| 摘要 |
PURPOSE:To obtain needle crystal iron alloy magnetic grain powder which has high coercive force and large saturation magnetization and is excellent in dispersion property and oxidation stability, by previously covering grain surface effectively with polymer of specified silicon compound. CONSTITUTION:Needle crystal water-containing ferric oxide grain, or needle crystal hematite grain obtained by heating and baking needle type water- containing ferric oxide grain or, needle crystal iron alloy magnetic grain obtained by heating and reducing them is brought into contact with silicon compound in vapor phase, thereby previously covering the grain surface effectively with silicon polymer whose general formula is (R1HSiO)a(R<2>R<3>SiO)b(R<4>R<5>R<6> SiO1/2)c. In the formula, R<1>-R<6> represent hydrocarbon radical whose number of carbon atoms is 1-10 which can be mutually independently hydroogen atom or by at lest one of halogen atoms (wherein R<1>-R<3> can not be hydrogen atom at the same time; (a) and (b) are 0 or integer larger than or equal to 1; (c) is 0 or 2. Thereby needle crystal iron alloy magnetic grain powder, which has high coercive force and large saturation magnetization and is excellent in dispersion property and oxidation stability, can be obtained. |
