| 摘要 |
PURPOSE:To improve various stabilities of coercive forces by coating the surfaces of particles of magnetic oxidized iron powder with cobalt compound or cobalt compound and ferrous compound and then covering with zinc compound. CONSTITUTION:gamma-Fe2O3 is dispersed in water as slurry, aqueous cobalt sulfate solution and aqueous ferrous sulfate solution are added while blowing N2 gas into the solution, and the mixture is then stirred. Aqueous NaOH solution is then added, and cobalt compound and ferrous compound are covered on the surfaces of the particles of the Fe2O3. Aqueous solution containing zinc sulfate and aqueous NaOH solution which is slightly excess to the neutral equivalent of the salt are added to cover with zinc compound. This slurry is filtered, washed with water, obtained wet cake is heat treated in N2 gas, and dried. |
