Abstract: High theoretical density, metal-based materials containing graphite or hexagonal boron nitride have low coefficients of friction and wear rates are useful for bearings, bushings and other articles subject to bearing loads.

Abstract: High theoretical density, metal-based materials containing graphite or hexagonal boron nitride have low coefficients of friction and wear rates are useful for bearings, bushings and other articles subject to bearing loads.

Abstract: A transition metal carbide is formed from a precursor mixture comprising at least one of the group consisting of: a transition metal, a transition metal carbide and a transition metal oxide. The precursor mixture may contain the desired transition metal carbide (e.g., WC), but if the desired transition metal carbide is present in the precursor mixture, there is necessarily a significant amount of another compound such as a transition metal oxide, undesired carbide (e.g., W2C) or transition metal.

Abstract: A transition metal carbide-Group VIII metal powder comprising discrete particles of a transition metal carbide and Group VIII metal wherein: substantially all of the particles have a size of at most 0.4 micrometer; the transition metal carbide is selected from carbides of the group consisting of tungsten, titanium, tantalum, molybdenum, zirconium, hafnium, vanadium, niobium, chromium, mixtures and solid solutions thereof; and the Group VIII metal is selected from the group consisting of iron, cobalt, nickel, mixtures and solid solutions thereof. Said powders are produced by heating an admixture comprising a finishing source of carbon (e.g., acetylene black), a source of a group VIII metal (e.g., Co.sub.3 O.sub.

Abstract: A transition metal carbide (e.g., WC) is prepared by the following steps. A carbon-precursor mixture is formed by mixing a precursor comprised of (i) a transition metal oxide (e.g., WO.sub.x) and (ii) a material selected from the group consisting of: a transition metal (e.g., W); a transition metal carbide (e.g., WC) and a substoichiometric carbide (W.sub.2 C), in the presence of a source of carbon (e.g., carbon black) in an amount sufficient to form a reduced mixture comprised of the transition metal carbide and substoichiometric transition metal carbide, wherein the amount of the transition metal oxide and transition metal is essentially zero in said reduced mixture. The carbon-precursor mixture is heated in a reducing atmosphere (e.g., 5 percent hydrogen in argon) to a reducing temperature and for a time sufficient to produce the reduced mixture.

Abstract: A submicrometer transition metal carbonitride is produced having the formula:M.sub.a M'.sub.b M".sub.(1-a-b) (C.sub.1-x) N.sub.x).sub.zwherein M is Ti, Zr or Hf; M' is V, Nb or Ta; M" is Cr, Mo or W; a ranges from 0 to 1; b ranges from 0 to 1 with the proviso that (a +b) is less than or equal to 1; x ranges from about 0.02 to about 0.95 and z ranges from about 0.9 to about 2. The transition metal carbonitride is produced by mixing (a) a transition metal oxide source of a transition metal in the above formula and (b) a carbon source such as carbon black.

Abstract: A transition metal carbide-Group VIII metal powder comprising discrete particles of a transition metal carbide and Group VIII metal wherein: substantially all of the particles have a size of at most 0.4 micrometer; the transition metal carbide is selected from carbides of the group consisting of tungsten, titanium, tantalum, molybdenum, zirconium, hafnium, vanadium, niobium, chromium, mixtures and solid solutions thereof; and the Group VIII metal is selected from the group consisting of iron, cobalt, nickel, mixtures and solid solutions thereof. Said powders are produced by heating an admixture comprising a finishing source of carbon (e.g., acetylene black), a source of a group VIII metal (e.g., Co.sub.3 O.sub.

Abstract: Aluminum nitride powder, aluminum nitride platelets, powdered solid solutions of aluminum nitride and at least one other ceramic material such as silicon carbide, and composites of aluminum nitride and transition metal borides or carbides are prepared by combustion synthesis at low gaseous nitrogen pressures. Porous bodies of aluminum nitride or composites of aluminum nitride and transition metal borides or carbides are also prepared by combustion synthesis at these pressures. The porous bodies are suitable for infiltration, either as formed or after being coated with at least one layer of a silicate material, by polymers or metals. The powders are also suitable for preparing dense sintered bodies. The aluminum nitride powder is also used to prepare AlN sintered bodies.

Abstract: Ceramic-ceramic and ceramic-metal composite materials are disclosed which contain at least two ceramic phases and at least one metallic phase. At least one of these ceramic phases is a metal boride or mixture of metal borides and another of the ceramic phases is a metallic nitride, metallic carbide, or a mixture of metallic nitride and a metallic carbide.

Abstract: A tungsten carbide-containing material in which the tungsten carbide has the general formula, W.sub.x C, wherein x is greater than one and less than two and the material has less than 0.20 weight percent cobalt, a density of at least about 97% of its theoretical density, and a Vickers hardness of at least about 2400 kg/mm.sup.2.

Abstract: Aluminum nitride powder, aluminum nitride platelets, powdered solid solutions of aluminum nitride and at least one other ceramic material such as silicon carbide, and composites of aluminum nitride and transition metal borides or carbides are prepared by combustion synthesis at low gaseous nitrogen pressures. Porous bodies of aluminum nitride or composites of aluminum nitride and transition metal borides or carbides are also prepared by combustion synthesis at these pressures. The porous bodies are suitable for infiltration, either as formed or after being coated with at least one layer of a silicate material, by polymers or metals.

Abstract: Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Abstract: A method of forming a low level carbon high-density tungsten carbide-containing material includes sintering a preform which contains tungsten carbide powder and has a composition such that the resulting sintered material has at most 6.05 weight percent tungsten-bound carbon based on the total weight of tungsten and tungsten-bound carbon. This low level of carbon may be achieved by, prior to the sintering step, oxidizing the tungsten carbide powder sufficiently to achieve the desired substoichiometric carbon level in the sintered product or by adding a carbon-lowering material selected from the group consisting of tungsten, ditungsten carbide, and tungsten oxide. Optionally, other materials can be present in the preform such as carbon-getter metals and compounds thereof. The carbon-getter metals are those metals of which the carbides thereof are more thermodynamically stable than monotungsten carbide.

Abstract: A multi-phase cemented ceramic article, method of making same, and the material thereof is disclosed which is useful for machining and forming of metals, including ferrous metals, titanium, aluminum and other metals. The article and its material preferably includes novel microstructures including platelets, a range of grain sizes which yields superior hardness and other characteristics, and a lower tungsten concentration within the binder phase than has been seen in the prior art. The preferred composition includes ultrafine WC, an ultrafine solid solution of (Ti, Ta, W)C, and a cobalt binder. Platelets are formed in-situ, eliminating the need to add them during manufacture for improving toughness.

Abstract: A method of making metallic carbide powders includes heating a non-static solid reactant mixture of a metal oxide and a source of carbon to a first elevated temperature which is sufficient to cause at least partial carburization of the mixture. The heating is performed in a non-reducing atmosphere having a total pressure of at least one atmosphere for a sufficient time to form a partially-carburized mixture. The source of carbon is employed at a level which is less than the stoichiometric amount needed to produce the metallic carbide. The method may further include admixing a sufficient level of a source of carbon to the partially-carburized mixture to form an adjusted mixture having a total carbon content of the stoichiometric amount needed to make the metallic carbide and carburizing the adjusted mixture in a hydrogen-containing atmosphere at a second elevated temperature which is sufficient to cause the adjusted mixture to form the metallic carbide having a particle size of less than 0.

Abstract: Densified refractory carbide and solid solution carbide materials that have an average grain size of less than 1.1 .mu.m, a density of at least 98% of theoretical may be prepared by any conventional densification procedure. Pressure densified tungsten carbide ceramic materials exhibit a simultaneous increase in Vickers hardness and a toughness (K.sub.IC) with decreasing average grain size.

Abstract: Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

Abstract: Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Abstract: Subject boron carbide to a passivation treatment at a temperature within a range of 1350.degree. C. to less than 1800.degree. C. prior to infiltration with a molten metal such as aluminum. This method allows control of kinetics of metal infiltration and chemical reactions, size of reaction products and connectivity of B.sub.4 C grains and results in cermets having desired mechanical properties.

Abstract: Beta-silicon carbide whiskers of superior uniformity can be formed, either singly or in-situ in a matrix, by heating a source for silicon with a source of carbon (greater than 0 percent but less than or equal to about 60 percent of stoichiometric, with respect to the silicon source) in the presence of a titanium-containing catalyst, such as titanocene dichloride. Advantageously, the titanium catalyst can be applied by drying a solution of the titanium catalyst on the carbon and silicon sources. The titanium, carbon and silicon sources are then heated together, preferably to between about 1800.degree. C. and about 1850.degree. C., resulting in a product containing high quality beta-silicon carbide whiskers.