| 摘要 |
PURPOSE:To form a uniform and dense oxide film on a surface of a ferromagnetic metallic powder particle, by performing low-temperature holding of ferromagnetic metallic powder grains with organic solvent-impregnated iron as a main ingredient and next by using an oxygencontained gas to ventilate these grains and dry them and further by heating them to raise their temperature. CONSTITUTION:Ferromagnetic powder grains with iron as a main ingredient are dipped into toluene and put into a rotary reaction device. While its internal temperature is held to be 20 deg.C, they are stirred and ventilated by a mixed gas containing oxygen of one volume % in its concentration. This operation is continued until toluene in the device disappears. While the internal temperature is held afterwards, the oxygen concentration of the mixed gas is increased by 1% per hour. After the concentration reaches 5%, the reaction is performed for four hours. While the concentration is held to be 5%, the internal temperature is continuously raised at the rate of 1 deg.C/hr. The reaction is stopped at 50 deg.C and the magnetic powder grains are taken out in the air. Magnetic characteristics of this magnetic powder are shown by 1510Oe in its coercive force, 125emu/g in the amount of its saturated magnetization, and 0.515 in its square ratio. |
