Abstract: This invention aims to provide a method of manufacturing a cerium-based abrasive containing coarse particles in lower concentration and having higher polishing ability and excellent cleanability for a polished face. Further, the present invention provides a method of manufacturing a cerium-based abrasive, including the steps of pulverizing a raw material, roasting a raw material after pulverization and disintegrating a raw material after roasting, in which a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a cerium-based abrasive raw material, and the step of pulverizing a raw material pulverizes a raw material through heating while the material is kept immersed in aqueous solution.

Abstract: A polishing material is provided in which the dispersibility of the abrasive grains of the polishing material having, as a major component, rare earth oxides including cerium oxide is made better and the hardness of abrasive grain precipitates is reduced, and at the same time high efficiency of polishing can be achieved stably. According to the present invention, in a polishing material having, as the major component, rare earth oxides including cerium oxide, any one of crystalline cellulose, calcium secondary phosphate, a condensate of sodium &bgr;-naphthalenesulphonate and formalin, and synthetic silica is contained as an anti-solidification agent capable of softening abrasive grain precipitates of the polishing material when the abrasive grains of the polishing material are dispersed into a dispersion medium, and sodium hexametaphosphate or pyrophosphate is contained as a dispersant capable of dispersing the abrasive grains of the polishing material into the dispersion medium.

Abstract: This invention aims to provide a method of manufacturing a cerium-based abrasive containing coarse particles in lower concentration and having higher polishing ability and excellent cleanability for a polished face. Further, the present invention provides a method of manufacturing a cerium-based abrasive, including the steps of pulverizing a raw material, roasting a raw material after pulverization and disintegrating a raw material after roasting, in which a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a cerium-based abrasive raw material, and the step of pulverizing a raw material pulverizes a raw material through heating while the material is kept immersed in aqueous solution.

Abstract: Disclosed herein is a method for producing potassium fluorotantalate crystals, comprising heating, to 60° C. or higher, a starting solution prepared by adding hydrofluoric acid and hydrochloric acid, and, if necessary, water to a highly pure tantalum solution, adding potassium chloride to this starting solution, and cooling the mixture to 40° C. or lower at a cooling rate of less than 15° C./h to precipitate potassium fluorotantalate crystals, wherein the concentration of the hydrofluoric acid in the starting solution is not more than 20% by weight. By this method, highly pure, large-sized potassium fluorotantalate crystals can successfully be obtained in high yield. Moreover, disadvantages to equipment and operation in the prior art can be overcome to a significant extent with this method.

Abstract: A polishing material is provided in which the dispersibility of the abrasive grains of the polishing material having, as a major component, rare earth oxides including cerium oxide is made better and the hardness of abrasive grain precipitates is reduced, and at the same time high efficiency of polishing can be achieved stably. According to the present invention, in a polishing material having, as the major component, rare earth oxides including cerium oxide, any one of crystalline cellulose, calcium secondary phosphate, a condensate of sodium &bgr;-naphthalenesulphonate and formalin, and synthetic silica is contained as an anti-solidification agent capable of softening abrasive grain precipitates of the polishing material when the abrasive grains of the polishing material are dispersed into a dispersion medium, and sodium hexametaphosphate or pyrophosphate is contained as a dispersant capable of dispersing the abrasive grains of the polishing material into the dispersion medium.

Abstract: Disclosed herein is a method for producing potassium fluorotantalate crystals, comprising heating, to 60° C. or higher, a starting solution prepared by adding hydrofluoric acid and hydrochloric acid, and, if necessary, water to a highly pure tantalum solution, adding potassium chloride to this starting solution, and cooling the mixture to 40° C. or lower at a cooling rate of less than 15° C./h to precipitate potassium fluorotantalate crystals, wherein the concentration of the hydrofluoric acid in the starting solution is not more than 20% by weight. By this method, highly pure, large-sized potassium fluorotantalate crystals can successfully be obtained in high yield. Moreover, disadvantages to equipment and operation in the prior art can be overcome to a significant extent with this method.

Abstract: A furnace for the heat treatment of wire materials, comprising a cylindrical furnace body having holes at both ends through which a wire material is inserted into and out of the furnace body, a combustion chamber formed within the furnace body, a burner provided at one end portion of the furnace body and adjacent to the combustion chamber, and a discharge pipe mounted near the downstream edge of the combustion chamber for discharging the waste gas. The burner comprises a free space through which the wire material is inserted, a fuel-air mixture chamber surrounding the free space, and injection nozzles communicating with the fuel-air mixture chamber and serving to inject the mixture into the combustion chamber. The injection nozzles are arranged to permit the injected streams of fuel-air mixture to make whirling motions in the same direction along the inner wall of the combustion chamber in such a manner as to be free from direct contact with the wire material running along the axis of the combustion chamber.