Abstract: A dense, self-sintered silicon carbide/carbon-graphite composite material and a process for producing the composite material is disclosed. The composite material comprises a silicon carbide matrix, between 2 and 30 percent by weight carbon-graphite, and small amounts of sintering aids such as boron and free carbon. The silicon carbide has an average grain size between 2 and 15 .mu.m, and the carbon-graphite has an average grain size between 10 and 75 .mu.m, the average grain size of the carbon-graphite being greater than the average grain size of the silicon-carbide. The composite material has a density of at least 80 percent of theoretical density as determined by the rule of mixtures for a composite material. This density is achieved with minimal microcracking at a high graphite loading with large graphite particles. The composite material exhibits good lubricity and wear characteristics, resulting in improved tribological performance.

Abstract: A process for producing a carbon-filled ceramic composite material comprising a ceramic matrix and a carbon domain dispersed therein with a carbon domain diameter of from 0.01 to 30 .mu.m and a carbon domain area ratio of from 5 to 70%; comprising the steps of mixing ceramic powder, sintering aids and a carbon source, calcining the mixture at 300.degree.-600.degree. C., granulating the mixture, molding and sintering.

Abstract: The present invention is embodied in a method of producing a ceramic foam. The steps for producing the ceramic foam include first mixing a liquid pre-ceramic resin with a liquid phenolic resin, second allowing the resultant mixture to chemically foam, third curing the mixture for a time and at a temperature sufficiently to convert the mixture to a polymeric foam, and then heating the resultant polymeric foam for a time and at a temperature sufficiently to completely break-down polymers of the polymeric foam and convert the polymeric foam to a ceramic foam.

Abstract: A silicon carbide ceramic body having a high degree of lubricity as a result of large graphite inclusions in the body. The graphite inclusions have an average size of at least about 100 micrometers. The graphite-loaded silicon carbide component is preferably formed by spray drying graphite particles independent of the silicon carbide, blending the graphite agglomerates and silicon carbide to form a raw batch, forming the raw batch into a green body, and sintering the green body to produce a graphite-loaded silicon carbide ceramic body having good density and good strength.

Abstract: Silicon carbide sintered bodies having controlled porosity in the range of about 2 to 12 vol %. in which the pores are generally spherical and about 50 to 500 microns in diameter, are prepared from raw batches containing a polymer fugitive. Sintered bodies in the form of mechanical seal members exhibit lower power consumption at low PV and, in addition, lower wear rates at high PV in comparison to commercially available silicon carbide seal members.

Abstract: The invention relates to a process or producing components of silicon carbide with addition of carbon and/or carbon-containing binders, in which the carbon is obtained at least in part by pyrolysis of the binders in the green component. The binder used is, according to the invention, modified starch preferably with a sulfamate or a sulfonic ester which is dispersible and/or soluble and/or dissolved in water.

Abstract: The invention discloses a long carbon fibre reinforced ceramic matrix composite in which the matrix is an engineering ceramic, characterized in that the engineering ceramic comprises Al.sub.2 O.sub.3 and Y.sub.2 O.sub.3 as highly refractory sinter additives, the composite has a high density of at least 95% theoretical, a high fibre content of at least 30% by volume, and that substantially all the fibres are uniformly distributed within the matrix with a uniform inter-fibre spacing of 10-15 micrometer. The invention also discloses a process for preparing such a composite, characterized in that unidirectionally wound fibre tapes are cut into sections, the sections are infiltrated by the matrix material in the form of a slurry of the ceramic itself or as a precursor material, the infiltrated fibre tape sections are successively stacked and pressed wet to achieve intermeshing of the tape sections, compacted, dried and hot pressed.

Abstract: Mechanically strong and reduced friction porous silicon carbide sintered shaped articles, well adapted for the production, e.g., of leaktight mechanical packings and rotating bearing seals, have a total pore volume ranging from 4% to 18% thereof, the pores of which having an average diameter ranging from 40 to 200 .mu.m.

Abstract: Silicon carbide sintered bodies having controlled porosity in the range of about 2 to 12 vol %. in which the pores are generally spherical and about 50 to 500 microns in diameter, are prepared from raw batches containing a polymer fugitive. Sintered bodies in the form of mechanical seal members exhibit lower power consumption at low PV and, in addition, lower wear rates at high PV in comparison to commercially available silicon carbide seal members.

Abstract: A porous membrane produced by preparing a slurry made from at least one micropyretic substance and at least one liquid carrier. The slurry is dried into a green form having a desired geometric configuration. Combustion of the green form produces the porous membrane.

Abstract: A self-sintered silicon carbide/carbon-graphite composite material having interconnected pores which may be impregnated, and a raw batch and process for producing the composite material, is provided. The composite material comprises a densified, self-sintered matrix of silicon carbide, carbon-graphite inclusions and small amounts of any residual sintering aids, such as boron and free carbon, and has interconnected pores which may be impregnated with resin, carbon, TEFLON, metal or other compounds or materials selected for their particular properties to achieve desired tribological characteristics for a specific application. The composite material is produced from a raw batch which includes silicon carbide, sintering aids, a temporary filler and coated graphite particles. The raw batch is then molded/shaped into a green body and heated to carbonize any carbonizable materials and to decompose and volatilize the organic filler to form a matrix of interconnected pores.

Abstract: The subject-matter of the present invention is to solve the technical problem resulting from the instability in air of polysilanes. For this purpose, it proposes a polysilane-based composition, used particularly for producing silicon carbide, comprising:polysilane chains capable of being degraded by oxidation and the formation of polysiloxane-type products and/or polysilane chains suitable for being bound together directly by a reaction between Si--H and Si--X radicals, and/or indirectly through the intermediary of a crosslinking additive and by a reaction between A--X and A--H radicals, X being an olefin radical, preferably comprising 1 to 18 carbon atoms and, more preferably still, being constituted by a vinyl radical (Vi:--CH.dbd.CH.sub.2), A being an organic, organosilicic or silicic radical;and at least one antioxidant system.

Abstract: A composite is comprised of reinforcement fibers having a continuous coating with a first layer of a metal oxide wherein the metal is from the group consisting of aluminum, yttrium, titanium, zirconium, beryllium, silicon, and the rare earths, and a molten silicon infiltration formed silicon carbide matrix. The coating may have a second layer from the group consisting of rhodium, iridium, metal carbide, metal silicide, metal nitride, and metal diboride, on the metal oxide coating. The reinforcement fibers being fibers from the group consisting of elemental carbon, silicon carbide, and mixtures thereof. A process for producing the fiber reinforced composite comprises depositing on the fibers a continuous coating comprised of the first layer of the metal oxide, and the second layer. A carbonaceous material is admixed with the coated fibers so that at least 5 volume percent of the mixture is the fibers.

Abstract: A silicon carbide ceramic body having a high degree of lubricity as a result of large graphite inclusions in the body. The graphite inclusions have an average size of at least about 100 micrometers. The graphite-loaded silicon carbide component is preferably formed by spray drying graphite particles independent of the silicon carbide, blending the graphite agglomerates and silicon carbide to form a raw batch, forming the raw batch into a green body, and sintering the green body to produce a graphite-loaded silicon carbide ceramic body having good density and good strength.

Abstract: This invention relates to a composite of silicon carbide and carbon. This invention also relates to its manufacturing method. An obtained composite is used as heat resistant, wear resistant or chemical resistant materials. The object of this manufacturing method is to form a deep layer of silicon carbide and carbon in the surface of a carbon base by a simple process of causing a silicon containing material to penetrate into and react with the carbon block. Further object of this invention is to produce a compound in whole comprised of silicon carbide and carbon if the carbon block is 20 mm or below in thickness. To this end, according to this forming method a carbon block having a lattice constant c of 6.708 .ANG. to 6.900 .ANG. or below and a density of 1.3 g/cm.sup.3 to 1.7 g/cm.sup.

Abstract: The present invention generally relates to mechanisms for preventing undesirable oxidation (i.e., oxidation protection mechanisms) of reinforcement materials in composite bodies. The oxidation protection mechanisms include getterer materials which are added to the composite body which gather or scavenge undesirable oxidants which may enter the composite body. The getterer materials may be placed into at least a portion of the matrix such that any desirable oxidant approaching, for example, a fiber reinforcement, would be scavenged by (e.g., reacted with) the getterer. Ceramic filler materials which serve as reinforcements may have a plurality of super-imposed coatings thereon, at least one of which coatings may function as a getterer. The coated materials may be useful as reinforcing materials in ceramic matrix composites to provide improved mechanical properties such as fracture toughness.

Abstract: A rapid process for the preparation of diamond articles in which a porous, dense preform of diamond particles created by particle packing methods is subjected to forced flow chemical vapor infiltration of a carbon containing reagent gas resulting in the preparation of thick diamond articles.

Abstract: Disclosed are high density, sintered titanium carbide bodies comprising 2-10 wt % silicon carbide, up to 2 wt % free carbon and 88 to 98 wt % titanium carbide.

Abstract: A silicon carbide ceramic body having a high degree of lubricity as a result of large graphite inclusions in the body. The graphite inclusions have an average size of at least about 100 micrometers. The graphite-loaded silicon carbide component is preferably formed by spray drying graphite particles independent of the silicon carbide, blending the graphite agglomerates and silicon carbide to form a raw batch, forming the raw batch into a green body, and sintering the green body to produce a graphite-loaded silicon carbide ceramic body having good density and good strength.

Abstract: Pressureless sintering is used to densify silicon carbide based ceramics using a compound comprising transition metal oxides and aluminum oxide at temperatures in excess of 1850.degree. C. The resulting sintered body has a density greater than 95% of its theoretical density, flexural strength in excess of 560 MPa and fracture toughness of 7.2 MPa.m.sup.1/2. The method consists of sintering and conversion of transition metal oxides into carbides in one step operation. Practically any transition metal oxide can be used. The sintered ceramic bodies made by the present invention consist of silicon carbide matrix phase and Al.sub.2 O.sub.3 and transition metal carbide phases.

Abstract: Silicon carbide sintered bodies having controlled porosity in the range of about 3-25 vol % are prepared from raw batches containing a multimodal distribution of silicon carbide particles and comprised of at least a first set of particles having one average grain size and a second set of particles having another average grain size larger than the first set of particles. The resulting pores are 3-5 microns in the largest dimension, with an aspect ratio between about 1/1 and about 3/1 . The porous bodies, e.g., in the form of mechanical seal members, exhibit good tribological properties.

Abstract: A dense, self-sintered silicon carbide/carbon-graphite composite material and a process for producing the composite material is disclosed. The composite material comprises a silicon carbide matrix, between 2 and 30 percent by weight carbon-graphite, and small amounts of sintering aids such as boron and free carbon. The silicon carbide has an average grain size between 2 and 15 .mu.m, and the carbon-graphite has an average grain size between 10 and 75 .mu.m, the average grain size of the carbon-graphite being greater than the average grain size of the silicon carbide. The composite material has a density of at least 80 percent of theoretical density as determined by the rule of mixtures for a composite material. This density is achieved with minimal microcracking at a high graphite loading with large graphite particles. The composite material exhibits good lubricity and wear characteristics, resulting in improved tribological performance.

Abstract: The present invention discloses a composition for a valve of an advanced heat engine. The valve comprises grains of aluminum-doped silicon carbide. The grains are of two main types: (1) a matrix of equi-axed grains of alpha and beta SiC for optimum distribution of mechanical properties; and (2) elongated grains of alpha SiC which are distributed within the matrix for reinforcement. The invention also comprises a process for making such valves. The process begins with a powder of aluminum-doped beta-silicon carbide. A binder and a solvent are then added to the powder, and the mixture is agitated while being heated. The mixture is then transferred to an injection mold which is used to form a molded component. The molded component is then sintered and machined into desired dimensions. An annealing step is then performed so that the component exhibits the characteristics of improved strength and toughness.

Abstract: Silicon carbide sintered bodies having controlled porosity in the range of about 2 to 12 vol %. in which the pores are generally spherical and about 50 to 500 microns in diameter, are prepared from raw batches containing a polymer fugitive. Sintered bodies in the form of mechanical seal members exhibit lower power consumption at low PV and, in addition, lower wear rates at high PV in comparison to commercially available silicon carbide seal members.

Abstract: Ceramic precursor materials bound together by a product of a condensation reaction between a first reactant that has at least one reactive hydroxyl moiety, such as a carbohydrate, and a second reactant that has at least one reactive nitrogen-containing moiety, such as melamine, and dried or dried and calcined, form porous aggregates that resist crushing or disintegration during processing through various reactor apparatus.

Abstract: Carbon fiber reinforced silicon nitride based nanocomposite material is produced by mixing a powder mixture of silicon nitride powders (with or without alumina powders), and fine silicon carbide powders, with a solution of a preceramic polymer containing silicon and nitrogen, to form a solution for impregnation, by passing carbon fibers through the solution to produce a mass of impregnated carbon fibers, forming the mass to a desired shape and by sintering in an inert atmosphere. Ultra-high strength and toughness are produced due to reinforcement by nanocompositization of the matrix phase, that by dispersion of fine particles and that by long carbon fibers, part of matrix phase is generated by thermal cracking of preceramic polymer.

Abstract: A new silicon carbide material is made following a procedure including hot pressing to provide a finished product having a microstructure with an optimal grain size of less than 7 micrometers. The material exhibits a dominant failure mode of intergranular fracture requiring significant energy for crack propagation. The method of manufacturing is cost-effective by allowing the use of "dirty" raw materials since the process causes impurities to segregate at multi-grain boundary junctions to form isolated pockets of impurities which do not affect the structural integrity of the material. End uses include use as protective projectile-resistant armor.

Abstract: A new silicon carbide material is made following a procedure including hot pressing to provide a finished product having a microstructure with an optimal grain size of less than 7 micrometers. The material exhibits a dominant failure mode of intergranular fracture requiring significant energy for crack propagation. The method of manufacturing is cost-effective by allowing the use of "dirty" raw materials since the process causes impurities to segregate at multi-grain boundary junctions to form isolated pockets of impurities which do not affect the structural integrity of the material. End uses include use as optical and electronic substrate materials.

Abstract: The preparation of porous ceramic bodies by sintering certain curable organopolysiloxanes filled with silicon carbide powders. This process is advantageous in that the green bodies have relative high strengths and thus can be easily handled and, if desired, machined before sintering.

Abstract: Improved gunnable plastic refractory compositions consist of a mass of friable clusters of granular material which has a moisture content of from about 4% to about 10% by weight of the total composition and contains from about 0.05% to about 0.5% by weight (added), preferably 0.1% to 0.3%, of a hydrocolloid selected from the class consisting of a polysaccharide ether and xanthan gum and from about 0.05% to about 1.0% by weight (added), preferably 0.15% to about 0.50%, carbon.

Abstract: A silicon-carbide sintered article prepared by permeating molten silicon into a carbon compact of elemental carbon, wherein Lc(002), which indicates a length of a domain in the direction perpendicular to the C(002) surface of elemental carbon in the carbon compact, is up to 1000 angstrom. The resulting article includes silicon carbide, silicon, and up to about 1 percent by weight of residual elemental carbon based on the sum of the silicon carbide and the silicon.

Abstract: Proposed is a novel composite material consisting of carbon as the matrix phase and particles of silicon carbide having an acicular or needle-like particle configuration uniformly and isotropically dispersed in the matrix phase as the reinforcing dispersed phase, in which the needle-like silicon carbide particles are formed by the in situ crystal growth from particles of .beta.-silicon carbide in a shaped body of a powder blend consisting of particles of carbon and the powder of .beta.-silicon carbide with further admixture of boron or a boron compound which promotes crystal growth of silicon carbide to have an acicular particle configuration.

Abstract: For silicizing porous moldings of silicon carbide/carbon, a mixture of silicon carbide powder, organic binder and, if appropriate, carbon is molded to give a green compact, the binder of the green compact is removed by carbonization at about 1000.degree. C. in a non-oxidizing atmosphere and the resulting blank is silicized by the action of molten silicon, while the resulting blank rests on a porous SiSiC carrier, whose lower part is in contact with the molten silicon. The carrier used may be a close packing of porous SiSiC rings which are arranged mutually parallel and perpendicularly on a graphite firing plate which is charged with silicon and is impermeable to molten silicon; or the carrier may be plane having a plurality of recess; or the carrier may have a straight channel with an angular cross section and recesses, into which the blank to be silicized is placed, wherein the SiSiC carrier has downward protruding side walls, whose undersides are in contact with the molten silicon.

Abstract: A low cost pressureless sintered silicon carbide ceramic composite having relatively high electrical conductivity, relatively high density and relatively great mechanical strength, in comparison to those known to persons skilled in the art, and a process for making such composites.

Abstract: A new silicon carbide material is made following a procedure including hot pressing to provide a finished product having a microstructure with an optimal grain size of less than 7 micrometers. The material exhibits a dominant failure mode of intergranular fracture requiring significant energy for crack propagation. The method of manufacturing is cost-effective by allowing the use of "dirty" raw materials since the process causes impurities to segregate at multi-grain boundary junctions to form isolated pockets of impurities which do not affect the structural integrity of the material. End uses include use as optical and electronic substrate materials.

Abstract: A binder-containing granulated silicon carbide products for the manufacture of highly dense silicon carbide ceramic products and the SiC ceramic products which can be made from the novel granulated silicon carbide products, especially highly dense SiC high-performance pressurelessly sintered ceramics.

Abstract: A fiber-reinforced ceramic composite material reinforced by particle dispersion with improved fracture toughness comprised of a mullite matrix, and fibers and same or different kind of ceramic fine particles both dispersed within the mullite matrix is produced by a method comprising: dispersing mullite particles forming a matrix in a solution dissolving an organometallic macromolecular substance to prepare an impregnating solution, continuously passing fibers through said impregnating solution to uniformly impregnate the fibers with said impregnating solution, laminating said fibers to provide a laminated body, converting the organometallic macromolecular substance within said laminated body into a nonmeltable state, and performing sintering (or press sintering) of said laminated body in an inert gas and/or nitrogen gas. By press sintering K.sub.Ic of 10 MN/m.sup.3/2 or more is achieved.

Abstract: A coated carbon body having improved resistance to high temperature oxidation and a method for producing the coated carbon body are described. The coated carbon body comprises a carbon body, an intermediate glass forming coating and an outer refractory coating on the intermediate coating. The body has a converted porous layer formed by etching and reacting the body with boron oxide and the resulting converted layer contains interconnecting interstices and boron carbide formed by the reaction of the boron oxide and the carbon body. The method comprises contacting a carbon body with boron oxide at an elevated temperature sufficient to cause the reaction between the carbon body and boron oxide to form a converted porous layer which contains interconnecting interstices in the body and boron carbide and then applying the glass forming coating over the converted layer. Preferably an outer refractory coating is applied over the glass forming coating.

Abstract: The preparation of porous ceramic bodies by sintering certain curable organopolysiloxanes filled with silicon carbide powders. This process is advantageous in that the green bodies have relative high strengths and thus can be easily handled and, if desired, machined before sintering.

Abstract: This invention relates to an improved pack mixture composition useful for the formation of a SiC pack cementation coating for protecting a carbonaceous substrate from degradation at temperatures above about 800.degree. F. comprising: Si from about 15% to about 50% by weight of the total composition; B up to about 25% by weight of the total composition when present; SiO.sub.2 from about 0.01% to about 3% by weight of the total composition; and SiC from about 40% to about 85% by weight of the total composition.The invention also relates to a method for protecting a carbonaceous substrate from degradation at temperatures above about 800.degree. F. comprising: preparing a pack mixture composition of from about 15% to about 50% Si, up to about 25% B, from about 0.01% to about 3% SiO.sub.

Abstract: A SiC ceramic sintered body containing 0.05-5 atom % Sc, 10 atom % or less free carbon, 2 atom % or less oxygen, balance SiC, is described where 75% or more of the Sc is dissolved into the SiC grains.

Abstract: This invention relates generally to a reaction which occurs on the surface of a substrate body. Particularly, at least one solid oxidant is contacted with at least one parent metal to result in a reaction therebetween and the formation of a reaction product on the surface of a substrate body.

Abstract: The invention is related to a heat treatment method for silicon and carbon-containing ceramic fibers as well as fibers of the same nature with a laminated structure and having an external carbon layer.The processing method for the invention comprises a heat treatment in vacuum, during at least three hours and at a temperature of about 1000.degree. C. This treatment yields fibers surrounded with a layer of endogenic SiO.sub.2, that is itself coated with a layer of endogenic carbon.Said fibers can be used to make composite materials with fiber reinforcement.

Abstract: The present invention concerns novel high strength ceramic fibers derived from boron, silicon, and carbon organic precursor polymers. The ceramic fibers are thermally stable at and above 1200.degree. C. in air. The method for preparation of the boron-silicon-carbon fibers from a low oxygen content organosilicon boron precursor polymers of the general formula Si(R.sub.2)BR.sup.1 by melt-spinning, crosslinking and pyrolysis. Specifically, the crosslinked (or cured) precursor organic polymer fibers do not melt or deform during pyrolysis to form the silicon-boron-carbon ceramic fiber. These novel silicon-boron-carbon ceramic fibers are useful in high temperature applications because they retain tensile and other properties up to 1200.degree. C., from 1200.degree. to 1300.degree. C., and in some cases higher than 1300.degree. C.

Abstract: A diamond tool which generates little vibrations, can be used in high temperature environments and can be produced with excellent yield has at least a shank portion (2) in contact with a diamond chip (1) and formed from a reaction-sintered silicon carbide material having a thermal expansion coefficient close to that of the diamond chip by using a diamond granule, and a method for producing the diamond tool which comprises contacting a diamond chip with an ingredient layer mixed with a diamond granule and a carbonaceous source, placing a metallic silicon powder on the surface of the layer, and then reaction-sintering it in vacuum or in a non-oxidizing atmosphere by heating, thereby forming a reaction-sintered silicon carbide material having a coefficient of thermal expansion close to that of a diamond chip, at least, in the shank portion at which a diamond chip is in contact.

Abstract: Silicon carbide-coated carbonaceous substrates are overcoated with one or more ceramic layers derived from an organoborosilazane polymer solution containing 0-60% by weight of dispersed ceramic or preceramic powdered solids to seal the silicon carbide coating and provide better resistance to oxidative deterioration at elevated temperatures; the organoborosilazane polymer being the product obtained by reacting about 0.25-20 parts by weight of a trialkoxy-, triaryloxy-, or tri(arylalkoxy)boroxine with one part by weight of a polysilazane in an organic solvent. The thus-coated substrates are optionally overcoated with a buffer layer and then with one or more ceramic layers derived from polysilazane solutions or dispersions.

Abstract: A method of infiltration forming silicon carbide bodies having an improved surface finish comprises, infiltrating a porous carbonaceous preform with molten infiltrant to form a silicon carbide body. The body is heated in an inert atmosphere or vacuum to a temperature where the infiltrant is molten while the body is positioned in contact with an infiltrant wicking means. Preferably, the wicking means has infiltrant wicking capillaries at least as large as the infiltrant wicking capillaries in the body. Capillary force draws excess infiltrant on the surface of the body from the surface leaving the reaction formed silicon carbide body with a surface substantially free of excess infiltrant droplets.

Abstract: A ceramic fiber-ceramic composite filter having a support composed of ceramic fibers, preferably texturized, a carbonaceous layer thereover, and a silicon carbide coating over the carbonaceous layer and coated on substantially all of the fibers. A strong, tough, light weight filter is achieved which is especially useful in high temperature gas environments.

Abstract: A high-density and high-strength .beta.-type silicon carbide sintered body, in which crystal grains are made uniform and fine by adjusting the compounding ratio of the sintering aid and further taking a special means at the sintering step while suppressing the inclusion of .alpha.-SiC into the starting powder as far as possible during the production of the silicon carbide sintered body.

Abstract: A process for producing high density SiC sintered bodies by primarily firing and then hot isostatic pressing. The process includes the steps of formulating a powder consisting essentially of 90.0 to 99.8% by weight of the SiC powder, boron or a boron-containing compound in an amount of 0.1 to 5.0% by weight when calculated as boron, and carbon or a carbon-producing organic compound in an amount of 0.1 to 5.0% by weight when calculated as carbon, mixing and shaping the formulated powder, firing the shaped bodies in a temperature range from 1,900.degree. to 2,300.degree. C. in vacuum or in an inert gas atmosphere, and then hot isostatically pressing the fired bodies in a temperature range from 1,800.degree. to 2,200.degree. C. under a pressure of not less than 100 atms in an inert gas atmosphere. The SiC powder is an SiC mixed powder consisting essentially of 95.0 to 99.