| 摘要 |
PURPOSE:To prepare the titled finely divided powder having large specific surface area of particle and narrow particle size distribution, by blending a compound of Ba, Sr, Pb, etc. with iron oxide in the presence of water-glass, calcining the blend at a proper temperature, grinding it. CONSTITUTION:At least one compound of metal elements such as Ba, Sr, or Pb is blended with iron oxide in a given ratio in the presence of water-glass. An amount of the water-glass added is properly 0.05-1.45wt% calculted as SiO2 based on iron oxide (calculated as Fe2O3). The blend is then calcined in a 750- 900 deg.C temperature range, ground by a grinder such as an atomizer, etc., to give finely divided powder of ferrite of magnetoplumbite type having a composition with a molar ratio of Fe2O3/MO (M is one or more of Ba, Sr, and Pb) of 5.6- 6.1. The powder has large specific surface area and narrow particle size distribution, and is usable preferably as a magnetic material for magnetic cards having high recording density. |
