Abstract: An aluminum nitride particle including at least a first truncated six-sided pyramid (1-a) and a second truncated six-sided pyramid (1-b), the aluminum nitride particle having a shape such that a lower base (3) of the first truncated six-sided pyramid (1-a) and a lower base (3) of the second truncated six-sided pyramid (1-b) face each other, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) each having an upper base (2) with an area S1 of not less than 60 ?m2 and not more than 4800 ?m2, and each having a ratio (S1/S2) of the area S1 to an area S2 of the lower base (3) being not less than 0.5 and less than 1, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) respectively having a height h1 and a height h2 each being not less than 5 ?m and not more than 20 ?m.

Abstract: An aluminum nitride particle including at least a first truncated six-sided pyramid (1-a) and a second truncated six-sided pyramid (1-b), the aluminum nitride particle having a shape such that a lower base (3) of the first truncated six-sided pyramid (1-a) and a lower base (3) of the second truncated six-sided pyramid (1-b) face each other, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) each having an upper base (2) with an area Si of not less than 60 ?m2 and not more than 4800 ?m2, and each having a ratio (S1/S2) of the area Si to an area S2 of the lower base (3) being not less than 0.5 and less than 1, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) respectively having a height h1 and a height h2 each being not less than 5 ?m and not more than 20 ?m.

Abstract: An aluminum nitride particle including: a plurality of planes randomly arranged in a surface of the particle, the plurality of planes forming an obtuse ridge part or an obtuse valley part in the surface of the particle, the plurality of planes being observable in a scanning electron micrograph with 500 times magnification; wherein the particle has a longer diameter L of 20 to 200 ?m; a ratio L/D of the longer diameter L (unit: ?m) to a shorter diameter D (unit: ?m) of the particle is 1 to 1.25; and the plurality of planes comprise a first plane, wherein an area S (unit: ?m2) of the first plane satisfies S/L?1.0 ?m.

Abstract: To provide an aluminum nitride particle having a hexagonal columnar barrel part and bowl-like projection parts at both ends of the columnar part, wherein the long diameter (D) of the barrel part is 10 to 250 ?m, the ratio (L1/D) of the distance (L1) between the apexes of the two projection pars to the long diameter (D) of the barrel part is 0.7 to 1.3, and the percentage of the length or thickness (L2) of the barrel part to the distance (L1) between the apexes of the two projection parts is 10 to 60%. The aluminum nitride particle can provide high heat conductivity and excellent electric insulation to a resin when it is filled into the resin.

Abstract: An aluminum nitride particle including: a plurality of planes randomly arranged in a surface of the particle, the plurality of planes forming an obtuse ridge part or an obtuse valley part in the surface of the particle, the plurality of planes being observable in a scanning electron micrograph with 500 times magnification; wherein the particle has a longer diameter L of 20 to 200 ?m; a ratio L/D of the longer diameter L (unit: ?m) to a shorter diameter D (unit: ?m) of the particle is 1 to 1.25; and the plurality of planes comprise a first plane, wherein an area S (unit: ?m2) of the first plane satisfies S/L?1.0 ?m.

Abstract: Aluminum nitride crystal particles, aluminum nitride powders containing the same, production processes for both of them, an organic polymer composition comprising the aluminum nitride crystal particles and a sintered body. Each of the aluminum nitride crystal particles has a flat octahedral shape in a direction where hexagonal faces are opposed to each other, which is composed of two opposed hexagonal faces and 6 rectangular faces, in which the average distance “D” between two opposed corners of each of the hexagonal faces is 3 to 110 ?m, the length “L” of the short side of each of the rectangular faces is 2 to 45 ?m, and L/D is 0.05 to 0.8; each of the hexagonal faces and each of the rectangular faces cross each other to form a curve without forming a single ridge; and the true destiny is 3.20 to 3.26 g/cm3.

Abstract: To provide an aluminum nitride particle having a hexagonal columnar barrel part and bowl-like projection parts at both ends of the columnar part, wherein the long diameter (D) of the barrel part is 10 to 250 ?m, the ratio (L1/D) of the distance (L1) between the apexes of the two projection pars to the long diameter (D) of the barrel part is 0.7 to 1.3, and the percentage of the length or thickness (L2) of the barrel part to the distance (L1) between the apexes of the two projection parts is 10 to 60%. The aluminum nitride particle can provide high heat conductivity and excellent electric insulation to a resin when it is filled into the resin.

Abstract: After a wet blasting treatment for jetting a slurry, which contains spherical alumina as abrasive grains in a liquid, to the surface of a ceramic substrate 10 of aluminum nitride sintered body so that the ceramic substrate 10 has a residual stress of not higher than ?50 MPa and so that the surface of the ceramic substrate 10 to be bonded to the metal plate 14 has an arithmetic average roughness Ra of 0.15 to 0.30 ?m, a ten-point average roughness Rz of 0.7 to 1.1 ?m and a maximum height Ry of 0.9 to 1.

Abstract: A method for producing sintered aluminum nitride granules includes a reduction nitridation step of carrying out the reduction nitridation of porous alumina granules at a temperature of 1400 to 1700° C. inclusive to produce porous aluminum nitride granules; and a sintering step of sintering the porous aluminum nitride granules, which are produced in the reduction nitridation step, at a temperature of 1580 to 1900° C. inclusive.

Abstract: Provided is a method for producing a water-resistant aluminum nitride powder capable of adding a good water-resistant property to an aluminum nitride powder wherein yttria exists on a particle surface. The method is for producing a water-resistant aluminum nitride powder by carrying out a treatment to a particle surface of an aluminum nitride powder, the method including the successive steps of (i) making an aluminum nitride powder contact with an acid solution wherein yttria exists at least on a particle surface of the aluminum nitride powder; and (ii) making the aluminum nitride powder contact with a phosphorous acid compound, wherein the amount of yttria which is extracted when the aluminum nitride powder is filtered, washed with water, and dried after the step (i) and is thereafter subjected to extraction with 1 mol/L hydrochloric acid is no more than 1000 mg per 100 g of the aluminum nitride powder.

Abstract: A method for producing sintered aluminum nitride granules includes a reduction nitridation step of carrying out the reduction nitridation of porous alumina granules at a temperature of 1400 to 1700° C. inclusive to produce porous aluminum nitride granules; and a sintering step of sintering the porous aluminum nitride granules, which are produced in the reduction nitridation step, at a temperature of 1580 to 1900° C. inclusive.

Abstract: Aluminum nitride crystal particles, aluminum nitride powders containing the same, production processes for both of them, an organic polymer composition comprising the aluminum nitride crystal particles and a sintered body. Each of the aluminum nitride crystal particles has a flat octahedral shape in a direction where hexagonal faces are opposed to each other, which is composed of two opposed hexagonal faces and 6 rectangular faces, in which the average distance “D” between two opposed corners of each of the hexagonal faces is 3 to 110 ?m, the length “L” of the short side of each of the rectangular faces is 2 to 45 ?m, and L/D is 0.05 to 0.8; each of the hexagonal faces and each of the rectangular faces cross each other to form a curve without forming a single ridge; and the true destiny is 3.20 to 3.26 g/cm3.

Abstract: After a wet blasting treatment for jetting a slurry, which contains spherical alumina as abrasive grains in a liquid, to the surface of a ceramic substrate 10 of aluminum nitride sintered body so that the ceramic substrate 10 has a residual stress of not higher than ?50 MPa and so that the surface of the ceramic substrate 10 to be bonded to the metal plate 14 has an arithmetic average roughness Ra of 0.15 to 0.30 ?m, a ten-point average roughness Rz of 0.7 to 1.1 ?m and a maximum height Ry of 0.9 to 1.

Abstract: A method for producing an aluminum nitride powder includes mixing an alumina powder having an average particle diameter of not more than 5 ?m; an eutectic melting agent; and a carbon powder are mixed to obtain a mixture thereof, and reductively nitriding the mixture by firing at a higher temperature than a melting point of the eutectic melting agent, while maintaining a nitrogen ratio within a range of 60 to 85 vol % in an atmosphere of mixed gases of nitrogen and carbon monoxide until a nitriding ratio of the alumina powder reaches at least 50%.

Abstract: Provided is a method for producing a water-resistant aluminum nitride powder capable of adding a good water-resistant property to an aluminum nitride powder wherein yttria exists on a particle surface. The method is for producing a water-resistant aluminum nitride powder by carrying out a treatment to a particle surface of an aluminum nitride powder, the method including the successive steps of (i) making an aluminum nitride powder contact with an acid solution wherein yttria exists at least on a particle surface of the aluminum nitride powder; and (ii) making the aluminum nitride powder contact with a phosphorous acid compound, wherein the amount of yttria which is extracted when the aluminum nitride powder is filtered, washed with water, and dried after the step (i) and is thereafter subjected to extraction with 1 mol/L hydrochloric acid is no more than 1000 mg per 100 g of the aluminum nitride powder.

Abstract: A method for producing an aluminum nitride powder includes mixing an alumina powder having an average particle diameter of not more than 5 ?m; an eutectic melting agent; and a carbon powder are mixed to obtain a mixture thereof, and reductively nitriding the mixture by firing at a higher temperature than a melting point of the eutectic melting agent, while maintaining a nitrogen ratio within a range of 60 to 85 vol % in an atmosphere of mixed gases of nitrogen and carbon monoxide until a nitriding ratio of the alumina powder reaches at least 50%.

Abstract: An aluminum nitride single crystal in the form of polygonal columns, the polygonal columns having the following properties [a] to [c]: [a] the content of a metal impurity is below a detection limit, [b] the average bottom area is from 5×103 to 2×105 ?m2, and [c] the average height is 50 ?m to 5 mm. The above aluminum nitride single crystal is preferably obtainable in a method including the steps of sublimating an aluminum nitride starting material (A) containing 0.1 to 30% by mass of a rare earth oxide by heating the starting material at a temperature of not lower than 2000° C., depositing aluminum nitride on a hexagonal single crystal substrate and thereby growing aluminum nitride single crystal in the shape of polygonal columns.

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: Provided is an aluminum nitride sintered body with high optical transmissivity and which has a smooth surface in the unpolished condition after firing. The aluminum nitride sintered body has an oxygen concentration of 450 ppm or less, a concentration of impurity elements excluding oxygen, nitrogen, and aluminum of 350 ppm or less, and an average crystal grain diameter of between 2 ?m and 20 ?m, and also has an arithmetic mean surface height Ra of 1 ?m or less and a maximum height Rz of 10 ?m or less in the unpolished condition after firing.

Abstract: A high-purity aluminum nitride sintered body is provided by efficiently removing oxides contained in a raw material powder in producing an aluminum nitride sintered body and preventing composite oxide produced by reaction of oxides contained in the raw material powder with a sintering aid from remaining in the aluminum nitride sintered body. The above sintered body is achieved by an aluminum nitride sintered body having a concentration of residual oxygen excluding attached oxygen of 350 ppm or less.