| 摘要 |
PURPOSE:To prevent the surface of ferromagnetic metallic particulates from being oxidized while the ferromagnetic metallic particulates are preserved by treating the surface of the ferromagnetic metallic particulates with a dithionite solution. CONSTITUTION:2.0g of ferromagnetic metallic particulates is added to 50ml of dithionite solution. It is left as it is for about two hours. In order to prevent oxidation of ferromagnetic metallic powder due to contact with air, the work should be done in an airtight state. The treated solution is filtrated using a film filter and then the obtained ferromagnetic metallic particulates are vacuum-dried at 30 deg.C for eight hours to obtain treated powder. It is known that the ferromagnetic metallic particulates surface-treated with dithionite of every kind has saturation magnetization 73 and a coercive force Hc, both of which deteriorate very small, and has a stabilized magnetic characteristic with the passage of time. Since the ferromagnetic metallic particulates are surface-treated with dithionite such as Na2S2O4 or ZnS2O4) and thereby a dithionite film is formed on the surface of the ferromagnetic metallic particulates, the ferromagnetic metallic particulates are provided with a resistance to oxidation and therefore a change of saturation magnetization with the passage of time is held low. |
