CN105777134A - Manufacturing method for ceramic composite material - Google Patents

Abstract

The invention relates to a method for production of a ceramic composite from a polycrystalline ceramic material formed from an alumina parent metal. The method provides a filling material, wherein at least one part of the filling material has a silicon source coating layer, and the silicon source coated filling material is different from an initial filling material in composition; and the silicon source has intrinsically doped properties. According to the invention, a molten parent metal adjacent to the filling material reacts with an oxidizing agent to form an oxidation reaction product which permeates through the adjacent filling material, so the ceramic composite is formed.

Description

A kind of manufacture method of ceramic composites

The present invention is under H.DanielLesher et al. name, with " manufacture method of ceramic composites " for topic, in the part continuation application of the application No908473 of JIUYUE in 1986 submission on the 17th.

Put it briefly, the present invention relates to the method manufacturing ceramic composites.It is more particularly related to the method producing ceramic composites to such a, namely with a kind of oxidation reaction product grown from aluminum base metal, penetrate into by the filler of silicon source coating with intrinsic doping character.

In recent years, pay attention to day by day is used as pottery to continue to use in history the structural material of metal.The motive power of this attention is in that pottery has some character to be better than metal, for instance in anti-erosion, hardness, elastic modelling quantity and heat-resisting ability etc..

Currently, production intensity is higher, more reliably concentrate on the advanced processing method of (1) exploitation monoblock type pottery with the research of the ceramic of richer toughness；(2) new composite, especially ceramic matrix composites are developed.So-called composite structure refers to such a structure, and it contains heterogeneous material, heterogeneous body or the goods that the material being closely linked by two or more is made, so that corresponding composite possesses required character.Such as, the one in material two kinds different can be embedded in alternative substrate so as to combine closely.The composite of a kind of ceramic substrate is then closely combined with the filler of one or more different granular, fibrous and bar-shaped or the like geometries.

In the shaping and manufacture of ceramic matrix composites part, various suitable material had been adopted to be used as filler.This kind of filler utilize form have threadiness, lamellar, granular with must shape etc..The material of this respect, for instance include some oxide (single or mixing) of aluminum, hafnium, titanium, zirconium, yttrium and silicon, nitride, carbide or boride.Some different materials being used as filler known, such as carborundum and silicon nitride, in high-temperature oxidation environment (such as more than 850 DEG C) though in unstable in itself, but demonstrate under such circumstances and there is relatively low degradation kinetics character.

The known restriction of several respects or difficulty is there is, for instance the adaptability changed proportionally, the ability producing complicated shape goods, the satisfied finally character that application is required and cost etc. when with pottery substituted metal.Existing several belong to proprietary pending application same as the application and overcome some aforesaid restriction or difficulty, and provide and can reliably produce ceramic material and include the new method of composite material element.Under MarcS.Newkirk et al. name, with " new ceramic material and manufacture method thereof " for topic, in the pending U.S. Patent application No818943 that January 15 in 1986 proposes, say classification, disclose a kind of important method.Disclosed in these several applications, from the method that self-self-supporting ceramic bodies is prepared in the growth of a kind of parent metal oxidation product.A kind of oxidation reaction product of formation is reacted in motlten metal and vapour-phase oxidation agent, and namely this kind of metal shift to above-mentioned oxidant by this oxidation reaction product, develops into a kind of polycrystalline ceramic body continuously at this.By adopting the adulterant of a kind of alloying, just can accelerate said process, for instance the aluminum of Oxidation Doping magnesium and silicon forms the situation of alpha-aluminium oxide ceramic structure in atmosphere.As MarcS.Newkirk et al., with " composite ceramic articles and manufacture method thereof " for topic, in described in the pending U.S. Patent application No822999 that on January 17th, 1986 submits to, dopant material is applied to the surface of base metal, has made preceding method be improved.

Above-mentioned this oxidative phenomena is applied, at MarcS.Newkirk et al., with " composite ceramic articles and manufacture method thereof " for topic, in arriving described in the pending U.S. Patent application No819397 that on January 17th, 1986 proposes in producing composite ceramic body.Disclosed in these several applications more such produce the new method of self-supporting ceramic composites, namely the oxidation reaction product from base metal gained is grown in a permeable filling body, thus a kind of ceramic substrate has just penetrated among this kind of filler.But, the composite bodies so obtained there is no that determine or predetermined geometry, profile or configuration.

A kind of production has the method for the composite ceramic body of predetermined geometry or shape, has been disclosed in the pending U.S. Patent application No861025 that on May 8th, 1986 proposes.According to the method in this U.S. Patent application, the oxidation reaction product grown penetrates in a permeable preform towards a surface-boundary direction determined.Disclosed as proposing on May 8th, 1986 in pending U.S. Patent application No861024, it is discovered that by providing a kind of barrier layer for this kind of preform, to be more easy to the shape shaping high fidelity (Hi-Fi).Method in this application, for establishing the barrier layer on border or surface, has produced the supporting ceramic bodies having definite shape by the oxidation reaction product of a kind of base metal grows into one and this metal separate, including the ceramic composite having definite shape.A kind of method preparing the composite ceramic body with the cavity that can reversely copy formpiston shape or base metal shape, then it is disclosed in the pending U.S. Patent application No823542 that on January 27th, 1986 proposes, and in the pending U.S. Patent application No896157 that on August 13rd, 1986 proposes.

Entire disclosure in these pending patent applications above-mentioned, as reference, has been integrated in the application.

The present invention, briefly get on very well, provide a kind of method for producing ceramic composite, this ceramic composite includes the ceramic substrate being carried out (including a kind of vapour-phase oxidation agent) oxidation reaction gained by molten aluminum base metal and a kind of oxidant, and include at least when starting with a kind of filler for silicon source (definition sees below) institute coating that this substrate is permeated.The composition that this silicon source has is different from the original composition of this filler, and this silicon source is reduced by this molten parent metal at least partially under these process conditions or dissolves.When the coating in this silicon source is heated, and preferably but not necessarily in an oxygen containing environment, to be heated to suitable temperature, it be just provided with can accelerated oxidation reaction intrinsic doping character, the overwhelming majority is unchanged or remaining fillers then play the effect of filler and join in the substrate grown, after as will be described in more detail.

When producing self-supporting ceramic composite, first to form a kind of packed bed or filling body so that it is in part or all of ingredient with the coating of a kind of silicon source.The composition in this kind of silicon source is different from the original composition of this filler.This kind of filler is at least partly covering with barrier layer, and the latter is at least some and separates with aluminum base metal, for determine ceramic substrate surface or border.

This filler being loaded with silicon source can be combined use by stratification form, the form of bond or the form of preforming preform with other filler, it to be close to aluminum base metal location or directed, being formed of oxidation reaction product being occurred in the direction towards oxidant Yu filler, then occurring in the direction towards this barrier layer if having employed barrier layer.Packed bed or preform should have enough permeabilitys, to allow or to allow that oxidation reaction product can grow in above-mentioned bed, allow the oxidant energy infiltrated preform of this gaseous state to contact with motlten metal simultaneously.This kind of base metal is then heated to one higher than its fusing point but lower than the temperature of this oxidation reaction product fusing point, to form a kind of molten metal body.At this temperature or in this temperature range, namely this motlten metal forms oxidation reaction product with oxidant reaction.At least part of this oxidation reaction product remains and contacts with motlten metal and oxidant and be between both, so that motlten metal is by oxidation reaction product and towards oxidizing agent migration and contact, make this oxidation reaction product continue the interface between this oxidant and the oxidation reaction product that is previously formed to be formed, thus penetrating in contiguous filler.Above-mentioned reaction to proceed enough time, not oxidized base metal or the dopant component that partial filler these metal components above-mentioned are then distributed across in polycrystalline material is at least penetrated into the polycrystalline material being made up of oxidation reaction product and one or more metal component, should be realized that, this kind of polycrystalline matrix material likely substituted metal phase and space occurs or demonstrates porous, but the percent volume of this hole depends greatly on so some conditions such as temperature, time, adulterant and base metal type.If having have employed barrier layer, as long as there being enough base metals, this ceramic body will continue to grow into barrier layer place.

As illustrated in these pending patent applications aforementioned, application dopant material is conducive to or promotes above-mentioned oxidation reaction process.Silicon is a kind of Effective Doping agent of aluminum base metal, especially in conjunction with when having other adulterant, and can use base metal from outside, and effective source of such a adulterant is then silicon dioxide.Under the process conditions of the present invention, the aluminum base metal reduction that is melted as a kind of silicon compound of this silicon source (such as silicon dioxide) and form aluminium oxide and silicon.So, the silicon compound that this kind is coated on filler is a kind of effective adulterant promoting the development of this oxidation reaction product or growth.Such as, carborundum in atmosphere with high temperature under time surface or surface on can aoxidize and form a kind of silicon dioxide film, thus carborundum not only serves as filler due to it but also can serve as doped source, just become a kind of particularly effective filler.Such silicon dioxide film is the reduction of molten aluminum base metal, generates a kind of silicon dopant, promotes that polycrystalline matrix is by this kind of silicon carbide filler growth.In addition, silica dioxide coating on silicon-carbide particle also has the advantage that, namely in this substrate formed course of reaction, it makes the local silicon concentration in the aluminum base metal not aoxidized improve, thus reducing the trend forming Al4C3 in the growth course of this substrate.Al4C3 is undesirable, because being unstable under its temperature conditions of occurring in usual surrounding air, causes discharging methane and destroying the structural property of final composite.

From the purpose of the present invention, it is discovered that this kinds of oxidation reaction above-mentioned preferably carries out in oxygen containing environment, and it is used as the dopant material of this kind of parent metal oxidation reaction with silicon source coating.All the other filler parts below this coating, owing to forming difference, essentially no change, and play the filler effect in composite material element.Such as, this kind of filler can be loaded with a kind of silicon compound that can reduce for motlten metal, or, this kind of filler can apply with being melted the silicon that metal dissolves.Should be realized that, it is possible to most this silicon sources are used as a kind of adulterant, or only its part is used as adulterant, and remaining part is together with filler and be that host material is embedded into.Some filler, for instance carborundum, will be oxidized to SiO2 under the high temperature of this process, and the condition in this process will be controlled to limit this oxidation, in order to produce the silica dioxide coating that can reduce for molten parent metal.If desired, can being added on this filler by a kind of independent coating material, this coating material can produce silicon compound when heating.The coating of this eka-silicon source such as silicon compound, it is possible to by first pre-burning or heat suitable filler and formed or produce in oxygen-containing atmosphere.The above cated filler of this pre-fired, even if using with as a kind of filler.For example, it is possible to be coated with the compound of a kind of siliceous fertile material or tetraethyl orthosilicate etc with silicon-carbide particle or alumina particle, manufacture a kind of preform.Then by this preform pre-burning or heating in air, and on the silicon-carbide particle or alumina particle of this preform, the oxidation film of a kind of silicon dioxide is formed.Such preform then just can as the raw material of a kind of ceramic composite in the doped material source with intrinsic.On the other hand, this carborundum with siliceous coating or alumina particle can be also used in the anabolic process of filler and base metal, and silicon dioxide film now or silica dioxide coating, can be formed in position in former in having oxygenous oxidation reaction process.The original composition of this kind of filler particles (such as carborundum or the granule of aluminium oxide) then remains unchanged, and plays the effect of filler in composite material element.

According to this composite material element that the present invention prepares, to certain thickness, can show that substantially uniform character at its whole cross section, and this is to be difficult in order to the common process of front production ceramic component.The present invention is used for producing the technique of above-mentioned material part it also avoid shortcoming high in conventional ceramic production method and include preparing high-purity uniform fine powder material and by sintering, hot pressing or isostatic pressed etc method so as to densification.

This kind of product of the present invention is suitable as maybe can be processed as following all commodity, including having, but it is not limited to, industry, building industry and technology apply closely-related ceramic body with electrical property, abrasion character, thermal property, structural property or some other characteristic；But class cycle stock or the waste material produced possibly as unwanted side-product not included in motlten metal processing procedure.

As follows as the term definition used in this manual and in the appended claims: " ceramic body " should not be construed as limited to that ceramic body of traditional sense irrelevantly, the i.e. completely nonmetal that ceramic body with inorganic material composition, and refer to a kind of object being mainly pottery for its composition or fundamental property, wherein may also include one or more metal component a small amount of or substantial amounts of, the latter derives from base metal or is produced by oxidant or a kind of adulterant, by volume calculate, most of situations are typically in the scope of about 1 to 40%, and may also include the metal of more amount.

" oxidation reaction product " generally refers to the aluminum under any state of oxidation as base metal, now this metal provided electronics or with another kind of element, compound or this combination body, share electronics.Accordingly, the one " oxidation reaction product " under this definition also includes the product of aluminum metal and a kind of oxidant (this kind of oxidant such as described herein).

" oxidant " refers to one or more suitable electron acceptor or electronics shares, can be a kind of solid, liquid or gas (steam) or certain combination (such as solid and gas) between them under corresponding process conditions.

" base metal " refers to aluminum, it is the precursor of multi-crystal oxidation reacting product, including quite pure aluminum, the commercially available aluminum with impurity and/or alloying constituents, or the such a alloy of aluminum, it is wherein account for the overwhelming majority or maximally efficient component in forming oxidation reaction product as the aluminum of parent.

" silicon source " refers to the compound of elemental silicon or silicon, and they can provide dopant material under corresponding process conditions and/or promote that filler is motlten metal infiltration.

In the method implementing the present invention, the dopant material (will explain in more detail below) that aluminum base metal can adulterate additional, and be the precursor of oxidation reaction product, form ingot, sheet, rod, plate or other of this type shape.It is made up of the material of pellet, powder, threadiness material, palpus shape material or other suitable shape, and have filling body or the filler group of a kind of silicon source coating, relative to the oriented of this aluminum base metal, the direction of growth that should make oxidation reaction product will towards this filler and enter this filler.The composition of above-mentioned coating is different from the original composition of this kind of filler, and if during a kind of silicon compound, also can be melt the reduction of molten aluminum base metal, thus promote this oxidation reaction process as a kind of adulterant.It is further believed that, the wellability that filler is base metal also can be improved in this kind of silicon source.Such packed bed, for vapour-phase oxidation agent (such as air) and the growth for oxidation reaction product substrate, is all permeable, developed and thus to penetrate into filler by be allowed oxidation reaction product.As illustrated in those pending application applications aforementioned, dopant material is conducive to the oxidation reaction process of base metal, silicon, silicon dioxide and similar silicon-containing compound to be then effective doped source with aluminum for the system of base metal.According to the embodiment that the present invention preferably goes out, in oxygen-containing atmosphere, it is heated to suitable temperature with a kind of silicon compound, forms a kind of oxide coating that can play dopant material effect.When filler forms this oxide coating, can a kind of oxygen-containing gas as oxidant when, realize in original place or by a pre-burning operation in the process forming ceramic body.Unless otherwise mentioned, " filler " or " packing material " is all used to refer to include the group of filler, bed or preform, and at least part of in these fillers has been applied by silicon source, and they can be combined use with the dehydrogenation filler not being loaded with this kind of coating.

As the situation at carborundum, this kind of filler itself can react and form the silicon compound that a kind of energy is the reduction of molten aluminum base metal.It that case, then this kind of filler has inherently possessed the intrinsic doping characteristic provided for above-mentioned coating, and all the other unchanged or unchanged parts are just played filler effect by oxidation reaction product when permeating.This kind of filler of particularly suitable includes carborundum and silicon nitride.When adopting this kind of filler, when heating in air or in other suitable oxygen-containing gas, a kind of silica dioxide coating or silicate coating will be formed.Whenever necessary, this kind of filler can by a kind of suitable silicon source or siliceous parent coating being coated to and forming on entirely different filler.Such as, a kind of particularly effective system of this kind of type is applied to the tetraethyl orthosilicate on Zirconium oxide fibre, and the latter, when drying or appropriate heating are decomposed, is formed into silica coating.Another example is, can be coated onto on alumina particle by ethyl silicate glass, be formed as silica coating during heating.

According to one embodiment of the invention, carborundum that a kind of suitable filler is granular or silicon nitride etc., at oxygen-containing atmosphere, for instance in air, it is heated to high enough temp so that a big chunk of this kind of granule scribbles silicon dioxide layer.Such as, when making filler with carborundum, ideally pre-burning at a certain temperature between about 1000 DEG C to about 1450 DEG C, and preferably between 1200 to 1350 DEG C.On this kind of filler, the time produced needed for oxide coating then depends on granular size, shape, voidage and can the oxidant that provide utilization etc factor.For carborundum, when granularity is about 250 to 750 orders/inch, suitable burn-in time is about 5 to 40 hours.Another advantage is that of pre-burning, can produce to form issuable thicker coating in required time than substrate.

In another embodiment, this silicon dioxide film or coating are then formed on the spot with oxygen-containing gas for the oxidation reaction process of oxidant.The assembly of aluminum base metal Yu filler is placed in a suitable refractory container, is heated to one and is not only higher than base metal fusing point, and be high enough to be formed the temperature of sufficient silica dioxide coating on filler.In this embodiment, vapour-phase oxidation agent used in the oxidation reaction forming substrate also reacts with filler and is formed as silicon oxide film.Such as, when using silicon carbide filler, and this kind of filler has been aluminum base metal when penetrating into the oxidation reaction product alumina host of oxygen-containing vapour-phase oxidation agent (preferably air), oxide coating will be formed at moderate temperatures on this silicon-carbide particle.First combinations thereof body is heated between 1000 to 1450 DEG C preferably about 1200 to 1350 DEG C to a certain temperature.After silicon dioxide film or coating are formed in silicon carbide filler, it is possible to keep or change this temperature range, so that this oxidation reaction process proceeds to be simultaneously generated this ceramic composite structures.

In the another embodiment of the present invention, it is possible to adopt chemical vapor deposition etc method to carry out filler being coated with silicon.Especially it is fibrous, granular at filler or must shape, it is necessary to protecting its situation not being damaged under corresponding process conditions, the method can be effective especially.Such as, boron nitride particle is accomplished by protecting it to aoxidize and reacting with melted, and silicon coating provides for such protection and can also meet the present invention requirement in other side.

Carborundum and silicon nitride etc filler preferably takes granular form, and can include granularity or grade is different and admixture of preferably about 10 to 1000 orders, but may be used without thinner granule.The raw material of relatively coarse grain but then should be adopted in silicon nitride situation, in case oxidation or react excessive and form aluminium nitride and silicon.Under granular form, it is possible to the filler of this blending is made a kind of filler with required permeability, porosity and density or the like character.

Above-mentioned filler is usually with any suitable bonding material, bonding agent, bonding compound or continuous sticky object, it is combined into a kind of bed body or preform, as long as this kind of sticky object is without influence on the course of reaction of the present invention or remarkable amounts of unbefitting residue by-product under leaving in this Ceramic Composite product.Have found that, it is adaptable to the bonding agent of this kind of purpose such as includes the latex and the like of polyvinyl alcohol, epoxy resin, natural and synthesis, and these are well known in corresponding technique.Above-mentioned filler, no matter wherein there being adhesive-free, can use any traditional method of casting, injection moulding, transfer modling and vacuum forming or the like, so as to by preliminary dimension and shape formable.

Such filler preferably takes preform form, has at least a surface-boundary, and should maintain sufficient shape globality and raw intensity and the fidelity of size in the process of ceramic body with forming process.But, this packed bed or preform also should have enough permeabilitys, with the polycrystalline matrix material that accommodation grows.Such as, it is adaptable to a kind of carborundum of the present invention or silicon nitride preform, the porosity that it has is by volume between about 5 to 90%, and preferably about between 25 to 75%.

In proceeding as described above, one can the filler of pre-burning and/or preforming to put into the part on the one or more surfaces with aluminum or surface adjacent.This filler is preferably made to contact with the immense surface of base metal, if desired, also it can be made partly and to be not fully immersed in motlten metal, because the result of full leaching can end or block vapour-phase oxidation agent enters filler, for making the passage of polycrystalline matrix normal growth.The formation of oxidation reaction product will occur in towards and enters the direction of filler.

The assembly that aluminum by filler with as base metal forms, is placed in the heating furnace of suitable vapour-phase oxidation agent supply, higher than this base metal fusing point but lower than in the temperature range of the fusing point of oxidation reaction product, heat combinations thereof body.When being vapour-phase oxidation agent with air, the temperature range of this process, for aluminum base metal, is between about 700 to 1450 DEG C, and the most suitable be between about 800 to 1350 DEG C.In the temperature range that this operating temperature above-mentioned is interval or the most suitable, define molten metal body or bath of molten metal, when itself and oxidising agent, will react and form one layer of oxidation reaction product.Continuing to be exposed under this oxidation environment, in suitable temperature range, namely the motlten metal of surplus is little by little introduced into towards the direction of oxidant and passes through oxidation reaction product.Reaction, when itself and oxidising agent, is formed additional oxidation reaction product by above-mentioned motlten metal.Have at least this oxidation reaction product of part to remain to contact and be in both molten parent metal and oxidant between both, continued through established oxidation reaction product and to transport towards oxidant by be allowed this motlten metal so that multi-crystal oxidation reacting product penetrates into and is at least in a part of filler.By pre-burning in position, or the silicon source coating carrying out precoated shet and being formed on this filler, by being added to by silicon source doping material continuously in whole filler group, accelerate the growth of multi-crystal oxidation reacting product.

Above procedure proceeds until this kinds of oxidation reaction product at least penetrates in a part of packed bed.If employing preform, then this process will be performed continuously over this oxidation reaction product and penetrate into already and be embedded into this preform and respectively organize in ingredient, until a surface-boundary determined, and require not past this border, not so will result in the what is called of polycrystalline matrix material " undue growth ".

The polycrystalline matrix material of final acquisition should be known it is possible that hole, these holes are perhaps then the results of part or almost substituted metal component fully, and the percent volume of these holes will largely depend on, and temperature, time, base metal be continuous and concentration of dopant so some conditions.Generally, in these polycrystalline ceramic structures, being connected with each other between oxidation reaction product crystallite is not just one-dimensional, and it is more likely that three-dimensional, and metal or hole are likely at least to be part of the interconnected simultaneously.If have employed preform, then the ceramic composite product of final gained will have size and the geometry of original preform, and also have fidelity good especially when have employed barrier layer.

Vapour-phase oxidation agent used in this oxidation reaction process is generally gaseous state, or vaporizable under the process conditions, it provides the oxidizing atmosphere as air.But, when apply pre-burning or after the filler of precoated shet, this kind of oxidant then needs not to be oxygen-containing gas.Typical steam (gas) oxidant, their application depends on that filler is pre-burning or precoated shet possibly, additionally include such as nitrogen or nitrogenous gas, and the mixture of air, H2/H2O and CO/CO2 etc, the oxygen that wherein latter two (i.e. H2/H2O and CO/CO2) can be used to reduce in environment is the activity of required oxidation component relative in preform.The mixture (including air) of oxygen or oxygen-containing gas is suitable vapour-phase oxidation agent, and due to obvious economic cause, air is preferably.When a kind of vapour-phase oxidation agent identified for containing or when including certain specific gas or steam, this refers to this mark gas in a kind of vapour-phase oxidation agent or steam, is the unique, reigning of base metal or is at least a kind of effective oxidant under oxidation environment used.Such as, although key component is nitrogen in air, but oxygen contained in air is then when oxidation environment used, unique oxidant of base metal.Then air is defined as " oxygen-containing gas " oxidant, but " nitrogenous gas " oxidant.The example of here and in detail in the claims used a kind of nitrogenous oxidant is " forming gas ", and it typically contains the hydrogen of the nitrogen of about 96% volume and about 4%.

Under above-mentioned process conditions, the oxidant of a kind of liquid or solid can be combined use with this vapour-phase oxidation agent.This kind of additional oxidant can be particularly helpful to make base metal at the filler internal ratio surface external enwergy preferential oxidation at filler.In other words, adopt this kind of additional oxidant, such a ratio can be founded in filler outside packed bed or preform, be more beneficial for the oxidation kinetics environment of base metal.With regard to silicon carbide filler as preform, the environment that this kind improves contributes to making substrate grow into interface in preform and make undue growth phenomenon cut to bone.

When to vapour-phase oxidation agent certain solid oxidizer of additional employing again, the latter such as granular form mixing with filler can make it be scattered in whole filler group or in only adjacent with base metal partial filler, the employing of any suitable solid oxidizer, depend on the matching of it and vapour-phase oxidation agent, this kind of solid oxidizer includes suitable element, such as boron, or suitable reducible compound, such as some borate, borate glass, and thermodynamic stability is lower than the silicate of base metal and product and silicate glass.

If adopting a kind of liquid oxidizer to vapour-phase oxidation agent is still further outer, as long as then this kind of liquid oxidizer will not hinder this vapour-phase oxidation agent to enter molten parent metal, so that it may so as in being scattered in whole packed bed or be distributed to on motlten metal adjacent portion filler.So-called a kind of liquid oxidizer refers to a kind of oxidant under oxidation reaction condition for liquid, thus a kind of liquid oxidizer can have its solid-state predecessor, for instance salt, it is molten state or liquid under Redox Condition.On the other hand, this kind of liquid oxidizer can be again a kind of liquid predecessor, for instance the solution of a kind of material, this material melts under these process conditions or decomposes, and is formed as applicable a part of oxidant.Defined herein oxidant example includes low-melting glass.

If adopting a kind of preform shaped, this kind of preform just should have fully many holes or can with saturating property so that vapour-phase oxidation agent can be penetrated into preform and contact with molten parent metal.This kind of preform also should have sufficiently high permeability to allow that oxidation reaction product grows within the border of preform, and essentially without disturbance, destruction or change its configuration or geometry.When this preform include a kind of can with the solid oxidizer of vapour-phase oxidation agent and/or liquid oxidizer time, at this moment, the porosity of this preform or permeability even as big as allowing and to accept, and plant the growth of the oxidation reaction product of solid oxidizer and/or liquid oxidizer since then.

The present invention provides a kind of compounded mix in one embodiment, when it is heated to proper temperature in oxygen-containing atmosphere, it is provided that a kind of intrinsic source of dopant material, for instance, namely it is a kind of intrinsic source of the silicon dioxide as adulterant as the carborundum of filler.In certain applications it may be necessary to or wish to adopt a kind of additional dopant material to supplement that adulterant originally provided for silicon source.If additionally using one or more adulterant except silicon source, then they: (1) can supply as the alloy compositions of base metal；(2) can be applied at least some of surface of this kind of base metal；Or (3) can be applied to or be incorporated in all or part of filler；Or can use with any two in (3) or multiple method in conjunction with (1), (2).Such as, a kind of adulterant for base metal alloying can be used alone, or is used in conjunction with in conjunction with the adulterant related silicon compound coating again that the second is additional.It is applied in the method (3) of filler at one or more adulterant having adnexa, it is possible to complete this kind of operation according to any appropriate ways illustrated in those pending applications aforementioned.Many factors rather than dopant material itself are depended in the effect of a kind of dopant material.This kind of factor such as includes: when have employed two or more adulterants, their concrete combining form；Apply a kind of additional adulterant to combine with by a kind of adulterant of base metal alloying；The concentration of adulterant and process conditions.

With the adulterant for aluminum base metal that combines with silicon source, when especially with air for oxidant, these adulterants include magnesium and zinc, as described below, and they can be combined use with other adulterant.Both metals or their suitable source, it is possible to be alloyed in aluminium base base metal by following condition, the concentration of each of which is by the metal gross weight gauge being finally doping to, between about 0.1 to 10%.If desired, silicon metal can with this base metal alloying, to supplement the silicon source of the coating being used as on filler.In this kind of example, comparatively ideal magnesium density, by weight in the scope of about 0.1 to 3%, is the scope about 1 to 10% by weight for silicon, and for zinc, if be combined use with magnesium, by weight then in the scope of about 1 to 6%.This kind of dopant material or their suitable source (such as MgO and ZnO) can be used on base metal from the outside.Such as, for the aluminum base metal being oxidant with air, using Mg O is as adulterant, and its quantity is approximately more than 0.0008 gram in base metal every gram to be oxidized, and MgO amount in base metal surface is approximately more than 0.003g/cm2, aluminium oxide ceramics component thus can be made.

Can help to the example of other dopant materials that aluminum base metal reacts with oxygen-containing atmosphere and include sodium, germanium, stannum, lead, lithium, calcium, boron, phosphorus and yttrium, condition according to oxidant and corresponding technique, they can by oneself or be combined use with one or more other adulterant.The rare earth element of cerium, lanthanum, praseodymium, neodymium etc is also all useful adulterant, and is here mainly combined use with other adulterant.Except the coating of silicon source, all dopant materials illustrated in aforementioned pending application application, for aluminium base base metal system, the growth of multi-crystal oxidation reacting product can be promoted.

It is usually a kind of bonding product by implementing the ceramic composite product of gained of the present invention, according to the entire volume of this product, wherein contains about 5% to 98% and embedded in a kind of polycrystalline ceramics matrix fill.This polycrystalline ceramics substrate is when with air or oxygen for oxidant, by volume (volume of polycrystalline ceramics) meter, include the interconnective alpha-aluminium oxide of about 60% to 99%, by weight (same conversion basis) count about 1% to 40% metal component, such as, not oxidation component in base metal, or the metal reduced from adulterant or oxidant.

As proposing on May 8th, 1986 and transferring in the pending U.S. Patent application No861024 of same assignee disclosed, a kind of barrier layer can be combined use and grows with inhibited oxidation product or run off this barrier layer with filler.Can be any meet the material of following requirement, compound, element, mixture or the like as this applicable barrier layer, they can keep globality to a certain degree under the process conditions of the present invention, non-volatile, and preferably can be suppressed again, retrain, stop, disturb, stop or block in other forms simultaneously the continued growth of oxidation reaction product locally for vapour-phase oxidation agent is permeated.Calcium sulfate (Gypsum Fibrosum preparata), calcium silicates, ordinary cement and their mixture, be particularly well-suited to the situation with aluminum for base metal and oxygen-containing gas oxidant, is usually and is coated on the surface of filler with a kind of slurry or paste forms.A kind of suitable combustibility that can eliminate when may also include heating in more such barrier layers or volatile material, or include decomposable material during a kind of heating, in order to improve the porosity on barrier layer and permeable rate.Additionally, a kind of suitable fire-resistant bulk goods also can be contained in this kind of barrier layer, to reduce any contingent contraction or cracking in technical process.This kind of refractory matter grain, specially requires its coefficient of expansion substantially identical with packed bed.For example it is assumed that the salic and final ceramic body of preform also includes aluminium oxide, then barrier layer available alumina granule blending now, granularity is advisable with about 20 to 1000.

Following several examples are used for explaining the practical operation of some aspect of the present invention.

Example 1 is made for a kind of ceramic component according to the method for the present invention, oxidation reaction product including a kind of aluminium oxide, it is embedded between the β-SiC whisker by the supply of Nikkei technical research company, the latter is coated with commercially available cabosil (LudoxHS-30 at the beginning, E.I.Du Pont Company supplies) or sodium silicate solution (40～42 Baume degrees), as the supplementary source of silicon.Being mixed with a kind of liquid medium respectively by β-SiC whisker batch of material three parts independent, the slurry of gained is injected in a mould, then degasification drying in vacuum desiccator, being made for three diameters is 2 inches, the preform of former 3/8 inch.This kind is mixed with the liquid medium of β-SiC whisker and includes for the distilled water regulated, colloidal silica sodium silicate solution.These three preform is placed on the El corundum (supply of trade name Alundum, Norton company) of 90 grades being contained in a fire-resistant boat.Some aluminium alloy ingots (No7122) that diameter is identical with above-mentioned preform scribble the silica sand of thin layer in its side, make the coat side of each alloy pig contact with the upper face of a preform.Above-mentioned such assembly is inserted in heating furnace in 5 hours, is warming up to 900 DEG C.Keep 36 hours at this temperature, then this assembly was cooled to ambient temperature in 5 hours.Containing only in the preform (regulating with distilled water) having β-SiC whisker, it is possible to ignore the infiltration of aluminium oxide oxidation reaction product.β-SiC the whisker being coated with cabosil is then infiltrated on the whole thickness of preform.The infiltration of β-SiC whisker body is to occur at the immediate vicinity of preform by sodium silicate solution.

Example 2 is made for a kind of ceramic composite component according to the method for the present invention, oxidation reaction product including the aluminium oxide of a kind of granule that embedded in silicon carbide filler, (39Crystolon*, 500 grades, Norton company supplies), filler particles scribbles cabosil (LudoxHS-30, u E.I.Du Pont Company supplies, 30% solution) as silicon source time initial.The mixture deposition of two parts of carborundum pellets (500 grade) with a cabosil liquid is poured in a rubber mold, it is made for being of a size of in two preforms of 2 × 2 × 1/2 inch, on carborundum and pellet, so defines the coating of cabosil.Shaping with dried, one of these two preforms are pulverized, make 100% ground all over crossing 100 orders.Then adopt the binding agent (Elmer rubber, Berden company supplies) of 2% propylene vinegar latex, make the above-mentioned carborundum scribbling cabosil again deposit cast.Only with emulsion binder prepare one identical with these preforms above-mentioned.The preform of the unused colloidal silica silicon coating of carborundum therein.

By three aluminium alloys 712, (name composition is Si .15% by weight；Mg .6%；Zn, 6%) rod, is placed on the resistance to grate that wollastonite fibre element (NYADFP, Petty-Rowley chemical company) being contained in fire-resistant boat forms, the face making one 2 × 2 (inch) of each rod is exposed in air, and substantially concordant with this bed surface.Now by aforesaid three preforms, each is seated on the end face of this kind of alloy bar, makes each corresponding preform be directed at on 2 × 2 (inch) face of both alloys.The top of these preforms is distributed one layer of wollastonite fibre, in order to slow down ceramic substrate undue growth to the border running off preform.Such assembly is inserted in heating furnace, was heated to 1000 DEG C through 10 hours.Allow this heating furnace keep 80 hours at 1000 DEG C, be then cooled to ambient temperature through 10 hours.From stove, take out this assembly, reclaim this ceramic composite component ultimately formed.With these final composite material elements of slight blasting treatment to remove the material being not embedded into preform.It will be clear that the preform applying silica dioxide coating granule is substantially embedded to its space boundary place in these pictures, the preform including silicon dioxide is then substantially rarely ceramic substrate infiltration.

Example 3 is made for a kind of ceramic composite component, the dry oxidation reaction product including a kind of aluminium oxide of the universe, the boron nitride pellet being embedded into silicon coating according to the method for the present invention.

By one according to alloy 380.1 (Belmont metal company is supplied, nominally the composition demarcated is Si by weight, 8～8.5%；Zn, 2～3%；As the Mg of activated dopants, 0.1%；And Cu and the Fe of 3.5%, Mn and Ni, but wherein the content of Mg sometimes higher to 0.17 to 0.18% scope) be buried in the bed of boron nitride pellet (about 50 order granularity).These boron nitride particles scribble silicon layer (using chemical vapor deposition method coating), in case boron nitride is degraded and plays the effect of silicon doped source, supplement the silicon source in alloy.Boron nitride particle bed is contained on a fire-resistant boat.This assembly is inserted in a heating furnace, and stove has for by the opening of air, through heating in 5 hours to 1100 DEG C.This stove is allowed to keep 48 hours in 1100 DEG C and to be cooled to ambient temperature.Take off this final ceramic composites.

Three above example shows, with the filler in the silicon source with intrinsic doping character, can effectively be used for promoting the formation of composite material element.Although only detailing several exemplary embodiments of the present invention above, but the people being familiar with this technique will quickly recognize that the present invention includes various version except given example.

Claims (10)

1. the method preparing self-supporting ceramic composite, this species complex is suitable as maybe can be processed as article of commerce and include: a kind of ceramic substrate that (1) is formed polycrystalline material by a kind of aluminum base metal of oxidation and obtains, this kind of polycrystalline material mainly comprises the oxidation reaction product of (a) above-mentioned base metal and the oxidant including vapour-phase oxidation agent and (b) selectively one or more metal component；(2) a kind of filler penetrated into for described substrate；The method includes: (A) takes the relative direction that surely above-mentioned aluminum base metal is mutual with filler, make being formed of this kinds of oxidation reaction product will occur on the direction of this filler, in this kind of filler, at least part of filler is loaded with a kind of silicon source coating, the composition in this silicon source is different from the original composition of this filler, and the silicon source addressed has the doping character of intrinsic；(B) above-mentioned aluminum base metal is heated to one higher than its fusing point but lower than the temperature of this oxidation reaction product fusing point, to form a kind of melted aluminum base metal, simultaneously, namely this molten aluminum base metal reacts at the temperature disclosed above with described oxidant and forms this oxidation reaction product, and allow at this temperature and be at least a part of this oxidation reaction product and this molten metal body and this oxidising agent and between this therebetween, migrate towards above-mentioned oxidant with filler direction increasingly by this oxidation reaction product with this motlten metal, so that this oxidation reaction product continues to be formed on this filler inner oxidizing agent and established oxidation reaction product interface therebetween；(C) continue one period of sufficient time of above-mentioned reaction, make polycrystalline material penetrate at least some of filler.

2. this method as claimed in claim 1, wherein described silicon source is that one can by aforementioned melt base metal silicon compound of reduction in step (B) with (C).

3. this method as claimed in claim 1, the silicon source coating wherein addressed is the oxidation by a kind of silicon parent or dissociates and formed.

4. this method as claimed in claim 3, wherein address form the oxidation of this kind of silicon source coating or dissociation be the directed operation in aforementioned (A) before carry out.

5. this method as claimed in claim 3, wherein addresses the oxidation forming this kind of silicon source coating or dissociation, is carry out in original position in forming the process that described oxidation reaction produces.

6. this method as in any of the one of claim 3,4 or 5, wherein addresses the described oxidation reaction forming this coating, is form silica dioxide coating when oxygen-containing atmosphere by heating aforementioned silicon source.

7. the method according to claim 1,2,3,4 or 5 any one, the filler wherein addressed is to choose from the compound group that carborundum, silicon nitride, aluminium oxide, zirconium oxide and boron nitride are constituted.

8. the method as described in claim 1,2,3,4 or 5 any one, about 700 DEG C to 1450 DEG C scopes of the heating steps heating-up temperature in wherein said (B).

9. the method as described in claim 1,2,3,4 or 5 any one, the wherein said heating steps in (B) is when oxygen-containing atmosphere, carry out to the temperature of 1450 DEG C in about 1000 DEG C, to form above-mentioned silicon source coating, and after this coating is formed in situ on described filler greatly, namely change this temperature to continuously form so-called oxidation reaction product.

10. the method as described in claim 1,2,3,4 or 5 any one, wherein also includes at least one additional dopant material of employing and combines with described base metal.