| 摘要 |
PURPOSE:To improve erasing characteristics of Co-coating magnetic iron oxide powder by forming a film made of silicon compound on the surfaces of the particles of magnetic iron oxide powder, and further forming a film made of Co ferrite on the film made of the silicon compound. CONSTITUTION:A film made of silicon compound is formed on the surfaces of the particles of magnetic iron oxide powder, and a film made of Co ferrite is formed on the film made of the silicon compound. It is preferable that the film made of the silicon compound contains 0.005-0.03 of Si by weight with respect to the whole Co-coating magnetic iron oxide power and the film made of the Co ferrite thereon contains 0.01-0.10 of Co by weight with respect to the whole powder. The film made of the silicon compound is preferably formed of silicon oxide of silicon hydrate oxide. Hydroxide of the Co and the Fe is normally deposited on the surface, and heat treated at 100 deg.C or lower to form the Co ferrite layer. |
