Abstract: A SiC ceramic sintered body containing 0.05-5 atom % Sc, 10 atom % or less free carbon, 2 atom % or less oxygen, balance SiC, is described where 75% or more of the Sc is dissolved into the SiC grains.

Abstract: An SiC-based pressureless sintered product contains a sintered product main component containing grains of at least one additive selected from the group consisting of Tac, NbB.sub.2, VB.sub.2 and WB and the balance of SiC sintered grains constituting a SiC matrix, and a sintering assistant component. The additive grains have a maximum grain size not greater than an average grain size of the SiC sintered grains.

Abstract: A sialon based composite composite essentially consists of 5 wt % to 40 wt % of SiC fibers, 0.3 wt % to 10 wt % of an Hf component which is calculated in terms of Hf oxide, and the balance of sialon as a major constituent. In this case, the sialon is .alpha.-sialon or .beta.-sialon.

Abstract: There is disclosed an aluminum sintered body prepared by sintering aluminum nitride and additives, which consists essentially of(a) aluminum nitride,(b) at least one compound selected from the group consisting of an aluminum compound of a rare earth metal, an aluminum compound of an alkaline earth metal, and an aluminum compound of a rare earth metal and an alkaline earth metal, and(c) at least one element selected from the transition elements consisting of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one compound comprising the element, and the rare earth element, alkaline earth element and transition element are supplied by the additives.

Abstract: A process for producing aluminum nitride powder by reacting nitrogen gas with a mixture of alumina and carbon is disclosed, in which a solid organic compound is added to the mixture.

Abstract: There are disclosed an aluminum sintered body comprising(a) aluminum nitride,(b) at least one compound selected from the group consisting of an aluminum compound of a rare earth metal, an aluminum compound of an alkaline earth metal, and an aluminum compound of a rare earth metal and an alkaline earth metal, and(c) at least one element selected from the transition elements consisting of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one compound containing said element,and a process for preparing the same comprising mixing aluminum nitride with(i) at least one of compound selected from the group consisting of a rare earth metal and/or an alkaline earth metal; and(ii) at least one of element selected from the group consisting of a transition element of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one of a compound containing said element;and then molding and sintering the mixture.

Abstract: A silicon carbide sintered body containing not less than 0.03% by weight of boron, a total of not more than 0.3% by weight of metallic element impurities including the boron, not more than 1.0% by weight of free carbon, a total of not more than 0.15% by weight of non-metal impurities other than the free carbon, and the balance essentially consisting of silicon carbide, and having a density of not less 3.10 g/cm.sup.3. The sintered body is manufactured by heating a molding of a mixture containing a silicon carbide powder, a boron-containing sintering assistant, and a carbon-containing oxygen scavenger to a sintering temperature. The molded body is maintained at a temperature lower than the sintering temperature during the heating process until an oxide film covering the silicon carbide powder is substantially removed by the oxygen scavenger, and the molded body is then sintered at the sintering temperature under a non-pressurized condition.

Abstract: According to the present invention, there is provided an aluminum nitride sintered body having a high thermal conductivity and essentially consisting of a AlN single-phase, containing 0.01 to 8,000 ppm of rare earth elements and less than 2,000 ppm of oxygen. According to the present invention, there is provided a method of fabricating an aluminum nitride sintered body having a high thermal conductivity and essentially consisting of AlN single-phase, containing 0.01 to 8,000 ppm of rare earth elements and less than 2,000 ppm of oxygen, wherein a molded body prepared by mixing and molding an aluminum nitride power having less than 7 wt % of oxygen and an average particle size of 0.05 to 5 .mu.m and with rare earth compounds of 0.01 to 15 wt % of based on rare earth elements content, or a sintered AlN body containing oxide grain boundary phases of 0.01 to 15 wt % of rare earth elements and 0.

Abstract: An aluminum nitride-based sintered body having a high thermal conductivity and a total oxygen content of 0.01 to 20% by weight which is prepared by mixing a main component of aluminum nitride powder containing 0.001 to 7% by weight of oxygen with 0.01 to 15% by weight of at least one of the group consisting of a powder of a rare earth element and/or a powder of a material containing the rare earth element (said 0.01 to 15% by weight being counted on the basis of the content of the rare earth element), and sintering said powder mixture.

Abstract: A ceramic with anisotropic thermal conductivity, which has an aluminum nitride polytype layer arranged in a portion of an aluminum-nitride-based sintered body as a thermal barrier.

Abstract: Disclosed are an aluminum nitride sintered body comprising aluminum nitride, rare earth element-aluminum compounds and alkaline earth metal-aluminum compounds, and a process for producing an aluminum nitride sintered body, which comprises adding to aluminum nitride powder:(a) powder of at least one compound selected from the group consisting of rare earth element oxides, rare earth element fluorides and compounds capable of being converted into these oxides or fluorides by calcination, and(b) powder of at least one compound selected from the group consisting of alkaline earth metal oxides, alkali earth metal fluorides and compounds capable of being converted into these oxides or fluorides by calcination, in a total amount of 0.01 to 20 wt % as calculated on the weight of the oxides or the fluorides, and then molding and sintering the resultant mixture.

Abstract: A method of forming a nitride ceramic-metal complex material without using a special bonding material. This method comprises bringing a metallic material into contact with the surface of a nitride ceramic material, heating under vacuum the nitride ceramic material so as to dissociate the surface of the nitride ceramic material into nitrogen and a precursor of the ceramic material, thereby allowing the dissociated precursor to react with the metallic material and to achieve bonding between the nitride ceramic material and the metallic material. A nitride ceramic-metal complex material produced by the above method is also proposed.

Abstract: A process for preparing aluminum nitride powder, which comprises mixing (i) aluminum hydroxide powder, (ii) carbon powder or a substance capable of forming carbon powder by heating and (iii) at least one of additives selected from the group consisting of aluminum nitride powder, silicon nitride powder, silicon carbide powder and powder of substances capable of forming the powder corresponding to these powders, and baking the mixture thus obtained in a non-oxidative atmosphere containing nitrogen. The process is useful for preparing aluminum nitride powder having small particle size and small particle size distribution and also having a uniform shape of particles, at a lower temperature and in a shorter period of time.

Abstract: A high thermal conductivity circuit substrate is provided comprising a sintered aluminum nitride ceramic substrate consisting essentially of one member selected from the group of yttrium, the rare earth metals and the alkali earth metals and an electrically conductive thick film paste for a conductive layer formed on the substrate.

Abstract: A process for producing readily sinterable aluminum nitride powder, which comprises mixing(i) alumina powder and/or powder of a compound capable of forming alumina by heat treatment,(ii) carbon powder and/or powder of a compound capable of forming carbon by heat treatment, and(iii) powder of at least one compound selected from the group consisting of alkaline earth metal oxides, compounds capable of forming said alkaline earth metal oxides by heat treatment, rare earth element oxides and compounds capable of forming said rare earth element oxides by heat treatment,and calcining the resulting mixture in a nitrogen-containing non-oxidative atmosphere, provides an aluminum nitride powder which is readily sinterable without further mixing with a sintering aid.

Abstract: There is disclosed a method for preparing a coated powder comprising the steps of adding a carbon powder and an aluminum nitride powder to a methylsilicic acid powder or a precursor of the methylsilicic acid and mixing them and then subjecting the resulting mixed powder to a heat treatment in an atmosphere including an inert gas or a carbon component-containing gas in order to coat the aluminum nitride powder with silicon carbide.This invention provides a chemically stable coated powder and a sintered body obtained by employing the coated powder has a good thermal conductivity.

Abstract: Disclosed is a highly heat-conductive ceramic material which is basically of SiC-AlN system, comprising SiC, AlN and one or more of metal oxide selected from CaO, BaO and SrO, each in a prescribed amount. The SiC may otherwise be one whose particle surface is coated with the AlN.

Abstract: Disclosed is a process for preparing silicon nitride powder, which comprises baking a powdery mixture comprising (i) 1 part by weight of silica powder, or a silica-containing substance in terms of silica, (ii) 0.4 to 4 parts by weight of carbon powder, or a substance generating carbon by baking, in terms of carbon and (iii) 0.005 to 1 part by weight of silicon nitride powder synthesized by a silica reduction method, at a temperature of from 1350.degree. to 1550.degree. C. in a non-oxidative atmosphere containing nitrogen.

Abstract: Disclosed is a process for producing a sintered silicon nitride-base body, which comprises; mixing powder (A) of heat-treated or not heat-treated silicon nitride powder and powder (B) of powder obtained by heat-treating a powdery mixture of silicon nitride powder and a sintering additive in a non-oxidizing atmosphere and then grinding the resulting heat-treated products into powder; and forming the resultant powdery mixture into a desired shape, which is then sintered in a non-oxidizing atmosphere.The process is characterized by heating powder (B), or powder (A) and powder (B), before sintering, thereby producing sintered silicon nitride body of highly improved properties.

Abstract: There is disclosed a sintered body of aluminum nitride comprising a sintered body of powder mixture containing(a) AlN powder: 100 parts by weight,(b) at least one compound selected from CaO, BaO, SrO and a compound capable of being converted into one of these oxides by sintering : 0.05 to 6 parts by weight, and(c) carbon powder or powder of a compound capable of being converted into carbon by sintering : more than 0 to not more than 7 parts by weight.The sintered bodies of aluminum nitride according to this invention have high density and excellent properties such as high thermal conductivity.