Abstract: A process for densifying porous articles comprises providing a non-reactive container with a green article and sufficient solid encapsulating agent selected from the group consisting of tin and the tin-magnesium eutectic to encapsulate the green article when the agent is in the molten state. The temperature is raised sufficiently to melt the agent and to encapsulate the article. The encapsulated article is maintained at a pressure below the infiltrating pressure of the green article while heating the encapsulated article sufficiently to create a surface on the article that is essentially free of porosity and thereafter, the pressure on the encapsulated article is increased while maintaining the article at its sintering temperature for a sufficient time to increase the density of said article to at least about 98% of theoretical.

Abstract: Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

Abstract: A sintered hard metal body having improved heat resistance and higher cutting performance is produced by a process including mixing together at least one hard substance, at least one binder material, and at least one of at least one complex carbide and at least one complex nitride to form a starting mixture each constituent of which is in powdered form. The at least one hard substance is selected from the group consisting of carbides, nitrides, and carbonitrides of transition metals of Groups IVB, VB and VIB of the Periodic Table of Elements, is present as at least one of a carbide, a mixed carbide, a nitride, a mixed nitride, a carbonitride, and a mixed carbonitride, and has a cubic crystal form. The at least one binder metal is selected from the group including iron, nickel and cobalt.

Abstract: A process for preparing ceramic-metal composites without melting the metal is disclosed. A compact or green body is made from a ceramic and a metal, and the compact is sealed in a vacuum in a container such as a glass envelope. The compact is then heated to a temperature below the melting point of the metal, but high enough so that the vapor pressure of the metal is significant, and the metal redistributes through the ceramic by evaporation and condensation. The composite thereby forms a body having ceramic particles uniformly coated by the metal. Products formed by the process and fabrication of a B.sub.4 C/Cr composite are also disclosed.

Abstract: A magnesium-based composite material having improved mechanical strength, and in particular an improved modulus of elasticity, and a relatively low density. The material is provided by pressing and sintering a mixture of magnesium or magnesium-based alloy particles or a particulate combination of magnesium particles and particles of one or more additional metals, with a reinforcement additive of boron, or boron-coated B.sub.4 C, Si.sub.3 N.sub.4, SiC, Al.sub.2 O.sub.3 or MgO particles.

Abstract: The mould of this invention is intended for the manufacture of small dimensioned parts, in particular those dimensioned on the order of 0.1 mm or less. It comprises one or several mould shells each of which is obtained by:machining a matrix (100) from a hard material of which at least a portion (104) will have the form of a negative of the desired shell, such portion having dimensions slightly greater than those of the shell to be finally obtained;positioning the matrix within a cavity (106) and obtaining a blank of the shell (116) by injecting a mixture composed of a metallic powder and a binding agent into the cavity;eliminating the binding agent by heating the blank and thereafter subjecting said blank to a sintering operation.

Abstract: An improved ceramic-metal composite comprising a mixture of a ceramic material with a ductile intermetallic alloy, preferably Ni.sub.3 Al.

Abstract: A wear-resistant sintered alloy comprising an Cr-C-Fe base alloy in which 0.5 to 3% by weight of CaF.sub.2 and 5 to 20% by weight of hard particles having particle size of 44 to 150 .mu.m and a mean value of Vickers hardness of 800 to 2000 are dispersed. This wear-resistant sintered alloy is produced by a method comprising the steps of adding 1.2 to 2% by weight of carbon powder, 0.5 to 3% by weight of calcium fluoride powder, and 5 to 20% by weight of hard metal powder having the particle size of 44 to 150 .mu.m and a mean value of Vickers hardness of 800 to 2000, to an Fe-Cr-C base alloy powder containing 10 to 20% by weight of Cr and 0.8 to 1.5% by weight of C, mixing them, molding the resultant mixed powder into a desired shaped, and then sintering the compact in the temperature range of from 1180.degree. to 1260.degree. C. in a non-oxidizing atmosphere. The sintered alloy is useful as a material for parts required to have the heat resistance and wear resistance.

Abstract: The present invention relates to a novel method of manufacturing a composite body, such as a ZrB.sub.2 -ZrC-Zr composite body, by utilizing a carburization technique. Moreover, the invention relates to novel products made according to the process. The novel process modifies the residual parent metal which remains in a composite body, by exposing said residual metal to a carburizing environment. Thus, by modifying the composition of residual parent metal, the properties of the resultant composite body can also be modified. Parent metals such as zirconium, titanium, and hafnium are well suited to be treated by the carburizing process according to the present invention.

Abstract: A heat-resistant composite body comprising a composite body of silicon carbide and metallic silicon, the metallic silicon existing in the porous silicon carbide sintered body. The silicon carbide particles constituting the silicon carbide sintered carbide sintered body have an average particle diameter of 5 .mu.m or less, and at least a part of the silicon carbide particles is present in the sintered body in the form of porous secondary particles bonded together. The interconnected pores comprise (i) a group of fine pores having a pore diameter of 3 .mu.m or less, constituted of fine crystalline silicon carbide particles having an average diameter of 5 .mu.m or less and (ii) a group of relatively coarse pores having a pore diameter of from 15 to 40 .mu.m, constituted of porous secondary particles which are bonded to have an average particle diameter of from 40 .mu.m to 150 .mu.m and have a particle size distribution such that 60% by weight or more of particles are included in .+-.

Abstract: A coated cemented carbide alloy having jointly a high toughness and high wear resistance is produced by specifying the cooling rate during sintering in efficient manner, which alloy comprises a cemented carbide substrate consisting of a hard phase of at least one member selected from the group consisting of carbides, nitrides and carbonitrides of Group IVa, Va and VIa metals of Periodic Table and a binder phase consisting of at least one member selected from the iron group metals, and a monolayer or multilayer, provided thereon, consisting of at least one member selected from the group consisting of carbides, nitrides, oxides and borides of Group IVa, Va and VIa metals of Periodic Table, solid solutions thereof and aluminum oxide, in which the hardness of the cemented carbide substrate in the range of 2 to 5 .mu.m from the interface between the coating layer and substrate is 800 to 1300 kg/mm.sup.

Abstract: A process of hot pressing of materials to form articles or compacts is characterized by the steps: (A) providing a compactable particulate mixture; (B) uniaxially pressing the particles without heating to provide article or compact (22); (C) placing at least one article or compact (22) in an open pan (31) having an insertable frame (32) with edge surfaces (34) that are not significantly pressure deformable, where the inside side surfaces of the frame are parallel to the central axis B--B of the open pan, and where each article or compact is surrounded by fine particles of a separating material; (D) evacuating air from the container and sealing the articles or compacts inside the container by means of top lid (36); (E) hot pressing the compacts at a pressure from 352.5 kg/cm.sup.2 to 3,172 kg/cm.sup.

Abstract: A process for the production of a secondary powder composition having a nanocrystalline structure and being comprised of binary or quasi-binary substances composed of at least one of the elements Y, Ti, Zr, Hf, Nb, Mo, Ta and W and at least one of the elements V, Cr, Mn, Fe, Co, Ni, Cu and Pd, optionally also containing further ingredients, such as Si, Ge, B and/or oxides, nitrides, borides, carbides, and their possible mixed crystals. The components are in powdered form and are mixed in elementary form or as pre-alloys and have particle sizes ranging from 2 to 250 .mu.m. The powder components are subjected to high mechanical forces in order to produce secondary powders having a nanocrystalline structure. The secondary powders obtained in this way can be processed into molded bodies according to known compression molding processes, but at a temperature below the recrystallization temperature.

Abstract: A method is provided for producing an erosion-resistant layer or coating on the surface of a metallic workpiece. The method includes providing a thermally sprayable alloy of Ni-Cr-Fe-B-Si and thermally spraying the alloy on the workpiece to a specified thickness, following which the sprayed-on layer is heated in vacuum to a temperature between 250.degree. C. to 400.degree. C. for a time at the stated temperature of about 5 to 30 minutes sufficient to effect degassing of the layer. The temperature of the layer is thereafter raised to a range of about 800.degree. C. to 950.degree. C. and maintained at that temperature in vacuum for between 5 to 30 minutes. The temperature at the layer is then raised to between 900.degree. C. and 1100.degree. C. under a protctive atmoshpere at a pressure of between 200 to 600 mm Hg to effect fursion of the layer at above its melting point, following which the coated metallic workpiece is finally cooled to room temperature under the protective atmosphere.

Abstract: The present invention relates to a method of sintering ceramics and ceramics obtained by said method. According to the present invention, the synthesis and sintering of ceramics can be simultaneously carried out by utilizing the reaction heat generated when at least one metallic element selected from metallic elements of IIIb, IVa, Vb and VIb groups of the Periodic Table is combined with at least one nonmetallic element such as B, C, N and Si without heat or by preliminarily heating the ceramics at temperatures remarkably lower than the usual sintering temperature ceramics, thus-produced are superior in abrasion resistance and corrosion resistance.

Abstract: Disclosed is a roller for use in a rotary compressor, which roller comprising a sintered body consisting essentially of 0.5-2.0% by weight of C, 1.0-5.0% by weight of Cu, 1.2-3.0% by weight of Mo and a balance of Fe and unavoidable impurities. In the sintered alloy, hard particles of Fe-Mo alloy are dispersed in one of pearlitic and tempering martensitic matrix, and sintered pores of the sintered body is sealed with tri-iron tetroxide. Resultant sintered body has high wear resistance and scuffing resistance capable of being used as an inverter type compressor.

Abstract: A pellet for fabricating a metal matrix composite is made of a mixture of a matrix member of a metal powder and at least one reinforcement selected from whiskers, short fibers and suitable particles, the reinforcement being uniformly distributed in a matrix of the metal powder and said mixture being kept in a shape with a binder, wherein said pellet has a surface layer of dried and rigid portion of said mixture which is rigid enough to keep its shape under an external pressure applied thereto. The pellet is formed from a flat cake of the mixture separated from a slurry consisting of a solution medium and the mixture dispersed therein uniformly. Alternatively, the pellet is formed from the mixture in a dried condition with a granulation binder diluted with a solution medium.

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: 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: Self-supporting bodies are produced by reactive infiltration of a parent metal into a boron donor material and a carbon 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: Methods are disclosed of making and of using a high density high strength titanium diboride comprising material. The method of making comprises (a) compacting a mixture of titanium diboride, 5-20% by weight of a metal group binder, and up to 1% oxygen and up to 2% graphite, the mixture having a maximum particle size of 5 microns, and (b) sintering the compact to substantially full density. The TiB.sub.2 may be replaced by up to 10% TiC. The method of use is as a cutting tool at relatively high speeds against aluminum based materials.

Abstract: An alloy tool of hard metal has a working part and a non-working part. The working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase and an iron family metal as a basis metal of the binder phase. The working part includes a region for working a work piece. The non-working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase of the non-working part and of an iron family metal as a basis metal of the binder phase of the non-working part. A diffused junction between the working and non-working parts bonds the two parts together.

Abstract: A softer metal such as aluminum, or a metal forming a metal aluminide, or an alloy containing these metals is added to a metal aluminide composite during fabrication to promote easy consolidation of the metal aluminide matrix with the reinforcing phase. The metal aluminide may be titanium aluminide, nickel aluminide, or iron aluminide. The softer metal, the metal aluminide matrix, and the reinforcing phase are pressed together at a temperature above the softening temperature of the softer metal. The softened metal promotes flow and consolidation of the matrix and the reinforcement at relatively low temperatures. The composite is held at an elevated temperature to diffuse and convert the soft metal phase into the metal aluminide matrix. By consolidating at a lower temperature, cracking tendencies due to thermal expansion differences between the matrix and reinforcement is reduced. By consolidating at a lower pressure, mechanical damage to the fibers is avoided.

Abstract: Spiral parts, such as orbiting and fixed scroll plates having involute wraps, for use in scroll compressors, the parts having low coefficient of thermal expansion and high tensile strength and Young's modulus, are formed by combining a self-lubricating power into aluminum raw material powder prior to compression and forging. As an alternative to and in conjunction with the foregoing, temperatures during preform heating and in the die for forging are controlled to be in respective ranges of 300.degree. to 500.degree. C. and 150.degree. to 500.degree. C. Aluminum alloy fine powder preferably has a particle diameter no larger than 350 .mu.m. The self-lubricating powder preferably forms 1 to 25% of the mix by volume, and contains at least one member selected from the group consisting of graphite, BN, and MoS.sub.2.

Abstract: A process is described for making a composite article without shrinkage, particularly of ceramic and metal wherein the article includes complex internal surfaces or cavities. The process requires forming an insert body that includes an external surface that corresponds to an internal cavity of the article. The insert body consists of a material having a melting temperature less than that of the article. The process further requires forming a porous compact about the insert body wherein the compact is formed into the substantially the net shape of the article. The compact is made of a material that is wetted by liquid insert material and has a sintering temperature greater than the wetting temperature of the insert material. The process further requires heating the article to a temperature such that the inserts substantially melts and infiltrates the porous compact forming the finished composite article.

Abstract: A method for producing PLZT generally expressed as (Pb.sub.1-x La.sub.x) (Zr.sub.1-y Ti.sub.y).sub.1-x/4 O.sub.3 (0<x.ltoreq.0.3, 0.ltoreq.y.ltoreq.1.0) comprises the steps of forming a coprecipitated body by reacting solution containing at least one of Pb, La and Ti with a zirconium-containing solution and a precipitation-forming solution, or (a) forming a solution containing at least one of Pb, La and Ti forming PLZT generally expressed as (Pb.sub.1-x La.sub.x) (Zr.sub.1-y Ti.sub.y).sub.1-x/4 O.sub.3 (0<x.ltoreq.0.3, 0.ltoreq.y.ltoreq.1.0) and a zirconium-containing solution and carrying out a hydrolysis reaction to produce a sol body, (b) drying and then presintering the coprecipitated body at a temperature of from 700.degree. to 1300.degree. C. to form a modified zirconia powder, (c) mixing the presintered body with a compound having a remaining component composition of a required PLZT composition, (d) presintering the mixture at a temperature of from 500.degree. to 1000.degree. C.

Abstract: Discloses hot working by rolling or forging of mechanically alloyed aluminum-base alloys containing 5 to 35 volume percent of an aluminum transition metal intermetallic phase, e.g. Al.sub.3 Ti which is insoluble in the solid aluminum matrix. Hot working is carried out at a temperature above about 370.degree. C.

Abstract: A wear resistant slide member made of iron-base sintered alloy in which carbides are dispersed in a matrix phase. 80% or more of the carbides contained in an alloy metallurgical structure are 4.about.15 .mu.m in sized, the carbides are dispersed at an average grain interval of 5.about.15 .mu.m, and a field-of-view occupation area proportion of the carbides is 10.about.15%. If this slide member is used in slide contact with a second slide member made of iron-base alloy whose slide surface layer is subjected to remelt-hardening treatment by means of high-density energy irradiation, amounts of abrasion of the both slide members are sufficiently small, and excellent durability as a combination of slide members for use in a power machine, can be revealed.

Abstract: A sintered metal part which has a pressed and sintered core; the part is coated with a sintered metal surface layer; the layer has a property different from that of the metal part; the interior regions of the core are free of the metal constituting the coating; and process for making the parts.

Abstract: Amorphous metal-ceramic and microcrystalline metal-ceramic composites are synthesized by solid state reaction-formation methods. These metal-ceramic composites are characterized by a composition that ranges from about 75 to about 99.9 percent ceramic in about 0.1 to about 25 percent amorphous or microcrystalline metal binder phase.

Abstract: An aluminum matrix composite containing evenly dispersed reinforcement particles in the aluminum matrix wherein the contents of oxygen and carbon are controlled so that their volume percentage is not larger than 20% and wherein the contents of the reinforcement particles, oxygen and carbon are controlled so that their volume percentage is not larger than 40%. The control of oxygen and carbon is effected by carrying out the main process at a non-oxidizing atmosphere and minimizing the addition of an anti-seizure agent required to facilitate the mechanical alloying treatment.

Abstract: This invention relates to metal matrix composites containing at least 40% v/v of a hard material such as SiC and a matrix of aluminium, magnesium or alloys of either. The invention also covers a method of making such composites by ball milling powders of the respective components. Other mixing techniques do not enable such a high proportion of hard material to be incorporated into the composite. The composites are useful to produce components resistant to wear.

Abstract: An abrasive material comprised of a metal matrix and evenly distributed ceramic particulates, is made by mixing powder metal with the ceramic powder and heating to a temperature sufficient to melt most, but not all of the powder. In this way the ceramic does not float to the top of the material, yet a dense material is obtained. A nickel superalloy matrix will have at least some remnants of the original powder metal structure, typically some equiaxed grains, along with a fine dendritic structure, thereby imparting desirable high temperature strength when the abrasive material is applied to the tips of blades of gas turbine engines. Preferred matrices have a relatively wide liquidus-solidus temperature range, contain a melting point depressant, and a reactive metal to promote adhesion to the ceramic.

Abstract: Sputter targets and a process for producing sputter targets are provided, comprised of carbides and/or nitrides and/or borides of refractory metals. In a first step, a dense composite body is produced comprised of one or more carbides and/or nitrides and/or borides of the metals of Groups IV A-VI A of the periodic table and a metallic binding agent comprised of one or more metals of the iron group of the periodic table. This composite body in the form of a shaped blank is machined, if necessary, and the binding agent is removed by chemical or electrochemical treatment. The sputter target as so produced has excellent mechanical strength and high thermal shock resistance. Levels of contaminating elements and the residual metallic binding agent are extremely low, meeting the requirements typically placed on sputter targets.

Abstract: A microcomposite material having a matrix of a titanium-base alloy, the material further including about 10-80% by weight TiC substantially uniformly dispersed in the matrix. Several methods of cladding a macrocomposite structure including pressing quantities of a matrix material and a microcomposite material composed of the matrix material and a compatible stiffener material into layers to form a multi-layered compact and sintering the multi-layered compact to form an integral metallurgical bond between the layers of the compact with diffusion but essentially no composition gradient between the layers. A multi-layered macrocomposite article composed of an alloy layer of a matrix material and a layer of a microcomposite material composed of the matrix material and a compatible stiffener material bonded together at the interface region between the layers, the interface region being essentially free of a composition gradient.

Abstract: A method of producing a metal/ceramic composite structure in which an uncolidated metal or metal alloy powder is loaded into a sealable glass mold comprising a hollow ceramic sleeve and a sealable outer glass envelope surrounding the ceramic sleeve and forming with the outer wall of the ceramic sleeve a sealable chamber for the metal or metal alloy powder, wherein the glass is a type which becomes plastic when heated. The air in the mold is removed under vacuum and the mold is sealed and placed into a free flowing refractory powder in a crucible and consolidated by sintering under atmospheric pressure (CAP.RTM. process). Removal of the glass envelope leaves a composite article having a consolidated metal or metal alloy layer surrounding and placing a hollow ceramic liner (sleeve) under both radial and axial compression. A ceramic-line metal gun barrel insert can be produced by using a ceramic sleeve with rifling on its inner surface.

Abstract: Disclosed herein is a metal-ceramic composite article which includes a metallic member made of a precipitation hardenable alloy and a ceramic member, wherein a projection of the ceramic member is fitted into a hole or a through hole formed in the metallic member and the metallic member of the composite article is hardened through precipitation hardening. A process for manufacturing such a metal-ceramic composite article is also disclosed. The manufacturing process includes the steps of: fitting a projection formed at a ceramic member into a hole formed in the metallic member made of a precipitation hardenable alloy in a state in which precipitation-hardening is not carried out to form a metal-ceramic joint body, and subjecting the thus formed metal-ceramic composite body to a precipitation hardening treatment to harden the metallic member.

Abstract: A metal-ceramic composite article produced by fitting a projection formed on a ceramic member into a hole formed in a metallic member having a hardened region and an unhardened region on its surface such that the ceramic member is monolithically bonded to the metallic member and the deformed region of the metallic member resulting from the fitting is located within its unhardened range, has a high bonding force between the ceramic member and the metallic member and is adapted to be used in engine parts, such as turbocharger rotor, gas turbine rotor and the like, and other structural parts exposed to high temperature or to repeating loads, by utilizing the heat resistance, wear resistance and high strength of the ceramic.

Abstract: A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

Abstract: The present invention is directed to a cermet material comprising a matrix of metal or alloy with ceramic particles distributed therein. The cermet includes a glass binder for bonding between the metal or alloy and the ceramic particles.

Abstract: A process is disclosed for producing composite agglomerates of molybdenum and molybdenum carbide (Mo.sub.2 C). The process involves forming a relatively uniform mixture of non-agglomerated molybdenum powder and carbon powder having a particle size of no greater than the particle size of the molybdenum powder. The amount of carbon powder is proportional to the amount of molybdenum carbide desired in the composite agglomerate. A slurry is formed of the mixture, an organic binder, and water with the amount of the binder being no greater than about 2% by weight of the mixture; and the powders are agglomerated from the slurry. The agglomerated powders are then classified to remove the major portion of the agglomerates having a size greater than about 170 mesh and less than about 325 mesh from the balance of the agglomerates. The balance of the agglomerates in which the particle size is -170 +325 mesh is then reacted at a temperature of no greater than about 1400.degree. C.

Abstract: A solid particle erosion resistant coating includes angular titanium carbide particles uniformly dispersed through a high chromium iron matrix. In one form, the aggregate comprises, by weight, about 30-50% TiC, about 10-30% Cr, about 1.5-5% C and the balance essentially iron in the form of ferrite. The matrix also includes metallurgically identifiable amounts of high chromium content M.sub.7 C.sub.3 carbides therethrough. The coating does not exhibit austenitic or martensitic structure therethrough. A powder alloy consolidated body also includes a surface adjacent region having a similar TiC and high chromium iron matrix. Further, a method for obtaining the coating includes heating above the austenitization temperature of the matrix alloy and below the melting temperature of iron, and cooling the aggregate so as to attain iron in the form of ferrite in the matrix.

Abstract: Method for the production of a wear resistant part of a soil working tool comprising forming a mixture of 67-90% by volume of iron particles consisting of at least 97% Fe and 10-33% by volume of hard particles having a desired particle size distribution, and subsequently pressing the mixture at a pressure of at least 3500 kp/cm.sup.2 to form a compact, sintering the compact at a temperature of 900.degree.-1200.degree. C., and optionally sinter forging the sintered compact. The sintered part consists of an iron matrix in which hard particles with a predetermined particle size distribution are embedded.

Abstract: Low-density composites are produced consisting chiefly of boron carbide and aluminum, or aluminum alloy, and minor amounts of ceramic material. The method allows control of the rate of reaction between boron carbide and metal so that the final components of the composite, and hence the mechanical properties, are controlled. The invention includes modification of the carbon content of the boron carbide composition, dispersion of boron carbide and formation of a compact, infiltration of the compact by aluminum or aluminum alloy, and heat treatments. The invention produces low-density boron carbide-aluminum composites with a homogeneous microstructure possessing desired mechanical properties.

Abstract: The invention relates to a method for connecting reaction sintered silicon carbide parts to iron and other metal parts of importance is that the connection involves the use of a binder comprising a mixture of silicon and a metal and preferrably it is a eutectic mixture.

Abstract: A method is disclosed for manufacturing a reaction sintered composite article which comprises at least one ceramic component. The method comprises preparing a particulate mixture of precursor powders leading to the formation of said composite material upon reaction sintering, pressing said particulate mixture to a self-sustaining body, heating said body up to a temperature below the temperature at which the reaction sintering is initiated, comminuting the heat treating body, selecting particles of a suitable grain size distribution, pressing said particles into shapes of desired size and configuration, and heating said shapes up to a temperature at which the reaction sintering is initiated. The reaction sintered body comprises borides, carbides, nitrides or silicides of a transition metal of the groups IVb, Vb or VIb of the periodic table (comprising titanium, hafnium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten), and a metal oxide.

Abstract: A novel contact electrode material for vacuum interrupters is disclosed, by which the chopping current value inherent in contact material can be reduced so that it is possible to stably interrupt small lagging current due to inductive loads without generating surge voltages. The material is equivalent or superior to the conventional Cu-0.5Bi material in large current interrupting capability and dielectric strength. The material consists essentially of copper, chromium, iron or molybdenum and chromium carbide or molybdenum carbide. The metallographical microstructure is such that copper is infiltrated into a porous matrix formed by mutually bonding chromium powder, iron or molybdenum powder and metal carbide powder in diffusion state.

Abstract: A three step process in which a metal alloy selected from a tungsten based alloy and molybdenum based alloys is provided to prevent the decarbonization of the alloys. The process involves a three step sintering process wherein the atmosphere during the initial heating step is a mixture of carbon monoxide and hydrogen, thereafter at a intermediate temperature range the atmosphere is hydrogen and a final heating step at a elevated temperature is employed and the atmosphere is a mixture of inert gas and a source of carbon.

Abstract: A process for the production by power metallurgy of a material based on an aluminum alloy, a solid lubricant and at least one ceramic is disclosed. The process is characterized by using a ceramic in powder form with a granulometry of between 1 and 10 .mu.m.This invention finds application in the manufacture of components which are subjected to friction, in particular under hot condition, such as engine liners. These components provide an optimum compromise coefficient of friction and resistance to seizure and wear.

Abstract: A molded, boron carbide-containing, sintered article which includes at least 65 percent by volume boron carbide; and from 5 to 35 percent by volume of at least one binder metal selected from the group consisting of molybdenum, molybdenum alloys, tungsten and tungsten alloys, having a melting point above 1,800.degree. C., and forming no molten borides or carbides within a temperature range of from 1,800.degree. to 1,950.degree. C. A method for producing the article includes the steps of mixing to obtain a homogeneous mixture from 20 to 80 percent by weight boron carbide particles having a particle size ranging from 1 to 1,650 microns with up to 80 percent by weight of particles of the at least one binder metal having a particle size ranging from 35 to 100 microns; introducing the homogeneous mixture into a graphite matrix mold; heating to sinter the homogeneous mixture at a temperature ranging from 1,800.degree. to 2,000.degree. C.