CA1315926C - Process for the manufacture of carbon-bound shaped parts which contain mineral fibres - Google Patents
Process for the manufacture of carbon-bound shaped parts which contain mineral fibresInfo
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- CA1315926C CA1315926C CA000567094A CA567094A CA1315926C CA 1315926 C CA1315926 C CA 1315926C CA 000567094 A CA000567094 A CA 000567094A CA 567094 A CA567094 A CA 567094A CA 1315926 C CA1315926 C CA 1315926C
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B30/00—Compositions for artificial stone, not containing binders
- C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/013—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics containing carbon
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
- C04B35/80—Fibres, filaments, whiskers, platelets, or the like
- C04B35/82—Asbestos; Glass; Fused silica
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Civil Engineering (AREA)
- Ceramic Products (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Mold Materials And Core Materials (AREA)
Abstract
A B S T R A C T
PROCESS FOR THE MANUFACTURE OF CARBON-BOUND SHAPED PARTS WHICH CONTAIN
MINERAL FIBRES
Shaped parts which contain refractory or fireproof mineral fibres, are manufactured by a process in which the mineral fibres are embedded in a carbonaceous matrix. The shaped parts are carbon-bound and contain mineral fibres. Finely particled pitch, tar or resol or novolak resins from an aqueous suspension is flocculated onto the mineral fibres which are present in the aqueous suspension. Then a green shaped part is produced from the suspension and this green shaped part is dried and subjected to pyrolysis at temperatures of from 350°C to 1300°C. The bulk density of the shaped parts can be adjusted over a wide range.
Very low bulk densities can be achieved.
PROCESS FOR THE MANUFACTURE OF CARBON-BOUND SHAPED PARTS WHICH CONTAIN
MINERAL FIBRES
Shaped parts which contain refractory or fireproof mineral fibres, are manufactured by a process in which the mineral fibres are embedded in a carbonaceous matrix. The shaped parts are carbon-bound and contain mineral fibres. Finely particled pitch, tar or resol or novolak resins from an aqueous suspension is flocculated onto the mineral fibres which are present in the aqueous suspension. Then a green shaped part is produced from the suspension and this green shaped part is dried and subjected to pyrolysis at temperatures of from 350°C to 1300°C. The bulk density of the shaped parts can be adjusted over a wide range.
Very low bulk densities can be achieved.
Description
131~2~
This invention relates to a process for the m~lufacture of carbon-bound shayed parts which contain mineral fibres.
The invention concerns a process for the manufacture of shaped parts which contain r~fractory or fireproof mineral fibres, in which process the mineral fibres are embeddea in ~ carbonaceous matrjx. The invention also conce ms sllaped parts which are carbon-bound and which contain mineral fibres m~lufactured accordin~ to this process.
Carbon-bo~l~ shaped parts containing mineral ibres are kno~. Thus, a moulde~ body composed of a heat-insulating material and a process for its manufacture are described in DE 30 09 182 C2. According to this m~lufacturillg process, carbonaceous substances, e.g. solid resins, either are mixed with the mineral fibres which form 15 to 60% by mass of the material of the moulded bod~, or the fibres are immersed in liqui~
carbonaceous substances. Synthetic resins, bituminous mineral oil or tar may be used as the carbonaceous substances. The pyrolysis, or cracking, of the carbonaceous substances tllen take place after shaping.
In addition, a refractory, heat-insulating material which is composed of aluminium silicate fibres and a binding agent, and which con~ains particulate, refractory fillers, is know~l from DE-~S 19 47 904. A
furtller plate material whlch contains ceramic fibres, and a process for its productioll~ are described in EP 00 77 444 Al. The manufacture of this~ plate material also takes ~lace from an aqueous slurry of the flbres. Such a slurry contains inorganic, refractory fillers. A
flocculation agent or a precipitation agent is used in the form of a cationic polyacryl ~nide. A process for the manufacture of light-weigll ', .: , ~, " ,,, ~ , . . .
. --3--13~926 shaped bodies composed of ceramic fibres, finely divided refractory matter, inorganic binding a~ents and conventional additives, is known from ~ 34 36 781, wherein, a two-stage flocculent-precipitation yrocess and a mixing of the two ~locculated dispersions takes place. Accordillg to thi.s state of the art, using a di.spersion of the fibres for shaping, with or without 1Occulatioll, however, no shaped bodies which have a carbon bond are manufactured.
;
The present illvention provides a process for the manufacture of shaped parts ~hich contain refractory or fireproo~ milleral ~ibres, in w}lich process the mineral fibres are embedded in a carbonaceous matrix, wherein finely particled pitch, tar or resol or novolak resins are flocculated from an aqueous suspension onto the mineral fibres present in the aqueous suspension, a green shaped part is produced from the suspension, and the green shaped part is dried and subjected to pyrolysis at temperatures of from 350~C to 1300~C. The parts produced have a carbon bond and carbonaceous phase. The process is simple in its execution and facilitates the manufacture of such shaped parts, ~he bulk density of whi.ch can be widely adjusted. In particular a low bulk densi.ty can be ac!lieved.
;
Accolding to a preferred embodiment, finely particled refractory or fireproof substances and/or inorganic binding agents and~or hydraulically setting refractory cements are also flocculated onto the minelal fibres in the suspension.
, .. .
.
13~26 As a result hereof, it is possible to re~ulate the properties of the resulting refractory shaped parts and, also, to control their bulk density. ~loreover, the advantage arises, when usin~ inor~anic binding agents, that a relatively great strength can be achieved in ~l intermediate temperature range of 40U to 800C and, when using hydraulically setting refractory cements. A further advanta~D is that, after drying, a high green stren~t}l of the shaped body is already achieve~.
Jn a furtller preferred elllbodim~nt, a cationic s~arch is used as flocculation agent.
In the process according to the invention, the mineral fibres may be added in a quantity of from 5 to 90% by mass, the pitch, the tar or the resol or novolak resin in a quantity of from 10 to 30, preferably 15 to 25~ by mass, the finely particled refractory or fireproof substances in a quantity of from 5 to 70~ by mass, the inorganic bindi.ng agents in a quantity of from 5 to Z5% by nlass, and the hydraulically setting refractory cements in a quantity of Erom S to 20% by mass, these speclfications relating to the dried shaped part which has not yet been subjected to pyrolysis.
lhe refrnctory or f~reproof mlneral fibres used in the process according to ~he invention can be any milleral fibres, preferably fibres of silicon dioxi.de, of aluminium oxide, the A12O3 con~ent of which is preferably at least 72%, or of an alumi.nium silicate material, in parti.cular having at least 40 to 60% of Al~03 and 6U to 40% of SiO2.
~.;
::, ~' , .. ~ . ...
131~92~
i`he diameter of these mineral fibres is preferably smaller than 15 l~n, i.e. so small that breaking of the fibres when tlley are processed need not be feared. Jn view o the conditions under which such fibres are produce~, their di~neter is usually greater than 1 ~m.
Tlle length of these fibres conveniently should exceed 3 mm, so that the fibres can fulfill their funstion as mechanical reinforcillg Wit}lill the shaped body. lhere is no critical maxim~n value for the length of the fibres, with the exception of the critical len~th determjned by the m~mler of manufacture of tlle fibres.
In the process according to the invelltion, a finely particled pitch, tar or resol or novolak resin is used. These are con~nercially known substances. The maxim~n grain size o these ~inely particled carbonaceous substances is, preferably, 0,09 nnn The finely particled curbonaceous substances cause the developmei~t of the strength of the shaped parts durin~ drying at temperatures exceeding 30C. The fi3lely particled carbonaceous substances in addition fonn a carbonaceous phase, i.e. accwnulations and coatings fo~n Oll the mineral fibres and, in the case of a large component of carbonaceous substances, a continuous carbonaceous matrix is achieved. Ater pyrolysis by heat treatmellt of the shaped part, the carbonaceous phase results in the improved resistance to abrasion and resistance to corrosion.
~; Flocculatioll agents are used in the process. These are anionic or cationlc substances, cationic starcbes being preferTed. The cationic polyacrylamide flocculation agellls used in ~P 00 77 4~ can, however, ~, , .. . ~ ,., . ~ . .
also be elllployed, as can other cationic flocculatioll agents, kno~m yer se, in the form of polyelectrolytes, e.g. methacrylate. These cationic flocculatjon agents are usually prepared in the fonn of a solution having a concelltratioll of 0,5 to 1% by mass, and are further diluted before use to solutions of OJOS to 0,1% by mass; a similar situation arises in respect of aniol]ic agents, such as anionic polyeletrolytes based on acrylic amide.
According to a further preferred embodimeJlt, finely particled, refractory or fireproof substances are flocculated OlltO the mineral fibres in the aqueous suspension, together with the pitch, tar or resol or novolak resin. Such finely particled or finely divided refractory matter having a grain size of~ 0,09 nm can be convelltional refractory matter, e.g. fireclay, bauxite, alumina, carundum, zirconiu~ dioxide, zircon mineral, magnesium oxide, cordierite, carbon, i.e. graphite, coke, silicon carbide and/or chrolni~ oxide. Such finely particled refractoly matter can be used si~lgly or in the form of mixtures.
In addition, in the process according to the invention, an inorganic bindiJlg a~ell-t can also be flocculated together Wit]l the pitCll, tar or resol or novolak resin. Such inorganic binding agents may be colloi~al SiOz or colloidal A12O3. The strength of the shaped parts is further improved by means of these inorganic binding agellts.
Ill the same way, hydraulically setting refractory cemen~s, e.g.
alwninous cement or rapid-hardening cements having a high A12O3 conten~
can be flocculated together with the pitch, tar or resol or novolak . ,~ ., .,, ~.. . . .. . .
131~92~
resin. The shaped part obtains its strength as a result of the setting of the refractory cemeIlt. The finely particled refractory matter, iIlorganic binding agents and hydraulically setting refractory cemeIlts can, in each case, be used individually or in any desired mixture or combination.
In the process according to the invention, mineral fibres in the suspension are pre$erably used in a cluwltity of from 5 to 15~ by mass or 6~ to 70% by mass. Shaped parts having a low mineral-fibre component are distinguished by a relatively low speci~ic gravity an~ a low theImal conductlvity, while manifesting good strength ~Id resistance to wear.
In the case of a lar~er mineral-fibre component, there is, at ~irst, only~a slight reduction in the specific gravity. At the same tin~e, the strength is gre~tly reduced, with the result that such compositioIls of the suspensioIl should not be regarded as be~ng particularly suitable.
It is only when there is a predomin~lt co~nponent of mineral fibr~s from about 6~% by mass, that shape~ parts are obtained in advantageous manner which have a very low thennal conductivity, low specific gravity and relatively high strength.
.
In order to protect the carbon~ceous phase in the shaped parts against .
corrosion by way of oxidation, elementary silicon or metallic aluminium in the folm of a powder having a grain size below 0,09 nm can be illtroduced into the susyension as antioxida~lt agents during the mallufacture of the shaped paTts~ In the~course ~f the pyrolysis of the shaped~parts by means of heat treatment, the ~ltioxidant agent partially .
~ ;; reacts~wlth the carbon to form carbides.
; ~
::
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,~.,,,~- : ~ ... .
. ~ , 13~926 In the process according to the invention, as a first step, an aqueous suspension of the mineral fibres is prepared. Such a suspension usually has u consistellcy of 0,5 to 3% by mass. Subsequent to the preparation of this a~lueous suspension of the milleral fibres, the finely par~icled pitch, tar or resol or novolak resin is scattered into this suspension and mi~ed well therewith. In like manner, finely particled refractory matter, inor~anic binding agents and hydraulically setting refractory cemellts are, optionally, added In this stage. Subse~uently, the solution of tlle flocculation agent described above is added, usually in a qu~tity of 5 g o~ the flocculation agent, calculated as solid matter, per 100 kg of the suspension.
Subsequently, the green shaped body is moulded from the dispersion which colltaills the flocculated suspension, in the usual manner. The dispersion is fillecl into a mould which has a perforated bottom. The dispersioll is dewatered by means of the draining of the liquid through the perforated bottom, this process possibly being assisted by establishing a vacuwn, and possibly by additional pressing power, ancl the shaped body is formed.
Ihe shaped bodies are usually dried at temperatures of from 110 to 180C. After dryin~, the shaped parts are treated at temperatures of between 350C up to temperatures of~ 1300C. A partial or com~lete pyrolys~s, or cokin~, of the pitch, tar or resol or novolak resins, takes place. This results in the fonnation or intensification of tlle carbon-binding of t}le mineral fibres and the furtller development of the carbonaceous phase. In the case of a high component of the carbonaceous ::
. ,~ .. .
9 ~ ~ -yhase, the milleral fibres can be en~.bedded in it, as in a carbonaceous matri~. The temperature of the heat treatnlent in each case depends on the finely particled pitch, tar or resol or novolak resin used, and furthemlore whether a shayed part is required which has already been subjected to pyrolysis up to 10~%, or whether a subsequent pyrolysis of the shaped part is possible or desired when in use by the end-user.
The heat treatment for the pyrolysis, or coking, of the pitch, tar, resol or novolak resin is undertakell in the maluler kno~l per se in llOII-OXi.diZillg a~mosphere, i.e. in an inert gas, such as nitrogen, car~on monoxide or carbon dioxide.
The invention will be described in more detail with reference to the ollowing non-limitin~ E~amples.
~xan~le ]
63 parts by mass of mineral fibres having an A1203 content of 47% by mass, remainder SiO2, were reduced to a 1% suspension with water with the assist~lce of a powerful stirring apparatus. To this were added 7,5 parts by mass colloidal sllica, 23 yarts by mass of a finely particled solid novolak resin having an average grain size of 2 to 3 ~, and 6,5 parts by mass o~ finely particled alumina~(A1~03~ having a grain size of ~10 ~m, and were also well stirred in the suspensioll. Subsequently, a 0,5% solution of a cationic starch was added, causing the flocculation of the novolak resin arid the finely particled refractory matter and of the inorganic binding agent. The solution was dewatered on a screen , ~31~
mould with the creation of a vacuum to fonn plates, and these plates were subsequently dried at lZ0 to 150C. These plates were then heat-treate~ in a non-oxi~izi-l~ atmosphere at 1200C, resulting in the coking of the novolak resin.
The bulk density of the plates thus pro~uced amounted to 0,41 ~/cm3.
Their cold-bending strength lay at 2,2 N/mm2.
Example Z
The procedure of Example 1 was repeated, but using 70 parts by mass of the mineral fibres used in Example 1, 24 parts by mass of resol resin ~and 6,0 parts by mass of the silica used in Ex~mple l. Flocculation was again carrie~ out by means of a cationic starch, the latter being added, calculate~ on solid content, in a quantity of 0,lZ5 parts by mass.
Tlle further processing was carried out in accordance with the proced~lre under ~alnple 1. Plates havin~ a bulk density of about 0,4 ~ 3 were obtaine~. -ample 3 ' 85 palts by mass of the mineral fibres used in Exan~le 1 ~Id 15 parts by mass of the novolak resin used in xample 1 were added to a 0,5% by Inass suspensioll ;in ~ater (consistency = ~,5%). Agaill, there was precipitation o the novolak resin Oll the ceramic ~ibres, usin~ the cationic starch used in ~xample ]. Subsequently, plates were again :
.,.,.. ~, :, 1 3 ~ 6 manufactured whi ch were heat-treated at 380C. lhis resulted in a partial pyrolysis of the novolak resin.
The bulk density of the plates amounted to 0,4 g/cm3.
A suspensioll was preyared with l.5~ by mass of mineral fibres ~Id 30% by mass of novolak resin accordiIlg to Example l, with the additional components ~uartz pow~er below 0,09 mm at 33% by mass and colloi.dal silicic acid at 12% by mass. Metalli.c aluminium powder having a ~rain size of less than 0,09 mln at 8% by mass was also added as antioxidant agellt. The flocculation of the suspension was achieved with a total of 2~ by mass of starch. The plates obtai.ned from the flocculated suspensiorl accordin~ to the screen mould process, and after dryin~ and coking at 800C, had a bulk density of 0,62 g/all3 and a cold-bendin~
strength of 3,2 N/n~n2.
Example 5 A suspenslon, having the same components~as in Example 4j was prepared,1.5% by mass of rapid-hardenin~ cement ~70% by mass Al2O3 contellt) was aiso added~in ad~i.tion to 5% by mass of mineral fibres, 48% by mass of quartz powder, 25% by mass of novolak resin, 2% by mass of colloidal sil~clc~acid and 5% by mass of elementary aluminium powder. After the vacuum-scleenin~ process, a plate having a bulk densi.ty of 0,95 g/cm3 .
13~92~
was obtained. The cold-bending strengtll amo~ted to ~,2 N/mm~ ater coking at 800C.
Exall le 6 further suspension was prey~red using the same componenfs as in Ex~nple 4, the quartz powder however being replaced by finely ground sintered alwnina, having a grain size of less than 0,09 nun. ~dded to the suspension were: 20% by mass of mineral ibres, ~5% by m~ss of fine alwnina, lO~o by mass of novolak resin, ]5% by n~ass of colloidal silicic acid, and 8% by mass of elementary silicon. In ad~ition, a portion o~
2% by mass of starch was used. After flocculation and Wit]l the aid of a screen mould, plates were produced from the dispersion, the plates were subse~uently dried and heat-treated at 800C.
The bulk density of the ~lates amounted to 0,7 g/cm3.
:
,...
.
This invention relates to a process for the m~lufacture of carbon-bound shayed parts which contain mineral fibres.
The invention concerns a process for the manufacture of shaped parts which contain r~fractory or fireproof mineral fibres, in which process the mineral fibres are embeddea in ~ carbonaceous matrjx. The invention also conce ms sllaped parts which are carbon-bound and which contain mineral fibres m~lufactured accordin~ to this process.
Carbon-bo~l~ shaped parts containing mineral ibres are kno~. Thus, a moulde~ body composed of a heat-insulating material and a process for its manufacture are described in DE 30 09 182 C2. According to this m~lufacturillg process, carbonaceous substances, e.g. solid resins, either are mixed with the mineral fibres which form 15 to 60% by mass of the material of the moulded bod~, or the fibres are immersed in liqui~
carbonaceous substances. Synthetic resins, bituminous mineral oil or tar may be used as the carbonaceous substances. The pyrolysis, or cracking, of the carbonaceous substances tllen take place after shaping.
In addition, a refractory, heat-insulating material which is composed of aluminium silicate fibres and a binding agent, and which con~ains particulate, refractory fillers, is know~l from DE-~S 19 47 904. A
furtller plate material whlch contains ceramic fibres, and a process for its productioll~ are described in EP 00 77 444 Al. The manufacture of this~ plate material also takes ~lace from an aqueous slurry of the flbres. Such a slurry contains inorganic, refractory fillers. A
flocculation agent or a precipitation agent is used in the form of a cationic polyacryl ~nide. A process for the manufacture of light-weigll ', .: , ~, " ,,, ~ , . . .
. --3--13~926 shaped bodies composed of ceramic fibres, finely divided refractory matter, inorganic binding a~ents and conventional additives, is known from ~ 34 36 781, wherein, a two-stage flocculent-precipitation yrocess and a mixing of the two ~locculated dispersions takes place. Accordillg to thi.s state of the art, using a di.spersion of the fibres for shaping, with or without 1Occulatioll, however, no shaped bodies which have a carbon bond are manufactured.
;
The present illvention provides a process for the manufacture of shaped parts ~hich contain refractory or fireproo~ milleral ~ibres, in w}lich process the mineral fibres are embedded in a carbonaceous matrix, wherein finely particled pitch, tar or resol or novolak resins are flocculated from an aqueous suspension onto the mineral fibres present in the aqueous suspension, a green shaped part is produced from the suspension, and the green shaped part is dried and subjected to pyrolysis at temperatures of from 350~C to 1300~C. The parts produced have a carbon bond and carbonaceous phase. The process is simple in its execution and facilitates the manufacture of such shaped parts, ~he bulk density of whi.ch can be widely adjusted. In particular a low bulk densi.ty can be ac!lieved.
;
Accolding to a preferred embodiment, finely particled refractory or fireproof substances and/or inorganic binding agents and~or hydraulically setting refractory cements are also flocculated onto the minelal fibres in the suspension.
, .. .
.
13~26 As a result hereof, it is possible to re~ulate the properties of the resulting refractory shaped parts and, also, to control their bulk density. ~loreover, the advantage arises, when usin~ inor~anic binding agents, that a relatively great strength can be achieved in ~l intermediate temperature range of 40U to 800C and, when using hydraulically setting refractory cements. A further advanta~D is that, after drying, a high green stren~t}l of the shaped body is already achieve~.
Jn a furtller preferred elllbodim~nt, a cationic s~arch is used as flocculation agent.
In the process according to the invention, the mineral fibres may be added in a quantity of from 5 to 90% by mass, the pitch, the tar or the resol or novolak resin in a quantity of from 10 to 30, preferably 15 to 25~ by mass, the finely particled refractory or fireproof substances in a quantity of from 5 to 70~ by mass, the inorganic bindi.ng agents in a quantity of from 5 to Z5% by nlass, and the hydraulically setting refractory cements in a quantity of Erom S to 20% by mass, these speclfications relating to the dried shaped part which has not yet been subjected to pyrolysis.
lhe refrnctory or f~reproof mlneral fibres used in the process according to ~he invention can be any milleral fibres, preferably fibres of silicon dioxi.de, of aluminium oxide, the A12O3 con~ent of which is preferably at least 72%, or of an alumi.nium silicate material, in parti.cular having at least 40 to 60% of Al~03 and 6U to 40% of SiO2.
~.;
::, ~' , .. ~ . ...
131~92~
i`he diameter of these mineral fibres is preferably smaller than 15 l~n, i.e. so small that breaking of the fibres when tlley are processed need not be feared. Jn view o the conditions under which such fibres are produce~, their di~neter is usually greater than 1 ~m.
Tlle length of these fibres conveniently should exceed 3 mm, so that the fibres can fulfill their funstion as mechanical reinforcillg Wit}lill the shaped body. lhere is no critical maxim~n value for the length of the fibres, with the exception of the critical len~th determjned by the m~mler of manufacture of tlle fibres.
In the process according to the invelltion, a finely particled pitch, tar or resol or novolak resin is used. These are con~nercially known substances. The maxim~n grain size o these ~inely particled carbonaceous substances is, preferably, 0,09 nnn The finely particled curbonaceous substances cause the developmei~t of the strength of the shaped parts durin~ drying at temperatures exceeding 30C. The fi3lely particled carbonaceous substances in addition fonn a carbonaceous phase, i.e. accwnulations and coatings fo~n Oll the mineral fibres and, in the case of a large component of carbonaceous substances, a continuous carbonaceous matrix is achieved. Ater pyrolysis by heat treatmellt of the shaped part, the carbonaceous phase results in the improved resistance to abrasion and resistance to corrosion.
~; Flocculatioll agents are used in the process. These are anionic or cationlc substances, cationic starcbes being preferTed. The cationic polyacrylamide flocculation agellls used in ~P 00 77 4~ can, however, ~, , .. . ~ ,., . ~ . .
also be elllployed, as can other cationic flocculatioll agents, kno~m yer se, in the form of polyelectrolytes, e.g. methacrylate. These cationic flocculatjon agents are usually prepared in the fonn of a solution having a concelltratioll of 0,5 to 1% by mass, and are further diluted before use to solutions of OJOS to 0,1% by mass; a similar situation arises in respect of aniol]ic agents, such as anionic polyeletrolytes based on acrylic amide.
According to a further preferred embodimeJlt, finely particled, refractory or fireproof substances are flocculated OlltO the mineral fibres in the aqueous suspension, together with the pitch, tar or resol or novolak resin. Such finely particled or finely divided refractory matter having a grain size of~ 0,09 nm can be convelltional refractory matter, e.g. fireclay, bauxite, alumina, carundum, zirconiu~ dioxide, zircon mineral, magnesium oxide, cordierite, carbon, i.e. graphite, coke, silicon carbide and/or chrolni~ oxide. Such finely particled refractoly matter can be used si~lgly or in the form of mixtures.
In addition, in the process according to the invention, an inorganic bindiJlg a~ell-t can also be flocculated together Wit]l the pitCll, tar or resol or novolak resin. Such inorganic binding agents may be colloi~al SiOz or colloidal A12O3. The strength of the shaped parts is further improved by means of these inorganic binding agellts.
Ill the same way, hydraulically setting refractory cemen~s, e.g.
alwninous cement or rapid-hardening cements having a high A12O3 conten~
can be flocculated together with the pitch, tar or resol or novolak . ,~ ., .,, ~.. . . .. . .
131~92~
resin. The shaped part obtains its strength as a result of the setting of the refractory cemeIlt. The finely particled refractory matter, iIlorganic binding agents and hydraulically setting refractory cemeIlts can, in each case, be used individually or in any desired mixture or combination.
In the process according to the invention, mineral fibres in the suspension are pre$erably used in a cluwltity of from 5 to 15~ by mass or 6~ to 70% by mass. Shaped parts having a low mineral-fibre component are distinguished by a relatively low speci~ic gravity an~ a low theImal conductlvity, while manifesting good strength ~Id resistance to wear.
In the case of a lar~er mineral-fibre component, there is, at ~irst, only~a slight reduction in the specific gravity. At the same tin~e, the strength is gre~tly reduced, with the result that such compositioIls of the suspensioIl should not be regarded as be~ng particularly suitable.
It is only when there is a predomin~lt co~nponent of mineral fibr~s from about 6~% by mass, that shape~ parts are obtained in advantageous manner which have a very low thennal conductivity, low specific gravity and relatively high strength.
.
In order to protect the carbon~ceous phase in the shaped parts against .
corrosion by way of oxidation, elementary silicon or metallic aluminium in the folm of a powder having a grain size below 0,09 nm can be illtroduced into the susyension as antioxida~lt agents during the mallufacture of the shaped paTts~ In the~course ~f the pyrolysis of the shaped~parts by means of heat treatment, the ~ltioxidant agent partially .
~ ;; reacts~wlth the carbon to form carbides.
; ~
::
::
,~.,,,~- : ~ ... .
. ~ , 13~926 In the process according to the invention, as a first step, an aqueous suspension of the mineral fibres is prepared. Such a suspension usually has u consistellcy of 0,5 to 3% by mass. Subsequent to the preparation of this a~lueous suspension of the milleral fibres, the finely par~icled pitch, tar or resol or novolak resin is scattered into this suspension and mi~ed well therewith. In like manner, finely particled refractory matter, inor~anic binding agents and hydraulically setting refractory cemellts are, optionally, added In this stage. Subse~uently, the solution of tlle flocculation agent described above is added, usually in a qu~tity of 5 g o~ the flocculation agent, calculated as solid matter, per 100 kg of the suspension.
Subsequently, the green shaped body is moulded from the dispersion which colltaills the flocculated suspension, in the usual manner. The dispersion is fillecl into a mould which has a perforated bottom. The dispersioll is dewatered by means of the draining of the liquid through the perforated bottom, this process possibly being assisted by establishing a vacuwn, and possibly by additional pressing power, ancl the shaped body is formed.
Ihe shaped bodies are usually dried at temperatures of from 110 to 180C. After dryin~, the shaped parts are treated at temperatures of between 350C up to temperatures of~ 1300C. A partial or com~lete pyrolys~s, or cokin~, of the pitch, tar or resol or novolak resins, takes place. This results in the fonnation or intensification of tlle carbon-binding of t}le mineral fibres and the furtller development of the carbonaceous phase. In the case of a high component of the carbonaceous ::
. ,~ .. .
9 ~ ~ -yhase, the milleral fibres can be en~.bedded in it, as in a carbonaceous matri~. The temperature of the heat treatnlent in each case depends on the finely particled pitch, tar or resol or novolak resin used, and furthemlore whether a shayed part is required which has already been subjected to pyrolysis up to 10~%, or whether a subsequent pyrolysis of the shaped part is possible or desired when in use by the end-user.
The heat treatment for the pyrolysis, or coking, of the pitch, tar, resol or novolak resin is undertakell in the maluler kno~l per se in llOII-OXi.diZillg a~mosphere, i.e. in an inert gas, such as nitrogen, car~on monoxide or carbon dioxide.
The invention will be described in more detail with reference to the ollowing non-limitin~ E~amples.
~xan~le ]
63 parts by mass of mineral fibres having an A1203 content of 47% by mass, remainder SiO2, were reduced to a 1% suspension with water with the assist~lce of a powerful stirring apparatus. To this were added 7,5 parts by mass colloidal sllica, 23 yarts by mass of a finely particled solid novolak resin having an average grain size of 2 to 3 ~, and 6,5 parts by mass o~ finely particled alumina~(A1~03~ having a grain size of ~10 ~m, and were also well stirred in the suspensioll. Subsequently, a 0,5% solution of a cationic starch was added, causing the flocculation of the novolak resin arid the finely particled refractory matter and of the inorganic binding agent. The solution was dewatered on a screen , ~31~
mould with the creation of a vacuum to fonn plates, and these plates were subsequently dried at lZ0 to 150C. These plates were then heat-treate~ in a non-oxi~izi-l~ atmosphere at 1200C, resulting in the coking of the novolak resin.
The bulk density of the plates thus pro~uced amounted to 0,41 ~/cm3.
Their cold-bending strength lay at 2,2 N/mm2.
Example Z
The procedure of Example 1 was repeated, but using 70 parts by mass of the mineral fibres used in Example 1, 24 parts by mass of resol resin ~and 6,0 parts by mass of the silica used in Ex~mple l. Flocculation was again carrie~ out by means of a cationic starch, the latter being added, calculate~ on solid content, in a quantity of 0,lZ5 parts by mass.
Tlle further processing was carried out in accordance with the proced~lre under ~alnple 1. Plates havin~ a bulk density of about 0,4 ~ 3 were obtaine~. -ample 3 ' 85 palts by mass of the mineral fibres used in Exan~le 1 ~Id 15 parts by mass of the novolak resin used in xample 1 were added to a 0,5% by Inass suspensioll ;in ~ater (consistency = ~,5%). Agaill, there was precipitation o the novolak resin Oll the ceramic ~ibres, usin~ the cationic starch used in ~xample ]. Subsequently, plates were again :
.,.,.. ~, :, 1 3 ~ 6 manufactured whi ch were heat-treated at 380C. lhis resulted in a partial pyrolysis of the novolak resin.
The bulk density of the plates amounted to 0,4 g/cm3.
A suspensioll was preyared with l.5~ by mass of mineral fibres ~Id 30% by mass of novolak resin accordiIlg to Example l, with the additional components ~uartz pow~er below 0,09 mm at 33% by mass and colloi.dal silicic acid at 12% by mass. Metalli.c aluminium powder having a ~rain size of less than 0,09 mln at 8% by mass was also added as antioxidant agellt. The flocculation of the suspension was achieved with a total of 2~ by mass of starch. The plates obtai.ned from the flocculated suspensiorl accordin~ to the screen mould process, and after dryin~ and coking at 800C, had a bulk density of 0,62 g/all3 and a cold-bendin~
strength of 3,2 N/n~n2.
Example 5 A suspenslon, having the same components~as in Example 4j was prepared,1.5% by mass of rapid-hardenin~ cement ~70% by mass Al2O3 contellt) was aiso added~in ad~i.tion to 5% by mass of mineral fibres, 48% by mass of quartz powder, 25% by mass of novolak resin, 2% by mass of colloidal sil~clc~acid and 5% by mass of elementary aluminium powder. After the vacuum-scleenin~ process, a plate having a bulk densi.ty of 0,95 g/cm3 .
13~92~
was obtained. The cold-bending strengtll amo~ted to ~,2 N/mm~ ater coking at 800C.
Exall le 6 further suspension was prey~red using the same componenfs as in Ex~nple 4, the quartz powder however being replaced by finely ground sintered alwnina, having a grain size of less than 0,09 nun. ~dded to the suspension were: 20% by mass of mineral ibres, ~5% by m~ss of fine alwnina, lO~o by mass of novolak resin, ]5% by n~ass of colloidal silicic acid, and 8% by mass of elementary silicon. In ad~ition, a portion o~
2% by mass of starch was used. After flocculation and Wit]l the aid of a screen mould, plates were produced from the dispersion, the plates were subse~uently dried and heat-treated at 800C.
The bulk density of the ~lates amounted to 0,7 g/cm3.
:
,...
.
Claims (11)
1. A process for preparing a shaped article containing refractory or fireproof mineral fibres embedded in a carbonaceous matrix which process comprises:
(a) flocculating fine particles of pitch, tar or resol or novolak resin from an aqueous suspension thereof onto said mineral fibres present in aqueous suspension to yield a flocculated particle-mineral fibre composition;
(b) dewatering and shaping the composition to yield a dewatered, and shaped composition;
(c) drying the shaped composition resulting from step (b);
(d) pyrolysing the dry shaped composition resulting from step (c) at a temperature of from 350°C to 1300°C to yield a shaped article containing said mineral fibres embedded in a carbonaceous matrix.
(a) flocculating fine particles of pitch, tar or resol or novolak resin from an aqueous suspension thereof onto said mineral fibres present in aqueous suspension to yield a flocculated particle-mineral fibre composition;
(b) dewatering and shaping the composition to yield a dewatered, and shaped composition;
(c) drying the shaped composition resulting from step (b);
(d) pyrolysing the dry shaped composition resulting from step (c) at a temperature of from 350°C to 1300°C to yield a shaped article containing said mineral fibres embedded in a carbonaceous matrix.
2. A process according to claim 1 wherein a finely particled refractory or fireproof substance, an inorganic binding agent or a hydraulically-setting refractory cement is additionally flocculated onto said mineral fibres in aqeuous suspension.
3. A process according to claim l wherein the floccu-lating agent comprises cationic starch
4. A process according to claim 1, 2, or 3 wherein the dry shaped composition is pyrolysed at a temperature of from 400°C to 800°C.
5. A process according to claim 1, 2 or 3 wherein the suspension comprises:
(i) 5 to 90% by mass of mineral fibres;
(ii) 10 to 30% by mass of pitch, tar or resol or novolak resin;
(iii) 5 to 70% by mass of a finely particled refractory or fireproof substance;
(iv) 5 to 25% by mass of an inorganic binding agent;
(v) 5 to 20% by mass of a hydraulically-setting refractory cement, the proportions being relative to the mass of the dry shaped composition which has not been pyrolysed.
(i) 5 to 90% by mass of mineral fibres;
(ii) 10 to 30% by mass of pitch, tar or resol or novolak resin;
(iii) 5 to 70% by mass of a finely particled refractory or fireproof substance;
(iv) 5 to 25% by mass of an inorganic binding agent;
(v) 5 to 20% by mass of a hydraulically-setting refractory cement, the proportions being relative to the mass of the dry shaped composition which has not been pyrolysed.
6. A process according to claim 1, 2 or 3 wherein the suspension comprises:
(i) 5 to 15% or 60 to 70% by mass of mineral fibres;
(ii) 15 to 25% by mass of pitch, tar or resol or novolak resin;
(iii) 5 to 70% by mass of a finely particled refrac-tory or fireproof substance;
(iv) 5 to 25% by mass of an inorganic binding agent;
(v) 5 to 20% by mass of a hydraulically-setting refractory cement, the proportions being relative to the mass of the dry shaped composition which has not been pyrolysed.
(i) 5 to 15% or 60 to 70% by mass of mineral fibres;
(ii) 15 to 25% by mass of pitch, tar or resol or novolak resin;
(iii) 5 to 70% by mass of a finely particled refrac-tory or fireproof substance;
(iv) 5 to 25% by mass of an inorganic binding agent;
(v) 5 to 20% by mass of a hydraulically-setting refractory cement, the proportions being relative to the mass of the dry shaped composition which has not been pyrolysed.
7. A process according to claim 1, 2 or 3 wherein the maximum grain size of the particles of pitch, tar or resol or novo-lak resin is 0.09 mm.
8. A process according to claim 1, 2 or 3 wherein the mineral fibres are fibres of silicon dioxide or aluminum oxide.
9. A process according to claim 1, 2 or 3 wherein the mineral fibres comprise at least 72% Al2O3 or comprise an aluminum silicate, said aluminum silicate comprising 40 to 60% Al2O3 and 60 to 40% SiO2.
10. A process according to claim 1, 2 or 3 wherein the average diameter of the mineral fibres is between 1 and 15 micro-metres and the average length is at least 3 mm.
11. A shaped article comprising the pyrolysis product of dried shaped composition of refractory or fireproof mineral fibre upon which, prior to drying, fine particles of pitch, tar or resol or novolak resin have been flocculated.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873716729 DE3716729A1 (en) | 1987-05-19 | 1987-05-19 | METHOD FOR THE PRODUCTION OF CARBON-BASED MOLDED PARTS CONTAINING MINERAL FIBERS |
| DEP3716729.4 | 1987-05-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1315926C true CA1315926C (en) | 1993-04-13 |
Family
ID=6327864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000567094A Expired - Fee Related CA1315926C (en) | 1987-05-19 | 1988-05-18 | Process for the manufacture of carbon-bound shaped parts which contain mineral fibres |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0291646A1 (en) |
| JP (1) | JPS63297271A (en) |
| KR (1) | KR880013837A (en) |
| CN (1) | CN1019968C (en) |
| CA (1) | CA1315926C (en) |
| DE (1) | DE3716729A1 (en) |
| ZA (1) | ZA882164B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3910860A1 (en) * | 1989-04-04 | 1990-10-11 | Gruenzweig & Hartmann | MINERAL WOOL BASED MOLDING AND METHOD FOR PRODUCING THE SAME |
| FR2665168B1 (en) * | 1990-07-30 | 1994-03-25 | Rhone Poulenc Chimie | COMPOSITION COMPRISING A SUCCINOGLYCANE. |
| FR2665167B1 (en) * | 1990-07-30 | 1994-03-25 | Rhone Poulenc Chimie | COMPOSITION CONTAINING A POLYSACCHARIDE OBTAINED BY MICROBIAL FERMENTATION. PA |
| GB0305517D0 (en) * | 2003-03-11 | 2003-04-16 | Carbon Applic Technology Ltd | Refractory cement castables |
| JP5448857B2 (en) * | 2010-01-05 | 2014-03-19 | 積水化学工業株式会社 | Thermally expandable refractory annular molded body for piping and manufacturing method thereof |
| DE102019212441A1 (en) * | 2019-08-20 | 2021-02-25 | BKRZ GmbH | Process for recycling insulation wool, device for processing insulation wool, fiber-reinforced foam, fire-resistant wood-based material as well as a process for producing a fire-resistant wood-based material |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1204472A (en) * | 1966-08-09 | 1970-09-09 | Foseco Trading Ag | Heat-insulating shaped compositions |
| GB1283692A (en) * | 1968-09-25 | 1972-08-02 | Foseco Int | Refractory heat insulating materials |
| GB1410043A (en) * | 1972-10-19 | 1975-10-15 | Foseco Trading Ag | Refractory heat insulating materials |
| US4152482A (en) * | 1978-05-10 | 1979-05-01 | The United States Of America As Represented By The United States Department Of Energy | Anisotropic fibrous thermal insulator of relatively thick cross section and method for making same |
| FR2461690B1 (en) * | 1979-07-19 | 1985-08-16 | Europ Propulsion | HIGH TEMPERATURE THERMAL INSULATION MATERIAL AND MANUFACTURING METHOD THEREOF |
| US4407969A (en) * | 1981-07-16 | 1983-10-04 | The Babcock & Wilcox Company | Flexible refractory composition |
| ZA825689B (en) * | 1981-10-19 | 1983-06-29 | Kennecott Corp | Ceramic fiber board |
-
1987
- 1987-05-19 DE DE19873716729 patent/DE3716729A1/en active Granted
-
1988
- 1988-03-03 EP EP88103252A patent/EP0291646A1/en not_active Withdrawn
- 1988-03-25 ZA ZA882164A patent/ZA882164B/en unknown
- 1988-04-04 KR KR1019880003792A patent/KR880013837A/en not_active Application Discontinuation
- 1988-05-13 JP JP63115013A patent/JPS63297271A/en active Pending
- 1988-05-14 CN CN88102823A patent/CN1019968C/en not_active Expired - Fee Related
- 1988-05-18 CA CA000567094A patent/CA1315926C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0291646A1 (en) | 1988-11-23 |
| DE3716729C2 (en) | 1989-10-26 |
| DE3716729A1 (en) | 1988-12-01 |
| KR880013837A (en) | 1988-12-22 |
| JPS63297271A (en) | 1988-12-05 |
| CN88102823A (en) | 1988-12-07 |
| CN1019968C (en) | 1993-03-03 |
| ZA882164B (en) | 1988-10-03 |
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