Abstract: Disclosed is a method of manufacturing aluminum nitride, which comprises the steps of preparing a mixed gas consisting essentially of an ammonia gas and at least 0.5% by volume of a hydrocarbon gas, calcining .gamma.-Al.sub.2 O.sub.3 or a precursor thereof at 300.degree. to 1,100.degree. C. so as to prepare the .gamma.-Al.sub.2 O.sub.3 having a moisture content of 1 weight % or less; heating the calcined .gamma.-Al.sub.2 O.sub.3 in the mixed gas at a temperature of 1,200.degree. to 1,700.degree. C., thereby preparing porous aluminum nitride having a specific surface area of 10 m.sup.2 /g or more; and heat-treating the porous aluminum nitride in an atmosphere of an ammonia gas, or a mixed gas of an ammonia gas and an inert gas, at 1600.degree. to 2000.degree. C., so as to make contents of both carbon and oxygen contained in the aluminum nitride 1 weight % or less.

Abstract: Quartz material is subjected to a heat contact treatment with ammonia gas at 1200.degree. C. less under the presence of a carbon generating source to form a silicon oxynitride layer on the surface of the quartz material easily and rapidly. The obtained surface-treated quartz material has excellent heat resistance, and no exfoliation of the silicon oxynitride layer from the quartz material occurs even when it is subjected to a repetitive heat cycle. Further, if a second surface treatment step of coating a silicon nitride film on the silicon oxynitride layer using a CVD method or the like is performed after the surface treatment step of forming the silicon oxynitride layer on the surface of the quartz material, the heat resistance is more improved.

Abstract: Aluminium borate whiskers by which a composite material having a higher strength than ever is available by definitely suppressing a generation of spinel along the surface of the whiskers are prepared by heating aluminium borate whiskers bearing a r-alumina surface layer in an atmosphere of ammonia gas or ammonia gas and a hydrocarbon gas such that a layer of a nitro-oxide and oxide of aluminium is generated along the surface of the whiskers.

Abstract: A gasket for use in internal combustion engines characterized in that one or both surfaces of a metallic or non-metallic sheet thereof are coated with a coat layer of a thickness of from 10 to 300 .mu.m composed of a coating material comprising from 20 to 60% by weight of expanded graphite having a specific volume of from 10 to 300 cc/g and from 40 to 80% by weight of a binder such as a synthetic resin.

Abstract: A heat-resistant alloy having excellent properties at high temperatures and useful for producing exhaust valves, comprises, in weight %, not more than 0.10% C, not more than 2.0% Si, not more than 2.0% Mn, from 35 to 50% Ni, from 17 to 25% Cr, from 3.2 to 5% Mo, from 2.0 to 3.2% Ti, from 0.5 to 1.5% Al, with the balance consisting essentially of Fe, wherein the weight ratio of Ti/Al is not more than 5/1. The alloy may further comprise at least one of B, Ca, and Mg, and/or at least one of Nb and Ta.

Abstract: A valve sealing device is proposed consisting of two parts, one of which contacts the body of the valve and is made of an expanded graphite compact or an expanded graphite--inorganic binder composite compact, and the other of which contacts the valve member and is made of a carbonaceous material--metallic material composite, a carbonaceous material impregnated with an inorganic binder, or a metallic material; a valve using such a sealing device is also proposed.