Dowa Electronics Materials Co., Ltd.

Dowa F-tec Co., Ltd.

Nippon Bengara Kogyo Co., Ltd.

Hideki Katayama

Shuichi Kohayashi

Masayasu Senda

Keisuke Ayabe

Shinichi Suenaga

Hiroya Ikeda

To provide ferrite magnetic powders for bond magnet capable of surely suppressing residual hexavalent chrome, being an environmental load substance, having no adverse influence on the magnetic characteristics, which is an obstacle in use, and without damaging productivity and at a low cost. The method includes the steps of obtaining sintered powders by sintering raw material powders; wet-pulverizing the sintered powders; wet-cleaning the sintered powders; and annealing the cleaned sintered powders, wherein in the step of the wet-pulverization and in the step of wet-cleaning, generation of the hexavalent chrome, being an environmental load substance, is suppressed by performing the pulverization and cleaning while maintaining pH of a dispersion solvent at 8.5 or less, at the time of pulverization and cleaning.

Ferrite magnetic powder for bond magnet and manufacturing method of the same, and bond magnet

A ferrite magnetic powder for bonded magnets bonded using a rubber-base resin as binder, which powder is a ferrite magnetic powder containing an alkaline earth metal and having a chlorine content of 0.05 wt % or less and a powder pH of less than 6. The magnetic powder is produced by pulverizing a calcinated product of ferrite composition containing an alkali earth metal, annealing the pulverized ferrite composition to relieve crystal strain, dispersing the annealed powder in water and adding to it a mineral acid, adding a dispersant thereto, and subjecting the dispersion to solid-liquid separation followed by vacuum drying to obtain a ferrite magnetic powder having a chlorine content of 0.05 wt % or less and a powder pH of less than 6.

Ferrite magnetic powder and method for production thereof

Growing community of inventors

Okayama, Japan

Hideki Katayama