Abstract: The invention provides Al2O3 dispersion-strengthened Ti2AlN composites, wherein Ti2AlN matrix and Al2O3 strengthening phase both are reactively formed in situ. The volume fraction of Al2O3 is 5% to 50%; the particle size of Al2O3 ranges from 500 nm to 2 ?m, with the mean size of Al2O3 particles about 0.8 ?m to 1.2 ?m; the shape of Ti2AlN grain is plate-like about 80 nm to 120 nm thick and 0.5 ?m to 2 ?m long. The composites exhibit excellent deformability at high temperature under compression and flexure stresses, and possess excellent oxidation resistance at 1100° C. to 1350° C. for long time (100 h). The composites show typical metallic conductor behavior and the electrical resistivity at room temperature is 0.3 to 0.8 ??·m. The invention also provides a method for preparing the same: First, nanoparticles in Ti—Al binary system were prepared in continuous way by hydrogen plasma-metal reaction (HPMR) using Ti—Al alloy rods with Al content 20% to 60% by atom, or pure Al rods and pure Ti rods.

Abstract: The present invention relates to 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: The present invention relates to a material for use at temperatures exceeding 1200° C. and in oxidizing atmospheres consisting generally of an alloy between a metal, aluminium (Al) and carbon (C) or nitrogen (N). The invention is characterized in that the alloy has a composition MZAlYXW where M essentially consists of titanium (Ti), chromium (Cr) and/or niobium (Nb) and where X is carbon (C) or where X is nitrogen (N) and/or carbon (C) when M is titanium (Ti); and in that z lies in the range of 1.8 to 2.2, y lies in the range of 0.8-1.2 and w lies in the range 0.8-1.2, and wherein a protective oxide layer of Al2O3 is formed after heating to the mentioned temperature.

Abstract: A method for improving surface thermal shock resistance of a member made of ceramics to which thermal shock resistance is required comprising, forming homogeneously distributed linear dislocation structure on the surface of the member made of ceramics to which thermal shock resistance is required by blasting abrasives composed of fine particles whose average particle size is from 5 ?m to 200 ?m and whose surface shape is convex, wherein Vickers hardness (HV) of said fine particles is 800 or more and equal to or less than the hardness of the member made of ceramics to which thermal shock resistance is required.

Abstract: The object of the present invention is to provide a susceptor with superior thermal uniformity by minimizing pores in an aluminum nitride sintered body. In an aluminum nitride sintered body according to the present invention, the tin content and sulfur content are controlled so that they are no more than a fixed amount. More specifically, in an aluminum nitride sintered body having as its main component aluminum nitride, the tin content in the aluminum nitride sintered body is no more than 50 ppm and the sulfur content is no more than 100 ppm. It would be preferable for a resistance heating body to be formed in the aluminum nitride sintered body and it would be preferable for the aluminum nitride sintered body to be used as a semiconductor heating unit.

Abstract: An aluminum nitride sintered body comprising crystal grains of an average grain size (D50) of 0.1 to 2.5 ?m, and having a pore area ratio of not larger than 1×10?7, a pore density of not larger than 0.05 pores/mm2 of pores having diameters of not smaller than 1 ?m, and a Vickers' hardness in a range of 14 to 17 GPa. The aluminum nitride sintered body has a very small pore density despite of its relatively small crystal grain size, features excellent strength and mirror machinability, and is particularly useful as a material for circuit substrates on which fine wiring patterns are formed.

Abstract: This disclosure describes sintered bodies comprising about 90 wt % to about 99 wt % of boron carbide, having a B:C atomic ratio ranging from 3.8 to 4.5:1; 0 to 1 wt % free carbon; 0 to 1 wt % BN or AlN, remainder an oxide binder phase; said sintered body having a uniform microstructure composed of substantially equiaxed grains of said boron carbide; the oxide binder phase comprising at least a rare earth aluminate and optionally Al2O3 or other ternary or binary phases of rare earth oxide-alumina systems; the binder phase being present in form of pockets at the multiple grain junctions and the density of no more than 2.6 g/cm3. Also described is a manufacturing process for the above described substantially pore-free, sintered boron carbide materials with high strength and fracture toughness, which can be used for production of large-area parts. This is achieved by liquid phase low temperature-low pressure hot pressing of boron carbide in an argon atmosphere.

Abstract: An aluminum nitride sintered body is provided, including a polycrystalline structure in which grain boundary fracture toughness KICgb is 1.6 MPa·m1/2 or more. The grain boundary fracture toughness KICgb is determined by the equation KICgb=KIC·cos2(?·PIF/200), wherein KIC is fracture toughness (MPa·m1/2), and PIF is a percentage of the intergranular fracture (%).

Abstract: The present inventors have found that an aluminum nitride sintered body excellent in flatness by polishing can be provided by improving the strength of a grain boundary; at the same time, by adding SiO2 or MgO, which forms a solid solution with aluminum nitride during a sintering process, with the result that it is no longer present as a grain boundary phase, in a small amount to an aluminum nitride powder, followed by sintering the aluminum nitride powder at a low temperature from more than 160° C. to less than 1750° C.

Abstract: A conductive channel formed of an (Sm, Ce)Al11O18 is interconnected in the grain boundaries of aluminum nitride (AlN) particles, thereby reducing temperature dependency of volume resistivity of AlN sintered body; at the same time, the solid solution of the AlN particles is formed with at least one of C and Mg, to prevent the conductive channel from moving in AlN particles, thereby maintaining the volume resistivity within AlN particles at a high value even at a high temperature.

Abstract: The present invention is to produce an aluminum nitride powder which is turned into a sintered body at a temperature of not more than 1600° C., thereby obtaining a sintered aluminum nitride in which the density and thermal conductivity are high and which can be properly used as a substrate material. Using a vapor phase reaction apparatus shown in FIG. 1, ammonia gas was fed from a reactor 2 heated at from 300 to 500° C. and maintained at that temperature by a heating section 1 via a feeding tube 4 while being regulated by a flow regulator 3. At the same time, while being regulated by the flow regulator 5, nitrogen gas containing an organic aluminum compound is fed via a feeding tube 6 to obtain an aluminum nitride powder. The aluminum nitride powder is subjected to a heat treatment at from 1100 to 1500° C. in a reducing gas atmosphere and/or an inert gas atmosphere to obtain an aggregate aluminum nitride powder.

Abstract: A translucent polycrystalline material suitable for use in ceramic discharge vessels for metal halide lamps is produced by sintering an alumina powder doped with a MgO sintering aid in a nitrogen atmosphere containing a partial pressure of a vapor phase carbon-containing species. The sintered polycrystalline alumina has a grain boundary phase containing aluminum, oxygen and nitrogen. The formation of the AL—O—N grain boundary phase is believed to facilitate the transport of nitrogen from entrapped pores during sintering. Preferably, the PCA is sintered in a carbon-element furnace under flowing ultra-high-purity nitrogen.

Abstract: Transparent polycrystalline sintered ceramic of cubic crystal structure. The invention relates to the field of technical ceramic and relates to transparent polycrystalline sintered ceramics of cubic crystal structure for applications with increased mechanical stress, e.g., as protective or armoring ceramic. Provided are sintered ceramics that combine a high transmission of RIT>75% of the theoretical maximum value with a distinctly improved hardness. Transparent polycrystalline sintered ceramics of cubic crystal structure with a real in-line transmission RIT>75% of the theoretical maximum value measured on 0.8 mm-thick polished plates and for light of a wavelength between 600 and 650 nm, and with an average grain size D in the range of 60 nm<D<10 ?m are provided.

Abstract: An aluminum nitride ceramic including aluminum nitride grains and grain boundary phases comprises a grain boundary phase-rich layer including more amount of the grain boundary phases in a surface layer of the aluminum nitride ceramic than in an inside of the aluminum nitride ceramic. The grain boundary phases in the grain boundary phase-rich layer include at least one of rare earth element and alkali earth element.

Abstract: A substrate holding structure having excellent corrosion resistance and airtightness, excellent dimensional accuracy and sufficient durability when mechanical or thermal stress is applied thereto is obtained. A holder (1) serving as the substrate holding structure includes a ceramic base (2) for holding a substrate, a protective cylinder (7) joined to the ceramic base (2) and a joining layer (8) positioned therebetween for joining the ceramic base (2) and the protective cylinder (7) to each other. The joining layer (8) contains at least 2 mass % and not more than 70 mass % of a rare earth oxide, at least 10 mass % and not more than 78 mass % of aluminum oxide, and at least 2 mass % and not more than 50 mass % of aluminum nitride. The rare earth oxide or the aluminum oxide has the largest proportional content among the aforementioned three types of components in the joining layer (8).

Abstract: An aluminum nitride ceramic having a low volume resistivity at room temperature and a relatively low samarium content is provided. The aluminum nitride ceramic contains aluminum nitride as a main component and samarium in a converted content, calculated as samarium oxide, of 0.060 mole percent or lower. The aluminum nitride ceramic includes aluminum nitride particles and a samarium-aluminum composite oxide phase having a length of at least 7 ?m.

Abstract: A novel aluminum nitride material having a low room temperature volume resistivity is provided. The aluminum nitride material has an aluminum nitride main component and includes at least 0.03 mol % of europium oxide. The aluminum nitride material has an aluminum nitride phase and an europium-aluminum composite oxide phase. An aluminum nitride material also provided having an aluminum nitride main component, wherein a total content of europium oxide and samarium oxide is at least 0.09 mol %. The aluminum nitride material has an aluminum nitride phase and a composite oxide phase containing at least europium and aluminum.

Abstract: A refractory article for use in casting operations wherein said article is subject to prolonged contact with molten metal of at least 1500° C. for at least three hours, said article comprises a ceramic composite consisting essentially of about 10 to about 40 wt. % mullite; about 35 to about 5 wt. % aluminium nitride; and at least about 20 wt. % boron nitride, for forming a reactive coating layer covering at least 80% of exposed surfaces and providing corrosion/erosion protection for said article against molten metal.

Abstract: An apparatus and method for fabricating a mount for an aluminum nitride (AlN) seed for single crystal aluminum nitride growth is provided. A holder having a proximal base and wall portions extending therefrom is fabricated from crystal growth crucible material, and defines an internal cavity. An AlN seed is placed within the holder, and placed within a nitrogen atmosphere at a temperature at or exceeding the melting point of a suitable material capable of forming a nitride ceramic by nitridation, such as aluminum. Pellets fabricated from this material are dropped into the holder and onto the seed, so that they melt and react with the nitrogen atmosphere to form a nitride ceramic. The seed is effectively molded in-situ with the ceramic, so that the ceramic and holder forms a closely conforming holder for the seed, suitable for single crystal AlN growth.

Abstract: An aluminum nitride sintered body having an oxygen concentration of not larger than 400 ppm, a metal impurity concentration of not larger than 150 ppm, and a carbon concentration of not larger than 200 ppm, and having an average crystal grain size of 2 ?m to 20 ?m. The sintered body exhibits particularly excellent optical properties such as an inclination of a spectral curve in the wavelength region of 260 to 300 nm of not smaller than 1.0 (%/nm), a light transmission factor of not smaller than 86% in the wavelength region of 400 to 800 nm, and a wavelength of not longer than 400 nm when the light transmission factor reaches 60% in the spectrum.

Abstract: An objective of the present invention is to provide an aluminum nitride sintered body making it possible to keep a volume resistivity of 108 ?·cm or more, and guarantee covering-up capability, a large radiant heat amount and measurement accuracy with a thermoviewer. A carbon-containing aluminum nitride sintered body of the present invention of the present invention comprising: carbon whose peak cannot be detected on its X-ray diffraction chart or whose peak is below its detection limit thereon; in a matrix made of aluminum nitride.

Abstract: An aluminum nitride sintered body produced by sintering under pressure of a powder composition comprising aluminum nitride and 5 to 30% by weight of at least one sintering aid selected from the group consisting of Nd, Sm, Eu, Er, Dy, Gd, Pr and Yb, per 100% by weight of the powders of aluminum nitride and the sintering aid, wherein the amount of the sintering aid is a conversion value as oxides of the elements, the sintering body that has been subjected to mirror-polishing having a surface roughness R max of 0.2 ?m or less and a thermal conductivity of 200 (W/mK) or more.

Abstract: An aluminum nitride ceramic is provided, including 0.5 to 10 weight percent of boron atoms and 0.1 to 2.5 weight percent of carbon atoms. The ceramic has a room temperature volume resistivity not lower than 1×1014?·cm, and a volume resistivity at 500° C. of not lower than 1×108?·cm. An a-axis lattice constant of the aluminum nitride in the ceramic is not shorter than 3.112 angstrom and a c-axis lattice constant of the aluminum nitride is not shorter than 4.980 angstrom.

Abstract: An aluminum nitride material having a high thermal conductivity and reduced room temperature volume resistivity is provided. The aluminum nitride material has an interconnected intergranular phase that functions as an electrically conductive phase. The content of the conductive phase is not higher than 20 percent, calculated according to the following formula based on an X-ray diffraction profile: Content of the conductive phase (%)=(Integrated strength of the strongest peak of the conductive phase/Integrated strength of the strongest peak of aluminum nitride phase)×100. The aluminum nitride material has an electric current response index in a range of 0.9 to 1.1, defined according to the following formula: Electric current response index=(Electric current Aat 5 seconds after a voltage is applied/Electric current at 60 seconds after a voltage is applied).

Abstract: A hard film for cutting tools which is composed of (Ti1?a?b?c?d, Ala, Crb, Sic, Bd) (C1?eNe) 0.5?a?0.8, 0.06?b, 0?c?0.1, 0?d?0.1, 0?c+d?0.1, a+b+c+d<1, 0.5?e?1 (where a, b, c, and d denote respectively the atomic ratios Al, Cr, Si, and B, and e denotes the atomic ratio of N.

Abstract: An objective of the present invention is to provide an aluminum nitride sintered body making it possible to keep a volume resistivity of 108 ?•cm or more, and guarantee covering-up capability, a large radiant heat amount and measurement accuracy with a thermoviewer. A carbon-containing aluminum nitride sintered body of the present invention of the present invention comprising: carbon whose peak cannot be detected on its X-ray diffraction chart or whose peak is below its detection limit thereon: in a matrix made of aluminum nitride.

Abstract: A ceramic substrate for a semiconductor producing/examining device which has high fracture toughness value, excellent thermal shock resistivity, high thermal conductivity and an excellent temperature rising and falling properties, can be used as a hot plate, an electrostatic chuck, a wafer prober and the like. A ceramic substrate, for a semiconductor producing/examining device, having a conductor formed inside or on the surface thereof has been sintered such that a fractured section thereof exhibits intergranular fracture.

Abstract: An aluminum nitride ceramic is provided, containing boron atoms in an amount of not lower than 1.0 weight percent and carbon atoms in an amount of not lower than 0.3 weight percent and having a volume resistivity at room temperature of not higher than 1×1012 ?·cm. The aluminum ceramic comprises aluminum nitride and an intergranular phase mainly consisting of boron nitride constituting a conductive path. Such a ceramic may be obtained by holding a mixture containing at least aluminum nitride and boron carbide at a holding temperature in a range of 1400° C. to 1800° C. and then sintering the mixture at a maximum temperature that is higher than the holding temperature.

Abstract: An objective of the present invention is to provide an aluminum nitride sintered body making it possible to keep a volume resistivity of 108&OHgr;·cm or more, and guarantee covering-up capability, a large radiant heat amount and measurement accuracy with a thermoviewer. A carbon-containing aluminum nitride sintered body of the present invention of the present invention comprising: carbon whose peak cannot be detected on its X-ray diffraction chart or whose peak is below its detection limit thereon; in a matrix made of aluminum nitride.

Abstract: A nanocomposite having titanium aluminum carbon nitride and amorphous carbon is disclosed, and the nanocomposite comprises a titanium aluminum carbon nitride grain of nanometer scale and an amorphous carbon matrix, wherein the titanium aluminum carbon nitride grain of nanometer scale is embedded into the amorphous carbon matrix. The method for coating the nanocomposite of titanium aluminum carbon nitride-amorphous carbon on a substrate comprises: depositing the substrate in a reaction chamber; and igniting plasma to clean and remove an oxide layer and adsorptive on the substrate; injecting a reaction gas. The reaction gas is activated and thermal decomposed by plasma to form the nanocomposite coating layer of titanium aluminum carbon nitride-amorphous carbon on the surface of the substrate.

Abstract: An object of the present invention is to provide a carbon-containing aluminum nitride sintered body wherein no short circuit is caused since its volume resistivity at a high temperature range of 200° C. or higher (for example, about 500° C.) is sufficiently high, that is, at least 1×108 &OHgr;·cm or more, and also wherein covering-up capability, a large radiant heat amount and measurement accuracy with a thermoviewer can be assured. The carbon-containing aluminum nitride sintered body of the present invention is comprising carbon whose peaks appear near 1580 cm−1 and near 1355 cm−1 in laser Raman spectral analysis in a matrix made of aluminum nitride.

Abstract: An aluminum nitride sintered body contains aluminum nitride as a main component, at least one rare earth metal element in an amount of not less than 0.4 mol % and not more than 2.0 mol % as calculated in the form of an oxide thereof and aluminum oxide component in an amount of not less than 0.5 mol % and not more than 2.0 mol %. Si content of the sintered body is not more than 80 ppm and an average particle diameter of aluminum nitride grains is not more than 3 &mgr;m. The aluminum nitride sintered body hardly peels aluminum nitride grains and exhibits high resistivity of at least 108 &OHgr;·cm even in a high temperature range of, for example, 300-500° C., as well as relatively high thermal conductivity.

Abstract: An object of the present invention is to provide a novel aluminum nitride material of aluminum nitride base and having a low volume resistivity at room temperature. An aluminum nitride material has aluminum nitride as a main component and europium in a content of 0.03 mole percent or more calculated as the oxide, and the material has aluminum nitride and an europium-aluminum composite oxide phases. Alternatively, an aluminum nitride material has aluminum nitride as a main component and europium and samarium in a total content of 0.09 mole percent or more calculated as the oxides, and the material has aluminum nitride phase and a composite oxide phase containing at least europium and aluminum.

Abstract: An objective of the present invention is to provide an aluminum nitride sintered body making it possible to keep a volume resistivity of 108 &OHgr;·cm or more, and guarantee covering-up capability, a large radiant heat amount and measurement accuracy with a thermoviewer. A carbon-containing aluminum nitride sintered body of the present invention of the present invention comprising: carbon whose peak cannot be detected on its X-ray diffraction chart or whose peak is below its detection limit thereon; in a matrix made of aluminum nitride.

Abstract: The purpose of the present invention is to provide a method for manufacturing a ceramic substrate hardly causing cracks and damages and the like attributed to pushing pressure and the like since the strength of the above-mentioned ceramic substrate is higher than that of a conventional one even in the case of manufacturing a large size ceramic substrate capable of placing a semiconductor wafer with a large diameter and the like. The present invention is to provide a method for manufacturing a ceramic substrate having a conductor formed on the surface thereof or internally thereof, including the steps of: firing a formed body containing a ceramic powder to produce a primary sintered body; and performing an annealing process to the primary sintered body at a temperature of 1400° C. to 1800° C., after the preceding step.

Abstract: The invention concerns a wear-resistant coating on rotary metal-cutting tools such as drill bits, countersinks, milling cutters, screw taps, reamers, etc. The coating according to the invention consists essentially of nitrides of Cr, Ti and Al with a unusually high share of Cr atoms, namely 30 to 60% referred to the totality of metal atoms. In multilayer coatings and even more in coatings made of homogeneous mixed phases, this high Cr share results in particularly large tool life distances for the tools hardened with these coatings. These tools exhibit their superiority particularly during dry use without cooling lubricants or with minimal lubrication.

Abstract: An object of the present invention is to provide an aluminum nitride material having a high thermal conductivity and reduced volume resistivity at room temperature. An aluminum nitride material has interconnected intergranular phase functioning as electrical conductive phase. The material has a content of the conductive phase of not higher than 20 percent, calculated according to the following formula based on an X-ray diffraction profile. Content of the conductive phase (%)=(Integrated strength of the strongest peak of the conductive phase/Integrated strength of the strongest peak of aluminum nitride phase)×100. Alternatively, the material has an electric current response index of not lower than 0.9 and not higher than 1.1 defined according to the following formula. Electric current response index=(Electric current at 5 seconds after a voltage is applied/Electric current at 60 seconds after a voltage is applied).

Abstract: A material with a low volume resistivity at room temperature composed of an aluminum nitride sintered body is provided. The sintered body contains samarium in a converted content calculated as samarium oxide of not lower than 0.04 mole percent. The sintered body contains an aluminum nitride phase and a samarium-aluminum complex oxide phase. The samarium-aluminum complex oxide phase forms intergranular layers with a low resistivity along the intergranular phase between aluminum nitride grains.

Abstract: An object of the present invention is to preserve the characteristic properties of an aluminum nitride ceramics and reduce its volume resistivity. An aluminum nitride ceramics contains boron atoms in an amount of not lower than 1.0 weight percent and carbon atoms in an amount of not lower than 0.3 weight percent and has a volume resistivity at room temperature of not higher than 1×1012 &OHgr;·cm. Alternatively, an aluminum ceramics comprises aluminum nitride and intergranular phases mainly consisting of boron nitride constituting a conducting path and has a volume resistivity at room temperature of 1×1012 &OHgr;·cm. Such ceramics may be obtained by holding a mixture at least containing aluminum nitride and boron carbide at a holding temperature not lower than 1400° C. and not higher than 1800 ° C. and then sintered at a maximum temperature higher than the holding temperature.

Abstract: It is an object of the present invention to increase the volume resistivity of an aluminum nitride ceramics. An aluminum nitride ceramics contains 0.5 to 10 weight percent of boron atoms and 0.1 to 2.5 weight percent of carbon atoms and having a volume resistivity at room temperature of not lower than 1×1014 &OHgr;·cm. Alternatively, the ceramics has a volume resistivity at 500° C. of not lower than 1×108 &OHgr;·cm. Alternatively, an aluminum nitride ceramics has an a-axis lattice constant of aluminum nitride not shorter than 3.112 angstrom and a c-axis lattice constant of aluminum nitride not shorter than 4.980 angstrom.

Abstract: An aluminum nitride sintered body is provided. The aluminum nitride has a polycrystalline structure of aluminum nitride crystals having an average particle diameter in a range of 5 &mgr;m to 20 &mgr;m and cerium in a range of 0.01 wt % 1.0 wt %, when calculated as an oxide thereof. The aluminum nitride sintered body has a room temperature volume resistivity in a range of 1×108 &OHgr;·cm to 1×1012 &OHgr;·cm under the application of 500 V/mm, and a value of a in the I-V relational equation, I=kV&agr;, is in a range of 1.0 to 1.5, V being a voltage in a range of 100 V/mm to 1000 V/mm, I being a leak current when V is applied to said aluminum nitride body, k being a constant, and &agr; being a non-linear coefficient.

Abstract: An aluminum nitride sintered body contains aluminum nitride as a main component, at least one rare earth metal element in an amount of not less than 0.4 mol % and not more than 2.0 mol % as calculated in the form of an oxide thereof and aluminum oxide component in an amount of not less than 0.5 mol % and not more than 2.0 mol %. Si content of the sintered body is not more than 80 ppm and an average particle diameter of aluminum nitride grains is not more than 3 &mgr;m. The aluminum nitride sintered body hardly peels aluminum nitride grains and exhibits high resistivity of at least 108 &OHgr;·cm even in a high temperature range of, for example, 300-500° C., as well as relatively high thermal conductivity.

Abstract: A sintered aluminum nitride having satisfactorily densified via holes, which is free from cracking and has excellent appearance, is produced through firing an aluminum nitride molding having at least one highly isolated through-hole for via hole formation. At least one through-hole for formation of dummy via holes not used for electrical connection is formed around the highly isolated through-hole for via hole formation, and the through-hole for dummy via hole formation is also filled with a conductive paste. Thereafter, the aluminum nitride molding is fired into the sintered aluminum nitride.

Abstract: A ceramic polycrystal and a method of manufacturing such a ceramic polycrystal having thermal stability enough to be used in an arc tube are provided. The ceramic polycrystal has crystalline particles. Each of crystalline particles has a crystalline structure selected from triclinc, monoclinic, rhombi, tetragonal, trigonal, and hexagonal systems, with an average grain size being not less than 5 &mgr;m and a linear transmittance being not less than 8%.

Abstract: A dry refractory composition having superior insulating value. The dry refractory composition also may have excellent resistance to molten metals and slags. The composition includes filler lightweight material, which may be selected from perlite, vermiculite, expanded shale, expanded fireclay, expanded alumina silica hollow spheres, bubble alumina, sintered porous alumina, alumina spinel insulating aggregate, calcium alumina insulating aggregate, expanded mulllite, cordierite, and anorthite, and matrix material, which may be selected from calcined alumina, fused alumina, sintered magnesia, fused magnesia, silica fume, fused silica, silicon carbide, boron carbide, titanium diboride, zirconium boride, boron nitride, aluminum nitride, silicon nitride, Sialon, titanium oxide, barium sulfate, zircon, a sillimanite group mineral, pyrophyllite, fireclay, carbon, and calcium fluoride.

Abstract: A ceramic material which is an orthorhombic boride of the general formula: AlMgB14:X, with X being a doping agent. The ceramic is a superabrasive, and in most instances provides a hardness of 40 GPa or greater.

Abstract: An aluminum nitride sintered body with high heat conductivity and high strength as well as a method of inexpensively manufacturing such an aluminum nitride sintered body at a low temperature are provided. The aluminum nitride sintered body is manufactured by adding a compound of at least one type of rare earth element (R) selected from La, Ce, Pr, Sm; and Eu, Y compound, Ca compound, and Al compound to an AlN powder and sintering the resulting mixture at a temperature of 1550° C. to 1750° C. The content of oxygen forming Al2O3 existing in an aluminate with rare earth element (R), Y and Ca and oxygen forming independently existing Al2O3 is calculated as 0.01 to 5.0% by weight, heat conductivity is 166 to 200 W/mK, and bending strength is at least 300 MPa.

Abstract: An aluminum nitride sintered product which is made mainly of aluminum nitride and contains an yttrium compound in an amount of from 0.6 to 5 wt % as calculated as yttrium oxide, a vanadium compound in an amount of from 0.02 to 0.4 wt % as calculated as vanadium and carbon in an amount of from 0.03 to 0.10 wt % and which has a three-point bending strength of at least 45 kg/mm and a thermal conductivity of at least 150 W/m·K, wherein crystal grains of aluminum nitride have an average grain size of at most 5 &mgr;m.

Abstract: A method of manufacturing oriented sintered ceramic product which enables to manufacture an oriented sintered product with an average crystal grain size of 20 &mgr;m or less and a grain width 0.4 times or less of the grain size, or an oriented sintered product with an average crystal grain size of 20 &mgr;m or more and a grain width 0.5 times or more of the grain size with no grain growth of plate-like seed crystals, the method comprising dispersing a non-ferromagnetic powder having a not-cubic crystal structure into a slurry, consolidating the slurry under a magnetic field and sintering the molding product.

Abstract: Dense, high thermal conductivity AIN ceramic is described (along with a method of manufacture) which can be used in microwave tubes as collector rods, Helix support rods, T rods, etc. instead of BeO ceramic. High thermal conductivity, vacuum compatibility, low dielectric loss tangent at microwave frequencies, high electrical resistivity and dielectric strength are AIN properties allowing the material to be used in traveling wave tubes, particle accelerators or as laser bores and in other similar applications. These materials allow the replacement of BeO, which is a toxic material with diminishing availability in the United States and on the world market.