Abstract: A crystalline inorganic fiber or molded body thereof is thermally treated in gas atmosphere containing chlorine. The crystalline inorganic fiber or molded body thereof contains small impurities such as Fe, Cu and Ni. For example, Fe is 15 ppm or less, Cu is 1 ppm or less, and Ni is 0.5 ppm or less.

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: A .beta.-alumina electrocast refractory formed of a composition of 91-95 wt. % of Al.sub.2 O.sub.3, 2.0 wt. % or less of K.sub.2 O, 4.0-7.0 wt. % of Na.sub.2 O and K.sub.2 O in total, 0.15-2.0 wt. % of BaO, SrO and CaO in total, and 0.1 wt. % or less of Fe.sub.2 O.sub.3 and TiO.sub.2 in total.

Abstract: High-zirconia fused refractories consist essentially of 85-96 wt % of ZrO.sub.2, 3-8 wt % of SiO.sub.2, 0.1-2 wt % of Al.sub.2 O.sub.3, 0.05-3 wt % of B.sub.2 O.sub.3, 0.05-3 wt % of BaO, SrO and MgO in total, 0.05 wt % or more of Na.sub.2 O, 0.05-0.6 wt % of Na.sub.2 O and K.sub.2 O in total, and 0.3 wt % or less of Fe.sub.2 O.sub.3 and TiO.sub.2 in total, and does not substantially contain P.sub.2 O.sub.5 and/or CuO.

Abstract: A method of producing an electrocast brick or other ceramic shape, and the ceramic shape produced thereby, wherein the electrocast brick or other ceramic shape is cast in a mold which is formed, with a predetermined cavity shape and size, of quartz glass particles; the ceramic material of the ceramic shape may be Al.sub.2 O.sub.3 -ZrO.sub.2 -SiO.sub.2 ceramic, Al.sub.2 O.sub.3 -SiO.sub.2 ceramic or other heat meltable ceramic materials.

Abstract: A molten fiber material flow is rendered into a plurality of fibers by means of a liquid jet such as water jet in place of a pressurized gas or air. The flow moves downwardly in a vertical direction while the water jet cuts it at an inclined angle. The water jet is formed by a single nozzle or plural nozzles of a flat-jet or round-jet type.

Abstract: A refractory brick segment for use in a heat regenerator is made of an electrocast refractory material in the shape of a tube. The brick segment has a wall thickness of from 35 mm to 75 mm and a substantially rectangular cross-section. All of an inner side wall, an outer side wall and a corner wall have concave portions so as to have a total volume which is from 0.4 times or more to 0.85 times or less as large as that of a corresponding brick segment having no concave portions and a surface area per volume unit which is 1.5 times or more as large as that of a corresponding brick segment having no concave portions.

Abstract: In a refractory brick assembly for a heat regenerator, a plurality of brick units are assembled so as to form many long vertical gas flow passages. Each outer wall of the brick units has four corner portions each of which has a plurality of convex and concave strips. That can engage with each other so as to hold the brick units due to the friction between them. A high projection is formed on at least one of the inner and outer walls for producing a turbulent flow.

Abstract: A method for manufacturing a fused cast refractory article including the steps of pouring a molten refractory material into a cavity of a mold including a casting sand held by a negative pressure applied through the sand and against a thermoplastic film which surrounds the mold cavity, casting and cooling off the refractory material, wherein the negative pressure is maintained after the casting. The mold includes an upper mold portion including a frame, a casting sand, and a thermoplastic film; a bottom mold portion including a frame, a casting sand and a thermoplastic film; and a cavity defined by the thermoplastic film between the upper and bottom mold portion and having an inlet opening.

Abstract: In a heat regenerator, a unit body of a refractory unit has an upper end surface (1a), a lower end surface (1b), an outer wall (1c), an inner wall (1d) and a flow passage (7) which is formed by the inner wall (1c) and extends between both end surfaces (1a, 1b). The outer wall (1c) includes a series of concave and convex strips (4). The inner wall (1d) includes a series of concave and convex strips (5).