| 摘要 |
PURPOSE:To prevent particles from sintering and getting out of shape when reducing and provide the powder having excellent magnetic characteristics, by coating the powder particles of oxy ferric hydroxide or ferric oxide with each compound of one or more compounds of zinc and alkaliearth metals and of a silicon compound to heat and reduce the particles. CONSTITUTION:The powder mainly comprising oxy ferric hydroxide or ferric oxide such as alpha-FeOOH or alpha-Fe2O3 is dispersed in the aqueous solution of one or more compounds of zinc sulfate, etc. and alkaliearth metal compounds and of a silicon compound such as Na4SiO4. The solution is neutralized by e.g. CO2 blowing or the addition of an acid to deposit the hydroxides and silicic acid sol. on the particles. In this process, the coating treatment with the Si compound need not be simultaneous but may be stepwise. The particles thus coating treatd are heated in a reducing atmosphere such as a hydrogen stream to provide the magnetic powder mainly comprising metallic iron. |
