| 摘要 |
PURPOSE:To obtain a ferromagnetic metal fine particles for magnetic recording medium excellent in oxidization resistance showing little secular deterioration for a long term by treating the surface of the particles with aq. soln. of boric acid or borate. CONSTITUTION:The surface of ferromagnetic metal particles is treated with an aq. soln. of boric acid or borate. As for the ferromagnetic metal fine particles, ferromagnetic metal material such as Fe, Co, Ni, etc., or ferromagnetic alloy material essentially comprising these elements are used. The boric acid ion in an borate aq. soln. used includes orthoboric acid ion, diboric acid ion, tetraboric acid ion and other polyboric acid ion. With this surface treatment, long-term stability and holding stability of magnetic characteristics can be significantly improved. |
