| 摘要 |
PURPOSE:To obtain magnetic particle powder having good sphericity, grain size uniformity and large bulk density by oxidizing the ferrous hydroxide colloid obtd. by preliminarily adding water soluble silicate to a starting raw material while heating the same under prescribed conditions. CONSTITUTION:An aq. terrous salt soln. and 0.8-0.99 equiv. (with respect to ferrous salt) alkali hydroxide preliminarily added with the water soluble silicate are brought into reaction. A liquid contg. 0.1-5atomic% (in terms of Si with respect to Fe) said silicate and contg. the ferrous hydroxide colloid is prepd. While the liquid is kept heated to 70-100 deg.C, an oxygencontg. gas is permeated therethrough to oxidize the ferrous hydroxide. Further, >=1 equiv. (with respect to the remaining ferrous salt) alkali hydroxide is added thereto under the same heating and oxidizing conditions mentioned above. The magnetic particle powder having body centered cubic structure (X-ray diffraction diagram) of 0.5-2g/cm<3> bulk density and >=90emu/g saturation mangetization is thus obtd. |
