FERRITE POWDER FOR BONDED MAGNET, METHOD FOR MANUFACTURING FERRITE POWDER, AND BONDED MAGNET USING FERRITE POWDER

摘要

A bonded magnet is required to have a large energy product, which is the product of magnetization Br and coercive force Hc. However, in a ferrite powder for a bonded magnet, when the particle diameter is reduced to improve the coercive force, the packing properties are impaired, and the Br is lowered.;When the particle diameter is increased to improve the magnetization, the coercive force is lowered.;Therefore, to increase the energy product, both the Br and Hc must be increased.;A ferrite powder that has a large particle size, is composed of smooth crystals, and suffers only a small reduction in coercive force even after pressurization is obtained by mixing a fine ferrite powder having a small particle size with a ferrite powder calcined at a temperature of 1050° C. to 1300° C. in the presence of a chloride at its saturated vapor pressure and then annealing the mixture at 800° C. to 1100° C.;A bonded magnet produced using the powder has an energy product of 2.0 MGOe or more.