Abstract: A process for producing a non-dense sintered ceramic molded body having at least two layers, wherein a first powdery ceramic material forming a layer is contacted with at least a second powdery material forming at least a second layer; said first powdery material has a presintering temperature T1 that is higher than the presintering temperature Ts of said at least second powdery ceramic material; the course of a curve of shrinkage S1 of said at least first powdery ceramic material differs from the course of a curve of shrinkage S2 of said at least second powdery material, wherein curve of shrinkage S1 is shifted towards higher temperatures as compared to curve of shrinkage S2; and the layers are subjected to a common temperature treatment at a presintering temperature Ts that is lower than the presintering temperature T1 and at least equal to T3 to cause sintering that remains in a stage of sintering that has not proceeded to the theoretical density; wherein the curve of shrinkage S1 is modified by admixing a

Abstract: Methods of preparing polycrystalline aluminum nitride materials that have high density, high purity, and favorable surface morphology are disclosed. The methods generally comprises pressing aluminum nitride powders to form a slug, sintering the slug to form a sintered, polycrystalline aluminum nitride boule, and optionally shaping the boule and/or polishing at least a portion of the boule to provide a finished substrate. The sintered, polycrystalline aluminum nitride materials beneficially are prepared without the use of any sintering aid or binder, and the formed materials exhibit excellent density, AlN purity, and surface morphology.

Abstract: Methods of preparing polycrystalline aluminum nitride materials that have high density, high purity, and favorable surface morphology are disclosed. The methods generally comprises pressing aluminum nitride powders to form a slug, sintering the slug to form a sintered, polycrystalline aluminum nitride boule, and optionally shaping the boule and/or polishing at least a portion of the boule to provide a finished substrate. The sintered, polycrystalline aluminum nitride materials beneficially are prepared without the use of any sintering aid or binder, and the formed materials exhibit excellent density, AlN purity, and surface morphology.

Abstract: A heater tube is provided for use in a method of producing a diamond or cubic boron nitride (CBN) tipped cutting tool by sintering a mass of crystalline particles to a metal carbide. The heater tube has a cylindrical shape and is comprised of a plurality of windings of an expanded graphite foil which are compressed together. In the method, a heater tube assembly is formed which comprises the metal carbide substrate positioned within the heater tube and a mass of diamond or CBN particles positioned within the heater tube adjacent the substrate. The method includes simultaneously applying sufficient levels of pressure to the heater tube assembly and sufficient levels of electrical current to the heater tube assembly for a sufficient amount of time to cause sintering of the crystalline particles and bonding to the substrate to form a diamond or CBN tipped cutting tool.

Abstract: Disclosed is a method for making a pure aluminum nitride substrate. At first, aluminum nitride is mixed with a water-resistant material and an adhesive material. The mixture is made into grains in a granulation process. The grains are molded into a nugget in a steel mode by hydraulic pressure. The nugget is subjected to a cold isostatic pressing process. At a low temperature, the water-resistant material and the adhesive material are removed from the nugget. Then, the nugget, boron nitride and nitrogen are introduced into and sintered in an oven, thus providing a pure aluminum nitride substrate. The purity and quality of the aluminum nitride substrate are high. The aluminum nitride substrate can be used in a light-emitting diode. The method is simple, the yield is high, and the heat radiation of the aluminum nitride substrate is excellent.

Abstract: [Problems] To provide a method of producing, easily and in a high yield, a reformed aluminum nitride sintered body having very excellent light transmission property which can be favorably used as a light-transmitting cover particularly for light sources having high luminous efficiencies. [Means for Solution] An aluminum nitride sintered body having a concentration of metal impurities excluding aluminum of not more than 150 ppm, an oxygen concentration of not more than 0.5% by weight and a relative density of not less than 95% is used as a starting material. The aluminum nitride sintered body is heat-treated in an oxidizing atmosphere in a temperature region of 1400 to 2000° C. to increase the oxygen concentration by not less than 0.03% by weight.

Abstract: A heater tube is provided for use in a method of producing a diamond or cubic boron nitride (CBN) tipped cutting tool by sintering a mass of crystalline particles to a metal carbide. The heater tube has a cylindrical shape and is comprised of a plurality of windings of an expanded graphite foil which are compressed together. In the method, a heater tube assembly is formed which comprises the metal carbide substrate positioned within the heater tube and a mass of diamond or CBN particles positioned within the heater tube adjacent the substrate. The method includes simultaneously applying sufficient levels of pressure to the heater tube assembly and sufficient levels of electrical current to the heater tube assembly for a sufficient amount of time to cause sintering of the crystalline particles and bonding to the substrate to form a diamond or CBN tipped cutting tool.

Abstract: A deep-grooved ball bearing including a rolling contact member formed of a sintered ?-sialon inexpensive and capable of reliably ensuring sufficient durability includes an outer ring and an inner ring, and a plurality of balls arranged in contact with the outer ring and the inner ring on an annular raceway. The ball is configured of a sintered body that contains as a main component a ?-sialon represented by a compositional formula of Si6-ZAlZOZN8-Z and satisfying 0.1?z?3.5 and has a remainder formed of an impurity.

Abstract: The present invention relates to extrudable ceramic masses and other masses which set as a result of baking or sintering, which masses comprise specific additives based on water-soluble cellulose ethers, an extrusion process, the extrudates and their use.

Abstract: A method for manufacturing an annular nuclear fuel pellet is provided. In the method, an annular nuclear fuel green compact whose lateral cross-section is a trapezoid is prepared. The thickness of the annular nuclear fuel green compact reduces along one direction of the central axis, and a green density of the nuclear fuel green compact increases along one direction of the central axis. The annular nuclear fuel green compact is sintered under a reducing gas atmosphere so that the annular nuclear fuel pellet is obtained. According to this method, the annular pellet which has uniform inner and outer diameters and small diametric tolerances along the pellet height is fabricated without grinding the pellet surfaces.

Abstract: A method is provided for removing a resin layer of a resin-coated metal tube. The resin layer is removed with a laser beam. More particularly, the resin layer of a desired range is burned out by focusing the laser beam into a pinpoint without defocusing the sectional shape of the laser beam in the axial direction o the resin-coated metal tube.

Abstract: The aluminum-nitride-based composite material according to the present invention is an aluminum-nitride-based composite material that is highly pure with the content ratios of transition metals, alkali metals, and boron, respectively as low as 1000 ppm or lower, has AlN and MgO constitutional phases, and additionally contains at least one selected from the group consisting of a rare earth metal oxide, a rare earth metal-aluminum complex oxide, an alkali earth metal-aluminum complex oxide, a rare earth metal oxyfluoride, calcium oxide, and calcium fluoride, wherein the heat conductivity is in the range of 40 to 150 W/mK, the thermal expansion coefficient is in the range of 7.3 to 8.4 ppm/° C., and the volume resistivity is 1×1014 ?·cm or higher.

Abstract: The invention relates to a method of manufacturing nanoscale cubic boron nitride and to the nanoscale cubic boron nitride thus obtained. The method according to the invention of manufacturing nanoscale boron nitride of cubic structure is characterized in that it comprises the following steps: a) compression of a pyrolytic boron nitride powder having a structure of the monomodal turbostratic graphite type at a pressure of between 19 and 21 GPa and at room temperature; and b) heating of the powder under a pressure of between 19 and 21 GPa and at a temperature of between 1447° C. (1720 K) and 1547° C. (1820 K) for less than 2 minutes. The invention is applicable in particular in the field of abrasives.

Abstract: A method of forming a metal deposit on an ultra-hard material. In an embodiment, the method includes providing a plurality of ultra-hard particles, mixing the ultra-hard particles in a solution with a metal salt, drying the solution to create a mixture of metal salt particles adhered to surfaces of the ultra-hard particles, heating the mixture to convert the metal salt particles into metal deposits on the surfaces of the ultra-hard particles, and HTHP sintering the mixture of ultra-hard particles with the metal deposits to form a polycrystalline ultra-hard material.

Abstract: Bulk, superhard, B—C—N nanocomposite compacts were prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture at a pressure in a range of from about 15 GPa to about 25 GPa, and sintering the pressurized encapsulated ball-milled mixture at a temperature in a range of from about 1800-2500 K. The product bulk, superhard, nanocomposite compacts were well sintered compacts with nanocrystalline grains of at least one high-pressure phase of B—C—N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compacts had a measured Vicker's hardness in a range of from about 41 GPa to about 68 GPa.

Abstract: A cermet and method of forming the cermet, the cermet including a Sialon and an alloy comprising nickel aluminide and boron, wherein the Sialon includes silicon aluminum oxynitride, and wherein at least a portion of the Sialon is bonded with at least a portion of the alloy. In one example, the cermet is about 70 weight percent to about 90 weight percent of the Sialon, and about 10 weight percent to about 30 weight percent of the alloy.

Abstract: The aluminum-nitride-based composite material according to the present invention is an aluminum-nitride-based composite material that is highly pure with the content ratios of transition metals, alkali metals, and boron, respectively as low as 1000 ppm or lower, has AlN and MgO constitutional phases, and additionally contains at least one selected from the group consisting of a rare earth metal oxide, a rare earth metal-aluminum complex oxide, an alkali earth metal-aluminum complex oxide, a rare earth metal oxyfluoride, calcium oxide, and calcium fluoride, wherein the heat conductivity is in the range of 40 to 150 W/mK, the thermal expansion coefficient is in the range of 7.3 to 8.4 ppm/° C., and the volume resistivity is 1×1014 ?·cm or higher.

Abstract: The present invention relates to a process of producing an aluminum nitride sintered body which satisfies both high thermal conductivity and reduction in the shrinkage factor at the time of sintering. The aluminum nitride sintered body is a sintered body of a powder mixture containing an aluminum nitride powder and a sintering aid, characterized by having a thermal conductivity of at least 190 W/m·K and a shrinkage factor represented by the percentage of {(dimensions of the molded body before sintering)?(dimensions of the sintered body after sintering)}/(dimensions of the molded body before sintering) of at most 15%.

Abstract: A method for manufacturing a ceramic heater includes mixing a conductive ceramic powder, an insulating ceramic powder, a sintering aid powder, and a solvent so as to obtain a slurry, drying the slurry so as to obtain a heating-element material powder, forming a green resistance-heating element from the heating-element material powder, embedding the green resistance-heating element in a ceramic substrate, and firing a resultant assembly. Water is used as the solvent. Drying of the slurry is performed by use of a fluidized-bed drying apparatus, a rotary drying apparatus, or a vibratory drying apparatus and, the apparatus being employed in combination with a medium for pulverization.

Abstract: The invention includes methods of forming an aluminum oxynitride-comprising body. For example, a mixture is formed which comprises A:B:C in a respective molar ratio in the range of 9:3.6-6.2:0.1-1.1, where “A” is Al2O3, “B” is AlN, and “C” is a total of one or more of B2O3, SiO2, Si—Al—O—N, and TiO2. The mixture is sintered at a temperature of at least 1,600° C. at a pressure of no greater than 500 psia effective to form an aluminum oxynitride-comprising body which is at least internally transparent and has at least 99% maximum theoretical density.

Abstract: A dense polycrystalline aluminum oxynitride body is produced. According the method of production, aluminum oxide (alumina) powder and 26 to 40 mole % aluminum nitride powder is mixed to form a very fine powder mixture. The powder mixture is shaped and hot pressed at a moderate temperature, preferably about 1600° C., which is below the temperature of aluminum oxynitride (AlON) formation to produce a dense intermediate body. The dense intermediate body is reacted to produce a highly dense polycrystalline aluminum oxynitride body. The dense body is particularly useful for ballistic armor.

Abstract: A conductive silicon nitride composite sintered body having an average grain size of 100 nm or less and whose relative roughness (Ra) after electric discharge machining is 0.3 ?m or less can be obtained by grinding/mixing a silicon nitride powder and a metal powder together until the average particle size of the silicon nitride powder becomes 30 nm or less, and subsequently by molding and sintering. It is preferable that the crushing/mixing is continued until it is apparent that a peak of added metal in an X-ray diffraction pattern has disappeared during the crushing/mixing.

Abstract: In the production of a silicon nitride sintered body through a hot press method, a sintering aid protecting agent is added to the raw material. The employable protecting agents are metallic elements such as Ta, W and Mo and compounds of the metallic elements such as nitrides and silicides. Conversion of these elements and compounds to carbides occurs preferentially to reduction of the sintering aid. Thus, it becomes possible to suppress reduction of the sintering aid in a reducing atmosphere formed, for example, of carbon monoxide, which is generated particularly when a graphite pressing die is employed.

Abstract: The invention comprises ferroelectric vapor deposition targets and to methods of making ferroelectric vapor deposition targets. In one implementation, a ferroelectric physical vapor deposition target has a predominate grain size of less than or equal to 1.0 micron, and has a density of at least 95% of maximum theoretical density. In one implementation, a method of making a ferroelectric physical vapor deposition target includes positioning a prereacted ferroelectric powder within a hot press cavity. The prereacted ferroelectric powder predominately includes individual prereacted ferroelectric particles having a maximum straight linear dimension of less than or equal to about 100 nanometers. The prereacted ferroelectric powder is hot pressed within the cavity into a physical vapor deposition target of desired shape having a density of at least about 95% of maximum theoretical density and a predominate maximum grain size which is less than or equal to 1.0 micron.

Abstract: The present invention provides a silicon nitride wear resistant member composed of silicon nitride sintered body containing 1-10 mass % of rare earth element in terms of oxide thereof as sintering agent, wherein a total oxygen content of the silicon nitride sintered body is 6 mass % or less, a porosity of the silicon nitride sintered body is 0.5 vol. % or less, and a maximum size of pore existing in grain boundary phase of the silicon nitride sintered body is 0.3 &mgr;m or less. According to the above structure of the present invention, there can be provided a silicon nitride wear resistant member and a method of manufacturing the member having a high strength and a toughness property, and particularly excellent in sliding characteristics.

Abstract: The invention comprises ferroelectric vapor deposition targets and to methods of making ferroelectric vapor deposition targets. In one implementation, a ferroelectric physical vapor deposition target has a predominate grain size of less than or equal to 1.0 micron, and has a density of at least 95% of maximum theoretical density. In one implementation, a method of making a ferroelectric physical vapor deposition target includes positioning a prereacted ferroelectric powder within a hot press cavity. The prereacted ferroelectric powder predominately includes individual prereacted ferroelectric particles having a maximum straight linear dimension of less than or equal to about 100 nanometers. The prereacted ferroelectric powder is hot pressed within the cavity into a physical vapor deposition target of desired shape having a density of at least about 95% of maximum theoretical density and a predominate maximum grain size which is less than or equal to 1.0 micron.

Abstract: A method for manufacturing molded articles from a ceramic composite structure, in particular from a combination of tri-silicon tetranitride and a metal silicide, in which gas pressures up to 100 bar are used and the sintering additive content can be reduced to under 10 mass percent. This inert gas sintering pressure method makes possible larger molding free spaces in complicated geometrical structures of the molded articles, in contrast to the known methods. In addition, the electrical properties of this composite structure can be regulated by adjusting a defined nitrogen partial pressure.

Abstract: Wear resistant member comprises a silicon nitride sintered body. Silicon nitride sintered body contains from 75 to 97% by mass of silicon nitride, from 0.2 to 5% by mass of titanium nitride and from 2 to 20% by mass of a grain boundary phase essentially containing Si—R—Al—O—N compound (R: rare earth element). Particles of titanium nitride are 1 &mgr;m or less in long axis. Particles of titanium nitride are mainly spherical particles of which aspect ratio is in the range of from 1.0 to 1.2, surface thereof being formed edgeless and roundish. Wear resistant member formed of such silicon nitride sintered body is excellent in strength, fracture toughness and rolling fatigue life. In particular, being excellent in rolling fatigue life, it is suitable for bearing member such as bearing balls.

Abstract: A method comprising incorporation of an inorganic polymer precursor of a grain growth inhibitor into nanostructured materials or intermediates useful for the production of nanostructured materials. The precursor/nanostructured material composite is optionally heat treated at a temperature below the grain growth temperature of the nanostructured material in order to more effectively disperse the precursor. The composites are then heat treated at a temperature effective to decompose the precursor and to form nanostructured materials having grain growth inhibitors uniformly distributed at the grain boundaries. Synthesis of the inorganic polymer solution comprises forming an inorganic polymer from a solution of metal salts, filtering the polymer, and drying. Alloying additives as well as grain growth inhibitors may be incorporated into the nanostructured materials.

Abstract: A sintered ceramic part to be exposed to a corrosive gas, a surface of said ceramic part being machined, wherein each of grains exposed to the machined surface of the ceramic part is formed with a machined surface, and en edge of the machined surface of each of these grains is made round by material transfer. A process for producing such a sintered ceramic part includes the steps of: obtaining a machined body having a given shape by at least grinding a surface of a ceramic sintered body, and annealing the machined body.

Abstract: The present invention relates to a method for sintering of a silicon nitride based material using gas pressure sintering technique. It has been found that using a sintering atmosphere containing nitrogen and 0.1-10 vol-% carbon monoxide a cutting tool material is obtained with improved properties, particularly increased edge toughness, when machining heat resistant alloys.

Abstract: A ceramic having a relatively high proportion of an alpha prime SiAlON phase and exhibiting high hardness and toughness. In a particularly preferred embodiment, a cation of Gd is used as a modifying cation.

Abstract: A semiconductor-supporting device comprising a substrate made of an aluminum nitride-based ceramic material and having a semiconductor-placing surface, wherein an orientation degree of the aluminum nitride-based ceramic material specified by the following formula is not less than 1.1 and not more than 2.0.Orientation degree=[I'(002)/I'(100)]/[I(002)/I(100)]in which in an X-ray diffraction measurement, I'(002) is a diffraction intensity of a (002) face of the aluminum nitride-based ceramic material when X-rays are irradiated from the semiconductor-placing surface, I'(100) is a diffraction intensity of a (100) face of the aluminum nitride-based ceramic material when X-rays are irradiated from the semiconductor-placing surface, I(002) is a diffraction intensity of the (002) face of the aluminum nitride ceramic according to a JCPDS Card No. 25-1133, and I(100) is a diffraction intensity of the (100) face of the aluminum nitride ceramic according to a JCPDS Card No. 25-1133.

Abstract: Titanium carbo-nitride complex silicon nitride tool is composed mainly of titanium carbo-nitride and silicon nitride and contains 10 to 56 wt % of Ti, 11.6 to 51 wt % of Si and 1 to 21 wt % in total of one or two or more of Ce, Y, Yb and Dy. The tool is mainly composed of Si.sub.3 N.sub.4 superior in both strength and resistance against thermal shock and TiCN superior in the effect of suppressing reactivity of Si.sub.3 N.sub.4 with Fe and exhibiting high hardness. By using oxides CeO.sub.2, Y.sub.2 O.sub.3, Yb.sub.2 O.sub.3 and Dy.sub.2 O.sub.3 as sintering aid so that the sum of the amounts of Ce, Y, Yb and Dy will be in the above range, both the resistance against flank notch (wear) of the end edge and resistance against thermal shock are improved resulting in improved durability as compared to the conventional silicon nitride cutting tool.

Abstract: A hard sintered body for a tool contains 25 to 47 vol. % of cBN, 40 to 70 vol. % and especially less than 45 vol. % in total of a carbo-nitride, and a boride of Ti, and 2 to 20 vol. % in total of a boride and a nitride of Al. In the carbo-nitride of Ti, the ratio of carbon to nitrogen is in the range of 60:40 to 30:70. In this hard sintered body, cBN particles are bonded to each other through binder phases. The obtained hard sintered body for a tool is excellent in wear resistance and chipping resistance for high-speed cutting of hardened steel.

Abstract: A hot press method for the fabrication of doped or undoped gallium nitride compacts, and of other nitride compacts, employs as a starting material a powder mixture of the selected nitride and of a nitrogen rich salt. A preferred method for fabricating gallium nitride compacts employs ammonium carbonate powder as a starting material additive. In the course of the hot press operation, the endothermic volatilization of ammonium carbonate at a temperature below the disassociation temperature threshold of gallium nitride acts to cool the gallium nitride and also releases free nitrogen radicals that are available to replace any nitrogen lost by gallium nitride molecules through disassociation. The resulting compacts are substantially free of gallium metal, voids, or contaminants, and have a density exceeding 75% of theoretical maximum density.

Abstract: A composite sintered body of silicon carbide and silicon nitride having a nano-composite structure in which fine SiC particles are dispersed in Si.sub.3 N.sub.4 particles and grain boundaries and fine Si.sub.3 N.sub.4 particles are dispersed in SiC particles is produced by (a) adding at least one sintering aid, boron and carbon to a mixed powder of silicon carbide and silicon nitride to form a green body, the sintering aid being (i) Al.sub.2 O.sub.3 or AlN and/or (ii) at least one oxide of an element selected from Groups 3A and 4A of the Periodic Table, and (b) sintering the green body by HIP or by a high-temperature normal sintering method.

Abstract: A method is disclosed for making a microwave radar transparent window material operable at temperatures above 2000.degree. C., and which material possesses high tensile strength, is resistant to .erosion as well as particle impact at such temperatures, and is highly machinable. The method comprises: blending a powder mixture of 20-60% by weight silicon nitride, 12-40% boron nitride, 15-40% boron nitride, 15-40% silica, and 1-20% oxygen carrying sintering aids; (b) molding the mixture to shape as a preform; and (c) densifying the shaped preform into a monolithic window having high temperature stability and transparency at high temperatures.