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: 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 silicon single crystal pulling-up apparatus includes a silica glass crucible for accommodating a melted silicon material, a cylindrical member made of a carbon composite material which is composed of a carbon fiber wound round a cylinder, impregnated with a resin and carbonized, disposed on an upper end of a cylindrical portion of the crucible for accommodating the melted silicon in association with the cylindrical portion of the crucible, a wall thickness of the cylindrical member being not more than 3 mm, a rotational shaft for rotating the crucible, and a crucible support fixed to an upper end of the rotational shaft for supporting the crucible.

Abstract: A silicon single crystal pull-up apparatus includes a crucible for containing a molten silicon material, an annular heater disposed so as to surround the crucible for heating the silicon material in the crucible, and a plurality of plate-like members made of heat insulation material and disposed so as to surround the heater, each of the plate-like members has an arc-shaped cross section not less than a two-third circle and is connected with each other at respective side edges thereof such that the plurality of the plate-like members are assembled into a shape of a cylinder having wave-like circumferential side walls.

Abstract: A method for impregnating a shaped ceramic material with an impregnation liquid, comprising the steps of placing the shaped ceramic material in the impregnation liquid, and applying an impregnation pressure to the impregnation liquid through a pressure transfer liquid so that the shaped ceramic material is impregnated with the impregnation liquid.

Abstract: A method for impregnating a shaped ceramic material with an impregnation liquid, comprising the steps of placing the shaped ceramic material in the impregnation liquid, and applying an impregnation pressure to the impregnation liquid through a pressure transfer liquid so that the shaped ceramic material is impregnated with the impregnation liquid.

Abstract: A semiconductor element heat-treatment member has a Si-SiC body and a SiO.sub.2 coating formed on the surface of the Si-SiC body so as to cover the Si-SiC body. The SiO.sub.2 coating has a thickness ranging between 20.ANG. and 100,000.ANG..

Abstract: An alumina composite body comprising a plurality of elongated alumina elements oriented in random directions and interconnected so as to constitute a porous matrix, and aluminum and silicon tightly filling the porous matrix; and a method of manufacturing an alumina composite body comprising reacting a body of silica, or a body of a silicon compound such as silicon carbide or silicon nitride which has been at least partially oxidized to produce silica, with aluminum so as to change the silica into alumina.

Abstract: An alumina formed body comprising many long alumina elements oriented in random directions and interconnected so as to constitute a porous matrix comprising a large number of fine pores. Such a body is manufactured by reacting a glass-formed body comprising silica with aluminum at high temperature to form an alumina composite material comprising alumina, aluminum and silicon and removing aluminum and silicon from the aluminum composite material.

Abstract: An apparatus for producing silicon single crystal from melted silicon by the pull-up process using a seed crystal, wherein at least a portion of a device in contact with the melted silicon includes a layer of silicon nitride precipitated from gaseous phase and comprising 20% or above of .beta. phase, or comprising 80% or above of .alpha. phase whose crystal grains have grain diameters of 5 .mu.m or above at a ratio of 10% or more.