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.

Abstract: .alpha.-Silicon nitride powder which is used as a raw material for the preparation of high strength silicon nitride with additives such as magnesia and yttrium oxide, and other sintered materials suitable for high temperatures gas turbine engine components and the like, is prepared by heating a powdered mixture of silica, carbon and at least one component selected from the group consisting of silicon nitride, silicon carbide and silicon oxynitride in a nitrogen containing atmosphere and then optionally subjecting the material to a heat treatment in an oxidizing atmosphere for decarbonization of said material as required.

Abstract: Disclosed is a method of producing a sintered body of ceramics, wherein a powder mixture consisting, essentially of at most 10%, exclusive of 0%, by weight of yttrium oxide, at most 10%, exclusive of 0%, by weight of aluminum oxide, at most 10%, exclusive of 0%, by weight of aluminum nitride, at most 5%, exclusive of 0%, by weight of at least one material selected from the group consisting of titanium oxide, magnesium oxide and zirconium oxide, and the balance essentially of silicon nitride is sintered under a non-oxidizing atmosphere.

Abstract: A method for producing powder of a .alpha.-silicon nitride which comprises the steps of adding 0.1 to 2 parts by weight of carbon and 0.005 to 1 part by weight of at least one silicon compound selected from the group consisting of Si.sub.3 N.sub.4, SiC and Si.sub.2 ON.sub.2 to one part by weight, when converted to SiO.sub.2, of a liquid alkylchlorosilane that forms a precipitate and HCl by hydrolysis which precipitate is convertible to SiO.sub.2 at a baking temperature of 1300.degree. to 1550.degree. C., hydrolyzing the resultant mixture, washing the mixture to separate a solid component, and baking the solid component at a temperature of 1300.degree. to 1550.degree. C. in an atmosphere mainly consisting of a nitrogen gas or a gas of a nitrogen compound to effect formation of .alpha.-silicon nitride.

Abstract: Disclosed is a method of producing a sintered body of ceramics, wherein a powder mixture consisting, essentially of at most 10%, exclusive of 0%, by weight of yttrium oxide, at most 10%, exclusive of 0%, by weight of aluminum oxide, at most 10%, exclusive of 0%, by weight of aluminum nitride, at most 5%, exclusive of 0%, by weight of at least one material selected from the group consisting of titanium oxide, magnesium oxide and zirconium oxide, and the balance essentially of silicon nitride is sintered under a non-oxidizing atmosphere.

Abstract: A method for producing powder of .alpha.-silicon nitride which comprises the steps of:adding 0.3 to 2 parts by weight of powder of carbon and 0.005 to 1 paret by weight of at least one silicon compound selected from the group consisting of Si.sub.3 N.sub.4, SiC and silicon oxide nitride series compounds to one part by weight (as converted to SiO.sub.2) to a liquid silane derivative which produces a precipitate and HCl by hydrolysis and further causes SiO.sub.2 to be grown by the baking of said precipitate, or the precipitate produced by hydrolysis of the liquid silane derivatives;hydrolyzing the resultant mixture, if necessary;washing the mixture to separate a solid component, if necessary; andbaking the solid component for reduction and nitrogenization at a temperature of 1300.degree. to 1500.degree. C. in an atmosphere mainly consisting of a nitrogen gas or a gas of a nitrogen compound.

Abstract: A method of producing a silicon carbide powder consisting of fine particles of uniform shape and size, comprising baking at 1,350.degree. to 1,850.degree. C. under a non-oxidizing atmosphere a powdery mixture consisting of 1 part by weight of silica powder or a compound forming silica powder at high temperatures, carbon powder or a compound forming carbon powder at high temperatures, and silicon carbide or a substance forming silicon carbide at high temperatures, the amounts of the silica powder-forming compounds, the carbon powder-forming compounds and the silicon carbide powder-forming substance being determined such that the amounts of the formed powders are equal to those specified above.

Abstract: An apparatus includes a sealed vessel, a crucible received in the sealed vessel to hold a first molten liquid of III-V compound semiconductive material and a second molten liquid of an encapsulating material overlying the first molten liquid, and floating member having an opening for defining the cross sectional outline of a single crystal while being grown and positioned in the interface between the first and second molten liquids. The floating member is made from a mixed material consisting essentially of at least one of oxides of yttrium and the lanthanum series elements, alumina and silicon nitride each in a prescribed amount.

Abstract: .alpha.-Silicon nitride powder which is used as a raw material for the preparation of high strength silicon nitride with additives such as magnesia and yttrium oxide, and other sintered materials suitable for high temperature gas turbine engine components and the like, is prepared by heating a powdered mixture of silica, carbon and metallic silicon in a nitrogen containing atmosphere and then subjecting the material to a heat treatment in an oxidizing atmosphere for decarbonization of said material.

Abstract: A method for manufacturing heat-resistant reinforced composite materials having a fibrous structure which comprises mixing 99.8 to 90 percent by weight of a first component selected from the group consisting of the nitrides or carbides of aluminum, silicon and boron and mixtures thereof and 0.2 to 10 percent by weight of a second component selected from the group consisting of the rare earth oxides and mixtures thereof, molding the mixture into a desired shape, and sintering the molded mass to create a fibrous structure therein, said first component being 0.2 to 3.0 microns in average particle size, and said second component being 0.1 to 2.0 microns in average particle size.

Abstract: We had previously disclosed a heat resistive and reinforced composite material which was prepared by sintering a finely powdered mixture of trisilicon tetranitride and an oxide of yttrium group elements.More improved similar composite material having excellent bending strength can be obtained by sintering a finely powdered mixture of trisilicon tetranitride, yttrium oxide and aluminum oxide. Cerium oxide, lanthanum oxide or scandium oxide can also be used instead of yttrium oxide.