyl silicate was prepared using the ingredients listed below. The water 25 acid and DE were placed in a reaction vessel. The ES-~O
was added slowly over a period of about 2 hours. Then, the colloidal silica sol was slowly mixed in over about 4 minutes:
INGREDIENTS VOLUME %
.
Phosphoric acid (85%) 25.0 ml Distilled Water 8.5 ml DE 275.0 ml Ethyl Silicate 401 40.0 ml Colloidal Silica Sol2151.51 ml Remet Chemical Company Nalcoag 1129 from Nalco Chemical Company The composition was found to be stable for at least nine months, but as noted above, it contained only 8 volume % ethyl silicate and therefore a low percentage of silica in the overall composition.
5 COMPARATIVE EXAMPLE 15:
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
Ethyl Silicate 40 20 10 TMP (trimethyl phosphite) 10 Hydrochloric Acid (concentrated) 0.1 ( drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 This composition had a three phase separation, 15 gelled in three days, and was not useful as a binder.
COMPARATIVE EXAMPLE 16:
Basically the same procedure as described in Example 5 above was employed, except that instead of dripping the colloidal silica sol into the rea~tor vessel 20small portions of colloidal silica sol were added by hand over a period of approximately 14 hours. The following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
Ethyl Silicate 40 20 25BAP (butyl acid phosphate) lO
Hydrochloric Acid (concentrated) 0.1 (30 dropsl Colloidal Silica Sol (Nalcoag 1034) 47.9 This material was milky in color, was opaque and 30had the appearance of gelled colloidal silica. Eventually, a separate solid phase se-ttled a-t the bottom.
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COMPARATIVE EXAMPLE 17:
200 ml of the composition of Exam~le 12 above was mixed with a solution of 2 grams of chromium acetyl-acetonate in 20 ml of propylene glycol monomethyl ether.
5Also, 200 ml of the composition of Example 12 above :ia_ separately mlxed with a solution of 2 ml of me-thylcyclo-pentadienyl manganese tricarbonyl in 20 ml of propylene glycol monomethyl ether. The compositions containinq the chromium or manganese compounds resulted in gels makina 10 the compositions unsuitable for use as binder compositions.
EXAMPLE 18:
The procedure of Example 5 above was repeated, with the following changes and ingredients:
INGREDIENTSPAF~TS BY WEIGHT
15 Ethyl Silicate 40 4.1 PM 36.3 DMMP 4.1 HC1 .1 Nyacol 2034 ~Colloidal 20 Silica with 34% SiO2 and 66% H20) 55.3 Klucel H (hydroxypropyl cellulose .1 The Klucel H was added wlth agitation to the 25 prepared binder composition after hydration of the Ethyl Silicate 40 was completed and all of the colloidal s~ ca had been added to the reactor. The propylene qlycol monoethyl ether was added in two parts. The initial amount of about 24.1 parts by weight was added ln preparinq the 30 binder compositions. The remaining 12.2 parts were added after the Klucel H was added to clean up some cloudiness that had developed upon addi-tion of the Klucel ~l.
The resultant binder composition (9.5 qrams) was mixed with zircon flour (24.5 grams) to provide a 35 refractcry composition. This refractory composition was "painted" in two coats onto the surface of a sand mold by flooding the area to assure penetration into the sand L r~
mass. The first coat was dried before application of the second coat. This wash provided an excellent surface for heavy steel casting. Moreover, application of the wash was quick and easy and the wash composition is relatively 5 economical because of the low ratio of the costly ingredients in the wash.
It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and 10 modifications without depar-ting from the spirit and scope of the invention. All such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Non-fired refractory shapes are useful to the industrial community, because they make posslble fast equipment repairs, accurate pattern contact curing, lower cost field erection, automated in-plant fabrication, 30 energy savings, and a host of specialized saving and advantages inherent to each need. Therefore, the closer the non-fired refractory attributes come to the needs of the users, the more non-fired shapes there will be in use by industry. The compositions of the invention will 35 provide such useful characteristics.
In another application, the refractory composi-tions of the present inven-tion can be used to prepare non-fired refractory foams.
There has been a considerable amount of industrial demand for foam type materials, either materials foamed in place or bulk foamed. This foam 5 material can act as insulation, packing, filters, strainers, screens, decorations, structures, containers, etc. In other words, these foams have found a broad range of usefulness. In line with the above, it has been found useful to employ all manners of porous materials including 10 foams to strain liquids when temperatures do not exceed a few hundred degrees F. As the temperature goes up, however, this straining job becomes more difficult, until at the temperatures at which most commercial metals are liquid, there are very few materials available, if any, to 15 do the straining job. The present inven-tion provides a way to make a continuous refractory foam of any pore size desired and of any outside shape and dimension desired.
A refractory foam in accordance with the present invention can be made, for example, by forming a slurry 20 refractory composition in accordance with the invention using any refractory powder or combination of powders, such as zircon, silica, olivine, chromi-te, mullite, magnesium oxide, aluminum oxide, graphite, clay, etc.
Next, a piece o continuous porous organic foam is 25 provided having the pore size desired. The foam is cut and trimmed to the outside dimensions and shape desired in the finished refractory foam. The foam is dipped into the slurry so as to cover all the organic surfaces and drained so that the interior passage ways are not closed or 30 blocked. The piece is then gelled with a gelling agent or set aside to cure and harden, or baked at low temperatures to accelerate the cure. Once cured, the refractory foam is ready for use as a preferred high temperature metal strainer. For example, it can be placed in a stream of 35 metal to retain the entrained solids without burning away.
The following examples are presented to illustrate, but not to limlt, the compositions and processes of -the present invention.
A refractory binder in accordance with the present invention was prepared by utilizing the ingre-dients listed below:
_ GREDIENTS PARTS BY WEIGHT
Water (distilled, deionized) 1.8 Sulfuric Acid, Concentrated 0.12 Diethylene glycol monoethyl ether (DE) 52.16 Ethyl Silicate 40 8.0 Dimethyl methyl phosphonate (DMMP) 8.64 Colloidal Silica Sol 30.0 1 Remet Chemical Company.
Nalcoag 1129 from Nalco Chemical Company The water was placed into a water cooled reactor 15and the sulfuric acid was added. Then, the DE was added and agitation turned on. Next, the ethyl silicate is slowly added and the temperature monitored. The entire reaction is kept at between 20C. and 24C. During this part of the reaction, the ethyl silicate is hydrated. The 20DE is in the system to bring the oleophilic ethyl silicate into solution with the water. Only enough water is added to the system to hydrate the ethyl silicate. The reaction is exothermic, and therefore can be monitored. When the system stops giving off heat, the reaction is essentially 25complete. The agitator is then turned off and -the solution is allowed to sit for 72 hours so as to stabilize the hydrated ethyl silicate produced.
After 72 hours, the agitator is turned on again and the dimethyl methyl phosphonate is added. Mixing is 30performed for 1 minute. Then, over a period of time of about 6 minutes the colloidal silica sol was added. The resulting composition is mixed for several minutes and then stored.
This binder composition has been found to be 35stable against self-gellation for at least 6 months. The composition also gelled on command by addition of a gelling agent such as ammonium hydroxide to provide a single phase gel.
EXAMPLE 2:
A refractory binder composition in accordance with the present invention was prepared employing the following ingredients:
INGREDIENTSPARTS BY VOLUME
Sulfuric Acid, Concentrated0.33 ml Distilled Water 15.25 ml Diethylene glycol monoethyl ether 275.00 ml Ethyl Silicate 401 40.00 ml Colloidal Silica 2 151.5 ml DMMP 38.25 ml Remet Chemical Company 2 Nalcoag 1129 from Nalco Chemical Company These ingredients were mixed baslcally in 15 accordance with the procedure described in Example 1 above except that DMMP was added at the start with the DE. The resulting composition was found to he very stable against self-gellation even in view of the high ethyl silicate levels employed. The composition gelled on command with 20 ammonium hydroxide to provide a single phase gel.
EXAMPLE 3:
The procedure described in Example 1 above was repeated to prepare four additional binder compositions A, B, C and D employing the following ingredients-A B C D
DMMP 8.64 8.64 8.64 8.64 H20 2.48 3.38 4.05 4.73 30 DE 48.71 44.11 40.66 37.21 Nalcoag 1129 30 30 30 30 H2S04 .13 .14 .15 .16 All of the compositions A, B, C and D werestable against self-gellation and aelled on command by 35 addition o~ ammonium hydrox:ide to provide a single phase gel.
i lnterstab Zirco Drier Catalyst 24% was added t,o Composition A above and Zirconium Cem-All 24% was added ~o Composition B above. In each case, a small fall-out o~
solids occurred, probably because of a supersaturation, 5 ionic character or insolubility.
EXAMPLE 4:
A refrac-tory composition, e.g., for coating a mold can be prepared from the following ingredients:
INGREDIENTSPARTS BY WEIGHT
Zircon Flour 75 Polyvinyl Alcohol 0.5 Binder Compostiion from Example 1 24.5 Surfactant4 0.01 3 Vinol*available from Air Products Chemicals, Inc.
S505LF*Poly-tergent surfactant available from Olin Corporation The above ingredients are mixed in a reactor with an agitator and a water bath with the entire mix maintained at from 20 to 30C. at all times. 24.5 grams 20 of the refractory binder from Example 1 is placed into the reactor and 75 grams of a powdered zircon flour ground to 200 mesh is then mixed in. Mixing contlnues for 20 minutes, at which time 0.5 grams of polyvinyl alcohol and 0.1 grams of the surfactant are added. After a further 25 20 minu-tes of mixing, the mi~ing is stopped and the coating stored for use.
EXAMPLE 5:
A binder composition in accordance with the present invention was prepared from the following inqre-30 dients:
INGREDIENTS PA~TS BY WEIGllT
Ethyl Silicate 40 12 DMMP 2.5 Hydrochloric Acid (concentrated) 0.1 (40 drops !
35IPA (Isopropyl alcohol~ 51.9 Colloidal Silica Sol (Nalcoag 1129) 33.5 * trade marks ~ L_~
All the ingredients except the colloidal silicasol were placed in a reaction vessel equipped for agitation, and a glass funnel with a petcock was positioned above the reactor. The colloidal silica was splaced in the glass funnel. A thermometer was located permanently contacting the reactan-ts and readable from outside the reaction. The reactors were capable of being water cooled. With all apparatus in place, the colloidal silica was dripped into the reactor so as to give a 10 relative reaction time of from 1-2 hours. During the entire addition of colloidal silica sol, the reactor is kept in a constant state of agitation. The first stage of the reaction with the introduction of colloidal silica is the hydration of the ethyl silicate in the presence of the 15 mutual solvent. The water is provided by the collcidal silica sol. This hydration occurs over a period of about the first 25% of the reaction time. During the hydration period, exotherm occurs which is readily discernable through the optical thermometer. The termination of 20 hydration is indicated through the peaking of temperature.
After all of the colloidal silica sol is added, the resultant composition is capable of being used as a binder.
The resul-tant composition can be used as a binder material for investment casting molds, as a binder 25material for mold washes, as a parting agen-t for s-teel ingot stools and as a base for a corrosion resistant pain-t.
The resultant composition was mixed with zircon flour of 325 mesh size in a ratio of 1:3, respectively.
This refractory composition was applied as a coa-tinq to an 30 organic binder sand mold and was qelled or cured thereon by the application of heat. The resultant mold wash coating the core proved to be ceramic in quality, being very hard and deep penetrating and "rang" clearly like a bell.
EXAMPLE 6:
The procedure of Example 5 was repeated, exceDt that the following ingredients were employed and the water was dripped into the ethyl silicate, PM, DMMP and acid 5 prior to addition of the colloidal silica:
INGREDIENTS PARTS BY WEIGHT
Ethyl silicate 40 377 PM ~propylene glycol monomethyl ether) 479 10 Water (distilled) 60 H2S04 (concentrated) 1.5 (60 drops) Colloidal Silica Sol (Nalcoag 1129) 832 The resulting composition has been stable aga.inst self-gelling at ambient temperature for at least 2 15 months to this point.
EXAMPLE 7:
The procedure of Example 5 was repeated, except that the following ingredients were used and i-t took about 5 hours to add the colloidal silica sol:
20 INGREDIENTS PARTS BY WEIG~IT
Ethyl Silicate 40 20 PM 22.1 HCl (concentrated) 15 drops 25 Nalcoag 1034 47.9 The resulting composition was stable for 22 months. The composition was gelled to provide an investment casting shell into which was poured 316 Series stainless steel at 2975F. The shell did not crack and the 30 molten metal did not run out and provided an excellent quality casting.
EXAMPLE 8:
. . .
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
5 Ethyl Silicate 40 20 EE (ethylene glycol monoethyl ether) 37 Tributyl Borate 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 32.9 The above composition provided a binder com-position which has been stable against self-gelling at least 3 weeks to this point.
EXAMPLE 9:
The procedure of Example 5 was repeated, except 15 that the following ingredients were employed:
INGREDIENTSPARTS BY WEIGH r -Ethyl Silicate 40 20 Dimethylsulfoxide 10 PM (propylene monomethyl ether) 22 20 Hydrochloric Acid (concentrated) o,l (20 drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 The above composition provides a binder com-position which has been stable against self-gelling for at least 12 months to this point.
25 EXAMPLE 10:
The procedure of Example 5 was repea-ted, except that the following ingredients were employed:
INGREDIENTSPARTS BY WEIGHT
Ethyl Silicate 40 20 30 Dimethylformamide 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 The above composition provides a hi.nder com-35 position which was stable against self-gelling for at least one month.
~ f~
EXAMPLE 11:
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
sEthyl Silicate 40 20 Triethylphosphate 10 Hydrochloric Acid (concentrated) 0.1 (20 drops) Colloidal Silica Sol (Nalcoag 1034) 32.9 The above composition provides a binder com-position which has been stable against self-gelling for at least three weeks to this point.
EXAMPLE 12:
Basically -the same proce`dare as described in 15 Example 6 above was employed, except tha-t instead of dripping the colloidal silica sol into the reac-tor vessel via the glass funnel, small portions of colloidal si,lica sol were added by hand over a period of approximately 1 hours. The following ingredients were employed:
20 INGREDIENTS PARTS ~Y WEIGHT
Ethyl Silicate 40 20 DMMP ~
EE 22.1 Hydrochloric Acid (concentrated) 15 drops 25 Colloidal Silica Sol (Nalcoag 1034) 47.9 This composition was stable for at least three months and was used successfully to make investment casting shells. The relatively small amount of EE at 22.1%
reduced the stability significantly and the relatively 30 large amount of colloidal silica increased the water which also reduced stability.
COMPARATIVE EXAMPLE 13:
A binder composition employing phosphoric acid instead of DMMP and a relatively high ethyl silicate concentration was also prepared from the followina 5 ingredients:
INGREDIENTS VOLUME %
Phosphoric acid (85%) 5.00 ml Distilled Water 2.29 ml Ethyl Alcohol (95%) 37.90 ml lO Ethyl Silicate 40 43.91 ml Colloidal Silica Sol2 10.90 ml Remet Chemical Company Nalcoag 1129 from Nalco Chemical Company Half of the phosphoric acid and all of the 15 distilled water and ethyl alcohol were combined and the ethyl silicate was added thereto. The hydration of the ethyl silica-te was completed in about an hour. The colloidal silica was then added. After about 20 minutes, the second half of the acid was then added. After about 20 2-3 hours this solution gelled on its own.
COMPARATIVE EXAMPLE 14:
A binder composition including phosphoric acid and a relatively low concentration of ethyl silicate was prepared using the ingredients listed below. The water 25 acid and DE were placed in a reaction vessel. The ES-~O
was added slowly over a period of about 2 hours. Then, the colloidal silica sol was slowly mixed in over about 4 minutes:
INGREDIENTS VOLUME %
.
Phosphoric acid (85%) 25.0 ml Distilled Water 8.5 ml DE 275.0 ml Ethyl Silicate 401 40.0 ml Colloidal Silica Sol2151.51 ml Remet Chemical Company Nalcoag 1129 from Nalco Chemical Company The composition was found to be stable for at least nine months, but as noted above, it contained only 8 volume % ethyl silicate and therefore a low percentage of silica in the overall composition.
5 COMPARATIVE EXAMPLE 15:
The procedure of Example 5 was repeated, except that the following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
Ethyl Silicate 40 20 10 TMP (trimethyl phosphite) 10 Hydrochloric Acid (concentrated) 0.1 ( drops) Colloidal Silica Sol (Nalcoag 1034) 47.9 This composition had a three phase separation, 15 gelled in three days, and was not useful as a binder.
COMPARATIVE EXAMPLE 16:
Basically the same procedure as described in Example 5 above was employed, except that instead of dripping the colloidal silica sol into the rea~tor vessel 20small portions of colloidal silica sol were added by hand over a period of approximately 14 hours. The following ingredients were employed:
INGREDIENTS PARTS BY WEIGHT
Ethyl Silicate 40 20 25BAP (butyl acid phosphate) lO
Hydrochloric Acid (concentrated) 0.1 (30 dropsl Colloidal Silica Sol (Nalcoag 1034) 47.9 This material was milky in color, was opaque and 30had the appearance of gelled colloidal silica. Eventually, a separate solid phase se-ttled a-t the bottom.
~2~7~
COMPARATIVE EXAMPLE 17:
200 ml of the composition of Exam~le 12 above was mixed with a solution of 2 grams of chromium acetyl-acetonate in 20 ml of propylene glycol monomethyl ether.
5Also, 200 ml of the composition of Example 12 above :ia_ separately mlxed with a solution of 2 ml of me-thylcyclo-pentadienyl manganese tricarbonyl in 20 ml of propylene glycol monomethyl ether. The compositions containinq the chromium or manganese compounds resulted in gels makina 10 the compositions unsuitable for use as binder compositions.
EXAMPLE 18:
The procedure of Example 5 above was repeated, with the following changes and ingredients:
INGREDIENTSPAF~TS BY WEIGHT
15 Ethyl Silicate 40 4.1 PM 36.3 DMMP 4.1 HC1 .1 Nyacol 2034 ~Colloidal 20 Silica with 34% SiO2 and 66% H20) 55.3 Klucel H (hydroxypropyl cellulose .1 The Klucel H was added wlth agitation to the 25 prepared binder composition after hydration of the Ethyl Silicate 40 was completed and all of the colloidal s~ ca had been added to the reactor. The propylene qlycol monoethyl ether was added in two parts. The initial amount of about 24.1 parts by weight was added ln preparinq the 30 binder compositions. The remaining 12.2 parts were added after the Klucel H was added to clean up some cloudiness that had developed upon addi-tion of the Klucel ~l.
The resultant binder composition (9.5 qrams) was mixed with zircon flour (24.5 grams) to provide a 35 refractcry composition. This refractory composition was "painted" in two coats onto the surface of a sand mold by flooding the area to assure penetration into the sand L r~
mass. The first coat was dried before application of the second coat. This wash provided an excellent surface for heavy steel casting. Moreover, application of the wash was quick and easy and the wash composition is relatively 5 economical because of the low ratio of the costly ingredients in the wash.
It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and 10 modifications without depar-ting from the spirit and scope of the invention. All such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (42)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A binder composition which is the result of combined ingredients comprising colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic organic compound which contains at least one element selected from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the binder composition against self-gelling, wherein said colloidal silica and said liquid material are present in a ratio by weight of from about 1:12 to about 75:1 respectively, said liquid material has at least 20% by weight SiO2, and said colloidal silica contains at least about 15% by weight of SiO2, and wherein said solvent and said organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase.
2. A binder composition according to Claim 1, wherein the ratio of said colloidal silica and said liquid material is from about 1:10 to about 10:1, respectively.
3. A binder composition according to Claim 1, comprising from about 1 to about 60% by weight of said liquid material containing Si-OH groups, from about 5 to about 75% by weight of said colloidal silica, from about to about 93.5% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
4. A binder composition according to Claim 1, comprising from about 2 to about 60% by weight of said liquid material containing Si-OH groups, from about 5 to about 55% by weight of said colloidal silica, from about 20 to about 50% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
5. A binder composition according to Claim 1, wherein said at least one organic compound contains phosphorus.
6. A binder composition according to Claim 1, wherein said at least one organic compound is selected from the group consisting of fully esterified alkyl or aryl phosphate esters, fully esterified alkyl or aryl pyro-phosphate esters, fully esterified alkyl or aryl phosphonate esters, fully esterified alkyl or aryl borate esters, fully esterified alkyl or aryl pyroborate esters, dialkyl or diaryl sulfoxides, N,N-dialkyl or -diaryl alkanamides, and mixtures thereof, wherein said alkyl groups contain from 1 to 6 carbon atoms and said aryl groups contain from 6 to 8 carbon atoms.
7. A binder composition according to Claim 1, wherein at least one organic compound is selected from the group consisting of dimethyl methyl phosphonate, triethyl phosphate, tributyl borate, dimethyl sulfoxide, dimethyl formamide and mixtures thereof.
8. A binder composition according to Claim 6, wherein said at least one organic compound comprises dimethyl methyl phosphonate.
9. A binder composition according to Claim 1, wherein said liquid material containing Si-OH groups comprises hydrated alkyl silicate.
10. A binder composition according to Claim 9, wherein said hydrated alkyl silicate is a hydrated ethyl silicate.
11. A binder composition according to Claim l, wherein said solvent is a water-miscible organic solvent.
12. A binder composition according to Claim l, comprising from about 2 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2;
from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 1 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 1 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
13. A binder composition according to Claim 1, comprising from about 5 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2;
from about 5 to about 40% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about .5 to about 12% by weight of dimethyl methyl phosphonate; and from about 20 to about 55% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
from about 5 to about 40% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about .5 to about 12% by weight of dimethyl methyl phosphonate; and from about 20 to about 55% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
14. A refractory composition comprising refractory particles and a binder composition, wherein said binder composition is the result of combined ingredients comprising colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the binder composition against self-gelling, wherein said colloidal silica and said liquid material are present in a ratio by weight from about 1:12 to about 75:1 respectively, said liquid material contains at least about 20% by weight SiO2, and said colloidal silica contains at least 15% by weight of SiO2, and wherein said solvent and said organic compound are present in amount sufficient to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase.
15. A refractory composition according to Claim 14, wherein the ratio of said colloidal silica and said liquid material is from about 1:10 to about 10:1, respectively.
16. A refractory composition according to Claim 14, comprising from about 1 to about 60% by weight of said liquid material containing Si-OH groups, from about 5 to about 75% by weight of said colloidal silica, from about 10 to about 93.5% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
17. A refractory composition according to Claim 14, wherein said binder composition comprises from about 2 to about 60% by weight of said liquid material containing Si-OH groups, from about 5 to about 55% by weight of said colloidal silica, from about 20 to about 50% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
18. A refractory composition according to Claim 14, wherein said refractory particles are selected from the group consisting of zircon, alumina, alumino-silicates, MgO, olivine, silica flour, fused quartz, graphite and mixtures thereof.
19. A refractory composition according to Claim 14, wherein said at least one organic compound contains phosphorus.
20. A refractory composition according to Claim 14, wherein said at least one organic compound comprises dimethyl methyl phosphonate.
21. A refractory composition according to Claim 14, wherein said liquid material containing Si-OH
groups is a hydrated ethyl silicate.
groups is a hydrated ethyl silicate.
22. A refractory composition according to Claim 14, comprising from about 2 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2; from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 5 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
23. A refractory composition according to Claim 14, wherein said binder composition comprises from about 5 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight SiO2; from about 5 to about 40%
by weight acidic colloidal silica containing from about 15 to about 60% by weight SiO2; from about .5 to about 12% by weight of dimethyl methyl phosphonate; and from about 20 to about 55% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
by weight acidic colloidal silica containing from about 15 to about 60% by weight SiO2; from about .5 to about 12% by weight of dimethyl methyl phosphonate; and from about 20 to about 55% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
24. A method for making a mold for investment casting, said method comprising the steps of (1) forming a wax mold in a predetermined shape; (2) applying to said wax mold a refractory slurry comprising filler particles and a binder composition, wherein said binder composition is the result of combined ingredients comprising colloidal silica, liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic organic compound which contains at least one element from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the binder composition against self-gelling; wherein said colloidal silica and said liquid material are present in a ratio by weight from about 1:12 to about 75:1 respectively, said liquid material contains at least about 20% by weight SiO2, and said colloidal silica contains at least about 15% by weight of SiO2; and wherein said solvent and said organic compound are present in amounts sufficient to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder which gels to a single phase; and (3) gelling the binder composition so that the refractory slurry forms a casting mold conforming to the shape of the wax mold.
25. A method according to Claim 24, wherein said applying step is performed by (1) applying refractory slurry to the wax mold by dipping the wax mold into the refractory slurry to provide a wax mold having a coating of the slurry thereon, (2) applying filler particles to the coating of binder on the wax mold, (3) gelling the refractory slurry to bond the applied filler particles, and (4) repeating steps (1), (2) and (3) until a mold of the desired refractory characteristics is obtained.
26. A method according to Claim 25, wherein the mold is dewaxed.
27. A method according to Claim 24, wherein the binder composition comprises from about 1 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2; from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 1 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
28. A method for coating a refractory mold comprising the steps of (1) mixing refractory particles with a binder composition to provide a coating composi-tion, wherein said binder composition is the result of combined ingredients comprising colloidal silica, liquid material containing Si-OH groups, a solvent capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic organic compound which contains at least one element from the group consisting of phosphorus, sulfur, boron, nitrogen and mixtures thereof and which stabilizes the binder composition against self-gelling; wherein said colloidal silica and said liquid material are present in a ratio by weight from about 1:12 to about 75:1 respectively, said liquid material contains at least about 20% by weight of SiO2, and said colloidal silica contains at least about 15% by weight of SiO2; and wherein said solvent and organic compound are present in amounts sufficient to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase; (2) applying the coating composition to a refractory mold surface; and (3) gelling the coating composition on the surface of the refractory mold.
29. A method according to Claim 28, wherein the binder composition comprises from about 5 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2; from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 5 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
30. The process for providing a refractory, vapor barrier surface for a vacuum mold interior for a metal casting mold, said process comprising the steps of providing a pattern for the product to be produced;
placing an organic plastic film over the pattern so that the plastic film conforms to the shape of the pattern;
coating the exposed surface of the plastic film with a binder composition which is a result of combined ingre-dients comprising colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the binder composition against self-gelling, wherein said colloidal silica and said liquid material are present in a ratio by weight of from about 1:12 to about 75:1 respectively, wherein said liquid material has at least 20% by weight SiO2 and said colloidal silica contains at least about 15% by weight of SiO2, and wherein said solvent and said organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase;
and gelling said binder composition.
placing an organic plastic film over the pattern so that the plastic film conforms to the shape of the pattern;
coating the exposed surface of the plastic film with a binder composition which is a result of combined ingre-dients comprising colloidal silica, a liquid material containing Si-OH groups, a solvent which is capable of solubilizing the liquid material and the colloidal silica, and at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the binder composition against self-gelling, wherein said colloidal silica and said liquid material are present in a ratio by weight of from about 1:12 to about 75:1 respectively, wherein said liquid material has at least 20% by weight SiO2 and said colloidal silica contains at least about 15% by weight of SiO2, and wherein said solvent and said organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase;
and gelling said binder composition.
31. A process according to Claim 30, wherein the binder composition coated on the plastic film further comprises refractory particles.
32. A process according to Claim 30, further comprising the steps of placing a vacuum flask over and on the plastic film and the gelled binder coating so that the flask fits over the pattern, said vacuum flask having a first opening suitable for receiving at least the surface of the plastic film having the binder composition coated thereon and having a second opening for addition of sand to the flask; adding sand to the flask through the second opening so that the sand is in contact with the binder coating on the plastic film; vibrating the sand to compact and conform the sand to the shape of the pattern; closing the second opening so that at least a partial vacuum can be drawn on the sand in the flask; pulling at least a partial vacuum on the flask and the sand therein so that the sand is held in place in contact with the binder coating and conforms to the shape of the pattern; and releasing the plastic film from the pattern to provide at least a portion of the metal casting mold.
33. A process according to Claim 30, wherein the binder composition comprises from about 2 to about 40% by weight of ethyl silicate that has been hydrated, said ethyl silicate containing from about 28% to about 60% by weight of SiO2; from about 5 to about 60% by weight acidic colloidal silica containing from about 15 to about 60% by weight of SiO2; from about 1 to about 20% by weight of dimethyl methyl phosphonate; and from about 20 to about 60% by weight of a solvent selected from diethylene glycol monoethyl ether, propylene glycol monomethyl ether, or propylene glycol monopropyl ether.
34. A process for preparing a binder composition comprising the steps of providing a reaction mixture comprising acid, a silicate ester which is capable of being hydrolyzed to liquid materials containing Si-OH
groups, and a solvent which solubilizes the silicate ester and which also will solubilize colloidal silica sol; and adding an aqueous based colloidal silica sol to the reaction mixture at a rate sufficient to hydrate the silicate ester without gelling the resulting binder composition, wherein the water present in the colloidal silica sol provides substantially all of the water to hydrate the silicate ester and wherein the acid is present in an amount sufficient to catalyze the hydration reaction and to provide a final pH of from about 1 to about 3 for the resulting binder composition; and adding to the reaction mixture at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the resulting binder composition against self-gelling.
groups, and a solvent which solubilizes the silicate ester and which also will solubilize colloidal silica sol; and adding an aqueous based colloidal silica sol to the reaction mixture at a rate sufficient to hydrate the silicate ester without gelling the resulting binder composition, wherein the water present in the colloidal silica sol provides substantially all of the water to hydrate the silicate ester and wherein the acid is present in an amount sufficient to catalyze the hydration reaction and to provide a final pH of from about 1 to about 3 for the resulting binder composition; and adding to the reaction mixture at least one aprotic, non-ionic, non-metallic, organic compound which contains at least one element selected from the group consisting of phosphorus, sulfur, boron, nitrogen, and mixtures thereof and which stabilizes the resulting binder composition against self-gelling.
35. A process according to Claim 34, wherein the organic compound is added to the reaction mixture prior to addition of the colloidal silica sol.
36. A process according to Claim 34, wherein forming the reaction mixture the acid is added to a mixture comprising the silicate ester ester and the solvent.
37. A process according to Claim 34, wherein said colloidal silica is added to the mixture in an amount to provide a ratio by weight of said colloidal silica to said liquid material of from about 1:12 to about 75:1, said liquid material has at least 20% by weight SiO2, and said colloidal silica contains at least about 15% by weight of SiO2, and wherein said solvent and said organic compound are present in amounts so as to solubilize the liquid material and the colloidal silica, to provide a binder composition which is stable against self-gellation, and to provide a binder composition which gels to a single phase.
38. A process according to Claim 37, wherein the binder composition comprises from about 1 to about 60% by weight of said liquid material containing Si-OH groups, from about 5 to about 75% by weight of said colloidal silica, from about 10 to about 93.5% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
39. A process according to Claim 37, wherein the resulting composition comprises from about 2 to about 60%
by weight of said liquid material containing Si-OH groups, from about 5 to about 55% by weight of said colloidal silica, from about 20 to about 50% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
by weight of said liquid material containing Si-OH groups, from about 5 to about 55% by weight of said colloidal silica, from about 20 to about 50% by weight of said solvent, and from about .5 to about 50% by weight of said organic compound.
40. A process according to Claim 37, wherein said at least one organic compound contains phosphorus.
41. A process according to Claim 37, wherein the silicate ester is an alkyl silicate, the solvent is selected from the group consisting of diethylene glycol monoethyl ether and propylene glycol monomethyl ether, and the organic compound is dimethyl methyl phosphonate.
42. A process according to Claim 35, wherein the temperature during the addition of the colloidal silica sol is maintained from about 15 to about 31°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000449376A CA1216704A (en) | 1984-03-12 | 1984-03-12 | Binder and refractory compositions and methods |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000449376A CA1216704A (en) | 1984-03-12 | 1984-03-12 | Binder and refractory compositions and methods |
| FR8404528A FR2561553B1 (en) | 1984-03-23 | 1984-03-23 | REFRACTORY BINDER COMPOSITION AND PROCESS FOR PRODUCING THE SAME |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1216704A true CA1216704A (en) | 1987-01-20 |
Family
ID=25670320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000449376A Expired CA1216704A (en) | 1984-03-12 | 1984-03-12 | Binder and refractory compositions and methods |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1216704A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8003579B2 (en) | 2006-04-24 | 2011-08-23 | Epg (Engineered Nanoproducts Germany) Ag | Oil-, hot water-and heat-resistant binders, process for preparing them and their use |
| EP3301079A1 (en) * | 2016-09-29 | 2018-04-04 | Refractory Intellectual Property GmbH & Co. KG | Refractory ceramic batch and method for producing a refractory ceramic product |
-
1984
- 1984-03-12 CA CA000449376A patent/CA1216704A/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8003579B2 (en) | 2006-04-24 | 2011-08-23 | Epg (Engineered Nanoproducts Germany) Ag | Oil-, hot water-and heat-resistant binders, process for preparing them and their use |
| EP3301079A1 (en) * | 2016-09-29 | 2018-04-04 | Refractory Intellectual Property GmbH & Co. KG | Refractory ceramic batch and method for producing a refractory ceramic product |
| WO2018059812A1 (en) * | 2016-09-29 | 2018-04-05 | Refractory Intellectual Property Gmbh & Co. Kg | Refractory ceramic batch and method for producing a refractory ceramic product |
| EP3461802A1 (en) * | 2016-09-29 | 2019-04-03 | Refractory Intellectual Property GmbH & Co. KG | Refractory ceramic batch and method for producing a refractory ceramic product |
| CN109641801A (en) * | 2016-09-29 | 2019-04-16 | 里弗雷克特里知识产权两合公司 | Refractory ingredient and the method for preparing refractory ceramic product |
| RU2749520C2 (en) * | 2016-09-29 | 2021-06-11 | Рифрэктори Интеллектчуал Проперти Гмбх Унд Ко. Кг | Refractory ceramic mixture, as well as a method for obtaining ceramic refractory |
| US11377391B2 (en) | 2016-09-29 | 2022-07-05 | Refractory Intellectual Property Gmbh & Co. Kg | Refractory ceramic batch and method for producing a refractory ceramic product |
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