Abstract: The present invention relates to whisker reinforced ceramic bodies with new and improved properties. By replacing the tool pressing with injection molding, surprisingly a more homogeneous structure and more advantageous whisker orientation has been obtained. By choosing the conditions of the molding, it is possible to control the whisker orientation to get optimal material properties. Bodies according to the invention are particularly suitable for chip forming machining of heat resistant materials.

Abstract: In the present invention, there is provided a method for producing a self-supporting ceramic or ceramic composite body by the oxidation of a parent metal to form a polycrystalline ceramic material comprising the oxidation reaction product of said parent metal with an oxidant, including a vapor-phase oxidant, and optionally one or more metallic constituents dispersed throughout the polycrystalline ceramic material. The method comprises the steps of providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body, and heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal. At that temperature, the molten metal is reacted with the oxidant, thus forming the oxidation reaction product.

Abstract: A composite refractory material composition comprises a boron carbide matrix and minor constituents of yttrium-boron-oxygen-carbon phases uniformly distributed throughout the boron carbide matrix.

Abstract: The ceramics of the present invention comprises a composition having a bonding phase constituent component, a dispersed phase constituent component, and unavoidable impurities. The bonding phase constituent component has one or more of titanium and aluminum carbide, nitride and carbonitride compounds including oxygen, and 20% to 48% by volume of decomposed reaction phase cubic crystal boron nitride. The dispersed phase constituent component comprises cubic crystal boron nitride, and the decomposed reaction phase comprises one or more of titanium carbide, titanium nitride and titanium carbonitride, and one or more of aluminum oxide and aluminum nitride, as well as titanium boride. The crystal grain sizes in the bonding phase comprising the decomposed reaction phase, and the crystal grain sizes in the dispersed phase comprising the cubic boron nitride are all substantially less than 1 micron. The titanium and aluminum carbide compound is preferably Ti.sub.

Abstract: The present invention is a process for producing .beta.-sialon based sintered bodies having a fracture toughness (K.sub.IC) of at least 6.5 MPam.sup.1/2.The process comprises preparing a feed that consists of 0.5-20 wt % of a sintering aid (e.g. MgO) with an average particle size of no more than 5.0 .mu.m, 3-40 wt % of an additive (e.g. SiC) with an average particle size of no more than 5.0 .mu.m, with the remainder being a .beta.-sialon powder having an average particle size of no more than 2.0 .mu.m, wet mixing the individual feeds to form a slurry, drying the slurry and sintering the dried slurry.

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: Densified boron carbide-aluminum, ceramic-metal composites that are substantially free of AlB.sub.12, AlB.sub.12 C.sub.2 and Al.sub.4 C.sub.3 result from a two stage process. Admixtures of boron carbide are densified under pressure in stage one, In stage two, the densified admixture is heat treated. In both stages, the temperature is less than 800.degree. C. If the temperatures do not exceed 600.degree. C., the resultant densified cermet has only three phases: a) boron carbide; b) Al.sub.4 BC; and c) aluminum.

Abstract: This invention relates generally to a novel method of manufacturing a composite body, such as a ZrB.sub.2 -ZrC-Zr (optional) composite body, by utilizing a post-treatment process and to the novel products made thereby. More particularly, the invention relates to a method of modifying a composite body comprising one or more boron-containing compounds (e.g., a boride or a boride and a carbide) which has been made by the reactive infiltration of a molten parent metal into a bed or mass containing boron carbide, and optionally one or more inert fillers, to form the body.

Abstract: Self-supporting bodies are produced by reactive infiltration of a parent metal into a boron carbide material which may contain one or both of a boron donor material and a carbon donor material. The reactive infiltration typically results in a composite comprising a boron-containing compound, a carbon-containing compound and residual metal, if desired. The mass to be infiltrated may contain one or more inert fillers admixed with the boron carbide material, boron-containing compound and/or carbon-containing compound. The relative amounts of reactants and process conditions may be altered or controlled to yield a body containing varying volume percents of ceramic, metal, ratios of one ceramic to another and porosity.

Abstract: A cemented carbide of the invention contains at least one of cobalt and nickel; calcium, sulfur, aluminum, silicon and phosphorus; balance tungsten carbide; and unavoidable impurities. The content of cobalt or nickel should range from 4 to 35% by weight. The content of each of calcium, sulfur, aluminum and silicon should be no greater than 50 ppm by weight, while the content of phosphorus should be no greater than 20 ppm by weight. The tungsten carbide has an average crystal grain size of 0.2 to 1.5 micrometers. The cemented carbide may further contain 0.1 to 40% by weight of at least one compound which may be carbides of metals in Groups IVa, Va and VIa of the Periodic Table other than tungsten, nitrides of metals in Groups IVa and Va of the Periodic Table and solid solution of at least two of the carbides and nitrides.

Abstract: A powdered admixture of a boron, carbon, nitrogen or silicon derivative of a first metal is combined with a source of a second metal and, optionally, a source of a third metal or an iron-group metal, subjected to densification conditions (heat and pressure), partially reacted and converted to a hard, wear resistant material. The wear resistant material contains an amount of the first metal derivative as well as a material of varying stoichiometry which is the partial reaction product of components of the powdered admixture. The material may also contain residual, unreacted portions of components other than the first metal derivative. Articles formed from this material can be useful as, for example, nozzles in abrasive or nonabrasive waterjet cutting machines and various parts of wire drawing apparatus.

Abstract: A method for manufacture of Group IVB metal carbide comprising a carbide of a metal selected from the group consisting of titanium, hafnium and zirconium ceramic composites is provided wherein a permeable mass of filler and carbon is contacted with a molten Group IVB metal. The molten metal is maintained in contact with the permeable mass for a sufficient period to infiltrate the permeable mass and to react the molten metal with the carbon source to form a Group IVB metal carbide composite. The permeable mass may comprise a Group IVB metal carbide, or other inert filler, or a combination of filler materials.

Abstract: A powdered admixture of a boron, carbon, nitrogen or silicon derivative of a first metal is combined with a source of a second metal and, optionally, a source of a third metal or an iron-group metal, subjected to densification conditions (heat and pressure), partially reacted and converted to a hard, wear resistant material. The wear resistant material contains an amount of the first metal derivative as well as a material of varying stoichiometry which is the partial reaction product of components of the powdered admixture. The material may also contain residual, unreacted portions of components other than the first metal derivative. Articles formed from this material can be useful as, for example, nozzles in abrasive or nonabrasive waterjet cutting machines and various parts of wire drawing apparatus.

Abstract: A powdered admixture of a boron, carbon, nitrogen or silicon derivative of a first metal is combined with a source of a second metal and, optionally, a source of a third metal or an iron-group metal, subjected to densification conditions (heat and pressure), partially reacted and converted to a hard, wear resistant material. The wear resistant material contains an amount of the first metal derivative as well as a material of varying stoichiometry which is the partial reaction product of components of the powdered admixture The material may also contain residual, unreacted portions of components other than the first metal derivative. Articles formed from this material can be useful as, for example, nozzles in abrasive or nonabrasive waterjet cutting machines and various parts of wire drawing apparatus.

Abstract: A process for preparation of heat-resistant and wear-resistant ceramic material which comprises sintering the material under a non-oxidizing atmosphere until the metal of a component (a) no longer exists as a metallic phase. A starting composition for forming the ceramic material comprises from 1 to 40 wt % of Al.sub.2 O.sub.3, from 0.05 to 8 wt % of sintering assistant, from 3 to 35 wt % total of one or both of ZrO.sub.2 and HfO.sub.2, and from 17 to 95.95 wt % of carbide components (a) and (b), or (a), (b), and (c), wherein component (a) is one or more metals selected from the Groupd IVB, VB, and VIB of the Periodic Table; component (b) is TiC, and component (c) is one or more metal carbides selected from Zr, Hf, and metals of Groups VB and VIB of the Periodic Table.

Abstract: Metal boride powders can be produced with a predetermined particle size by controlling reaction conditions. The metal boride powder is produced by reacting a solid boron source, a metal source and a reductant under conditions sufficient to produce a metal boride powder with a particle size correlating to that of the solid boron source. The reaction is preferably stopped after the formation of products but before any apprecible crystal growth occurs.

Abstract: Substantially dense, void-free ceramic-metal composites are prepared from components characterized by chemical incompatibility and non-wetting behavior. The composites have a final chemistry similar to the starting chemistry and microstructures characterized by ceamic grains similar in size to the starting powder and the presence of metal phase. A method for producing the composites requires forming a homogeneous mixture of ceramic-metal, heating the mixture to a temperature that approximates but is below the temperature at which the metal begins to flow and pressing the mixture at such pressure that compaction and densification of the mixture occurs and an induced temperature spike occurs that exceeds the flowing temperature of the metal such that the mixture is further compacted and densified. The temperature spike and duration thereof remains below that at which significant reaction between metal and ceramic occurs. The method requires pressures of 60-250 kpsi employed at a rate of 5-250 kpsi/second.

Abstract: This invention relates generally to a novel method of manufacturing a composite body, such as a ZrB.sub.2 --ZrC--Zr composite body, by utilizing a post-treatment process and to the novel products made thereby. More particularly, the invention relates to a method of modifying a composite body comprising one or more boron-containing compounds (e.g., a boride or a boride and a carbide) which has been made by the reactive infiltration of a molten parent metal into a bed or mass containing boron carbide, and optionally one or more inert fillers, to form the body.

Abstract: An aqueous plastic composition of an inorganic powder which per se has substantially no plasticity which comprises: the inorganic powder and a polysaccharide of natural origin.The molding and sintering of the plastic composition provide a sintered body of high mechanical strength and dimensional accuracy.

Abstract: The present invention relates to a process for the production of an organoborosilicon preceramic polymer of the structure: ##STR1## wherein R.sup.1 is selected from alkyl having from 1 to 10 carbon atoms or phenyl, and x is selected from 0, 1, 2 or 3;which is pyrolyzable to produce a refractory material comprising inorganic compounds of Si, C and B, which process comprises:contacting a silicon containing compound of the structure:(R.sup.1).sub.x --Si--(CH.dbd.CH.sub.2).sub.4-x or (R.sup.1).sub.x Si--(C.tbd.CH).sub.4-xwith a boron containing compound selected from H.sub.3 B:BH.sub.3, H.sub.3 B:NH.sub.3, BH.sub.3 :N(R.sup.2).sub.3 wherein R.sub.2 is selected from methyl, ethyl, propyl, butyl or phenyl in an inert atmosphere at a temperature of between about 90.degree. and 170.degree. C. for between about 0.1 and 20 hr and recovering the prepolymer. The prepolymer is pyrolyzed to produce a ceramic article useful in high temperature (e.g., aerospace) or extreme environmental applications.

Abstract: This invention relates to the preparation of highly densified ceramic bodies by the pyrolysis of a mixture comprising a preceramic borosiloxane, silicon carbide powder, a curing agent for the borosiloxane, a crosslinking agent for the borosiloxane and, optionally, additional components to facilitate sintering. Such highly densified ceramic bodies can be prepared by sintering under pressure or by a pressureless sintering process.

Abstract: A composition and method for producing boron carbide/titanium diboride composite ceramic powders is disclosed. The process comprises the ordered steps of (a) intimately mixing as reactants boron carbide and a titanium source, such that the average reactant particle size is less than about 20 microns and substantially all discrete reactant areas are less than about 50 microns, and (b) reacting the product of step (a) under conditions sufficient to produce a boron carbide/titanium diboride composite ceramic powder wherein at least a portion of the boron carbide particles form substrates to which at least a portion of the titanium diboride particles are attached. The method can be used to produce a composite ceramic powder having boron carbide and titanium diboride particles less than about 20 microns in diameter.

Abstract: The invention relates to a method of fabrication in the powdered state of ceramic compounds formed between a metalloid and a refractory metal, characterized in that it involves the following steps:a) said metalloid is caused to react with a reducing metal within a liquid bath constituted at least partly by a fused salt of said reducing metal in order to obtain a saltlike intermediate compound which combines said reducing metal and the metalloid, in solution in said bath,b) a reducible salt of said refractory metal is then injected into said bath in a divided form which is directly distributed throughout the bath in order to produce said powder by reaction of the reducible salt with said intermediate compound of the reducing metal.

Abstract: A ceramic-making composition comprising at least one starting powder selected from the group consisting of powders of metals, powders of metal oxides, powders of metal carbides, powders of metal nitrides and powders of metal borides, and a synthetic resin binder. To enhance plastic moldability such as injection moldability and extrusion moldability and facilitate dewaxing, a polyalkylene carbonate is used as the synthetic resin binder.

Abstract: A method for manufacture of Group IVB metal carbide ceramic composites is provided wherein a permeable mass of filler and carbon is contacted with a molten Group IVB metal. The molten metal is maintained in contact with the permeable mass for a sufficient period to infiltrate the permeable mass and to react the molten metal with the carbon source to form a Group IVB metal carbide composite. The permeable mass may comprise a Group IVB metal carbide, or other inert filler, or a combination of filler materials.

Abstract: Disclosed herein is a sintered silicon carbide composite prepared by sintering a blend comprising from 25 to 85% by weight of silicon carbide, from 1 to 25% by weight of at least one of chromium and chromium compound, from 10 to 70% by weight of at least one of carbide, nitride and boride of elements belonging to the groups IVb and Vb of the periodical table, and from 3 to 25% by weight of aluminum oxide, in an inert gas atmosphere at a temperature from 1700.degree. to 2100.degree. C.

Abstract: A process for producing a metal boride sintered body having a density of at least 90% of the theoretical density and a raw material composition therefor. The raw material composition is composed of a metal oxide, a metal carbide, and boron carbide, the amount of boron carbide being 5 to 20% more than the amount stoichiometrically required to form a metal boride by reaction of boron in the boron carbide with the metal element(s) in the metal oxide and metal carbide. By using this composition, it is possible to produce a metal boride sintered body having high density and high hardness without adding a sintering auxiliary or carbon and using a very high pressure.

Abstract: Metal boride powders can be produced with a predetermined particle size by controlling reaction conditions. The metal boride powder is produced by reacting a solid boron source, a metal source and a reductant under conditions sufficient to produce a metal boride powder with a particle size correlating to that of the solid boron source. The reaction is preferably stopped after the formation of products but before any appreciable crystal growth occurs.

Abstract: Reactive ceramic-metal compositions are described that include a ceramic phase of at least 70 percent by volume, 95 percent of theoretical density and a metal phase that retains its chemical reactivity with the ceramic phase after the composition has been fully densified. The composition may be heat treated after densification to form additional ceramic phases in a controllable manner. Preferred ceramic metal compositions wherein the metal and ceramic components retain reactivity after densification include boron carbide ceramic and Al or Mg metals. The process employed in forming said compositions requires first forming a sintered porous body of the ceramic material followed by contacting with the metal component, which may be in chip or solid bar form. The system is then heated to the melting point of the metal and a pressure of at least 200 MPa is employed such that the porous body is filled with metal and the composition is substantially fully densified.

Abstract: A high density metal-boride based ceramic sintered body consists essentially of component (A) at least one of TiB.sub.2, ZrB.sub.2, CrB.sub.2, HfB.sub.2, VB.sub.2, TaB.sub.2, NbB.sub.2, MnB.sub.2, MoB.sub.2, YB.sub.2, AlB.sub.2, MgB.sub.2, CrB, VB, TaB, NbB, MoB, HfB, YB, ZrB, HfB, TiB, MnB, W.sub.2 B.sub.5 and Mo.sub.2 B.sub.5, componet (B) 0.1 wt. %-10 wt. % based on the total amount of a metal binder comprising at least one of cobalt boride, nickel boride and iron boride, and component (C) 0.1 wt. %-10 wt. % based on the total amount of at least one of a double carbide comprising Ti, Zr, W and C, ZrCN, HfCN, or a double carbo-nitride comprising Ti, Zr, Hf and C, N.The sintered body is not easily oxidized and has extremely few pores and high shock resistance even using a fine grain raw material powder because component (C) has an oxygen removing effect during sintering.

Abstract: Ceramic powders selected from the group (a) consisting of ZrB.sub.2, HfB.sub.2, ZfC, ZrN and HfN and ceramic powders selected from the group (b) consisting of TiC, TiN and TiO.sub.2 are mixed, the mixture is sintered in a non-oxidizing atmosphere, a substitution reaction of chemical elements between the compound of the ceramic powders of the group (a) and the compound of the ceramic powders of the group (b) is caused in the sintering, and a ceramic composite substantially comprising compounds which do not belong to the groups (a) and (b) is produced by the substitution reaction. By this process, the affection of the particle size and the aggregation of raw powders to the sintering can be greatly reduced, the ranges of the applicable sintering conditions can be broadened, and dense ceramic composites having fine crystal grains and having excellent mechanical properties can be obtained.

Abstract: A diphasic ceramic compact, sintered without pressure, is prepared for use in a combination of two sliding or sealing elements with improved control of the bearing surface portion of the functional surface; the compact contains44 to 89.5 wt.-% of .alpha.- silicon carbide,0.5 to 6 wt.-% of boron carbide, and10 to 50 wt.-% of metal boridesfrom groups 4b to 6b of the Periodic Table of Elements, and the metal boride content is increased at the functional surface.

Abstract: A method of producing a silicon carbide-based body by infiltrating with molten silicon a porous compact comprising silicon carbide, carbon, and a secondary phase dispersed within the compact. The secondary phase might comprise a titanium compound, or a metal carbide.

Abstract: Self-supporting bodies are produced by reactive infiltration of a parent metal into a boron donor material and a carbon donor material. The reactive infiltration typically results in a composite comprising a boron-containing compound, a carbon-containing compound and residual metal, if desired. The mass to be infiltrated may contain one or more inert fillers admixed with the boron donor material and carbon donor material. The relative amounts of reactants and process conditions may be altered or controlled to yield a body containing varying volume percents of ceramic, metal, ratios of one ceramic to another and porosity.

Abstract: The present invention relates to a novel method of manufacturing a composite body, such as a ZrB.sub.2 --ZrC--Z composite body, by utilizing a post-treatment technique. Moreover, the invention relates to novel products made according to the process. The novel process modifies at least a portion of a composite body by exposing said body to a source of second metal.

Abstract: A powdered admixture of a boron, carbon, nitrogen or silicon derivative of a first metal, e.g., tungsten carbide, and a source of a second metal, e.g., molybdenum subcarbide when the second metal is molybdenum, is, when subjected to densification conditions, partially reacted and converted to a hard, wear resistant material. Such a material, formed from an admixture of tungsten carbide and molybdenum subcarbide, contains tungsten monocarbide and at least one mixed tungsten/molybdenum carbide. This material has a Vickers hardness of at least about 2200 kg/mm.sup.2 measured using a 1 kg load. Articles formed from this material can be useful as, for example, nozzles in abrasive or nonabrasive waterjet cutting machines and various parts of wire drawing apparatus.

Abstract: High surface area, submicron ceramic powders are synthesized by reducing an oxide in the presence of another metal (i.e., Mg, Al, Ca, and the like) and a source of carbon, nitrogen or boron to form a new oxide and a carbide, nitride (or carbonitride). or boride. The oxide phase can be leached out to leave submicron carbides, nitrides or borides. Alternatively milling of reacted powders allows intimate mixtures of uniform, fine grained ceramic powders to be prepared inexpensively. These multiple-phase composite powders can be formed into a body and densified using conventional techniques to form dense, fine-grained ceramic bodies. Alternatively, containment of unreacted powders and subsequent heating results in multiple-phase dense ceramics with unique microstures. Transformation toughening of composites is possible by adding zirconia or hafnia either before or after the powder synthesis step.

Abstract: Production of carbide shapes of silicon, titanium or vanadium by reaction of carbon with the metal in liquid phase such being carried out by heating a mixture of particles of carbon and particles of the metal rapidly to the melting point of the metal, thereby minimizing solid state reaction, and holding at a temperature and for a time sufficient to cause reaction. The metal and carbon particles are about 0.05 to 10 mm in diameter. An organic binder is used which volatilizes or dissociates upon heating.

Abstract: A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Abstract: The present invention relates to a sintered body for chip forming machining containing at least one hard constituent comprising a carbide, nitride and/or carbonitride of a metal of group IVB, VB or VIB in the periodical system and a binder metal based upon Co, No and/or Fe, in which the body comprises a core containing eta-phase or an intermediate phase, substantially free of carbon and/or nitrogen surrounded by a hard constituent- and binder phase-containing surface zone, free of said eta-phase or intermediate phase.

Abstract: A sintered non-oxide ceramic composite high in density, high-temperature strength and toughness and having optionally and widely changeable electrical conductivity is obtained by compacting and sintering a mixed powder comprising 5-95% by weight of at least one compound selected from titanium carbide, nitride and carbonitride, 0.1-5% by weight (based on silicon carbide) of boron or boron compound in terms of boron, 0.1-5% by weight (based on silicon carbide) of carbon or carbon compound in terms of residual carbon and the balance of substantially silicon carbide.

Abstract: In the alumino-thermit method of producing tungsten monocarbide powders, metallic iron is added to the reaction charge in quantities to control the calculated reaction temperature within the range of about 4372.degree. to about 4500.degree. F. It has been found that this process can now be controlled to produce macrocrystalline tungsten carbide powders which are very low in Ti, Ta and Nb content and have a very narrow range of total carbon contents.

Abstract: Preparation of metal carbides, nitrides, borides, silicides and phosphides, also metal alloys and pure metals, by providing a precursor in which there are organic ligands bonded to the metal or metals, such precursor having the element X also bonded directly or indirectly to the metal or metals, the ligand-metal bonding being weaker than the X-metal bonding whereby on pyrolysis the product M.sub.a X.sub.b results in which M represents the metal or metals, X represents C, N, B, Si, P and a and b represent the atomic proportions of M and X. The subscript b may be zero if an alloy or pure metal is to be prepared. The product M.sub.a x.sub.b can be prepared by relatively low temperature pyrolysis and the precursor can be used as a solution or a low melting solid. This enables one to apply a surface coating or to shape the precursor into a fiber, rod or other shape and to pyrolyze the coating or shaped article. M is a transition, lanthanide or actinide metal or tin.

Abstract: The present invention relates to a cemented carbide body, preferably for rock drilling, mineral cutting and wear parts, in which the content of binder phase in the surface is lower and in the center higher than the nominal content. In the center there is a zone having a uniform content of binder phase. The WC grain size is uniform throughout the body.

Abstract: The present invention is characterized by ceramic materials comprising ceramic sintered bodies consisting of (1) 1-90 wt % chromium carbide and the remainder carbonic titanium nitride; (2) 1-90 wt % chromium carbide, 0.1-5 wt % B.sub.4 C and the remainder titanium carbo-nitride; or (3) either of the above compositions plus less than 95 wt % of a metal boride such as Ti or Zr. Such ceramic sintered bodies are used for cutting tools or wear-resistant machine parts because of their high density, high hardness and high strength.

Abstract: The invention relates to a sintered body of a ceramic composite material based on alumina, refractory hard phases and ZrO.sub.2, HfO.sub.2 and/or partially stabilized ZrO.sub.2 with a relative density of more than 98%. The sintered body according to the invention has chromium integrated in amounts corresponding to in all 1-20 weight % and ZrO.sub.2, HfO.sub.2 and/or partially stabilized ZrO.sub.2 present as 2-16 weight % with these latter phases present to more than 70% in the tetragonal crystal modification. Furthermore, the refractory hard constituents are present as particles with a grain size of less than 10 .mu.m and/or as whiskers or fibers with a diameter of less than 5 .mu.m and a length/diameter ratio of >10.

Abstract: The present invention relates to a polyorganoborosilane ceramic precursor polymer comprising a plurality of repeating units of the formula: ##STR1## with the segments being linked together by second units of the formula: --(R.sup.2)--Si--R.sup.3)--q, where R.sup.1 is lower alkyl, cycloalkyl, phenyl, or ##STR2## and R.sup.2 and R.sup.3 are each independently selected from hydrogen, lower alkyl, vinyl, cycloalkyl, or aryl, n is an integer between 1 and 100; p is an integer between 1 and 100; and q is an integer between 1 and 100. These materials are prepared by combining an organoborohalide of the formula R.sup.4 -B-(X.sup.1).sub.2 where R.sup.4 is selected from halogen, lower alkyl, cycloalkyl, or aryl, and an organohalosilane of the formula : R.sup.2 (R.sup.3) Si(X.sup.2).sub.2 where R.sup.2 and R.sup.3 are each independently selected from lower alkyl, cycloalkyl, or aryl, and X.sup.1 and X.sup.

Abstract: A neutron-absorbing material is formed by a process which includes the steps of: mixing an absorptive material having a high thermal neutron capture cross-section (e.g., B.sub.4 C), a neutron-moderating material (e.g., graphite) and a binder (e.g., a phenol formaldehyde resin); shaping such mixture; curing such shaped mixture (e.g., to complete polymerization of the resin and to have only a carbon residue); and siliconizing such shaped and cured mixture. The resulting product has been formed to be denser and stronger, and more oxidation- and abrasion-resistant than prior art compositions.

Abstract: This invention relates to abrasion resistant materials and to articles of manufacture made therefrom. More particularly, it is concerned with abrasion resistant materials comprising boron doped TiC or boron doped VC distributed in a matrix containing silicon nitride and with articles made therefrom.

Abstract: The invention relates to the production of desirably consolidated high purity refractory metal borides, carbides, nitrides, or mixtures, combinations of cermets thereof. In the preparation, a second stage reaction is conducted at reduced pressure and sintering temperature. Furthermore, it is carried out in the presence of sintering aid which can be initially present as a particulate material and, as such, may be incorporated with other reaction ingredients. Sintering aid, in a dual role, may serve not only as an assistant in the second stage reaction, but also as a reaction participant. Moreover, during such rection at sintering conditions, the sintering assistance is obtained by means of sintering aid vapor. High purity products of desirable microstructure can be achieved, having densities on the order of 90 percent or more.