| 摘要 |
PURPOSE:To prepare the titled magnetic powder preventing the sintering and aggregation of the powder particles, by converting a mixture of AO, B2O3 and Fe2O3 having specific composition to amorphous, and heat-treating the product to precipitate magnetoplumbite-type ferrite fine particles. CONSTITUTION:A mixture having a composition which falls within a region surrounded by the triangle of (a) B2O3=0, AO (A is Ba, Sr, Ca or Pb)=14.3mol%, Fe2O3 (including substituted components)=85.7mol%, (b) B2O3=0, AO= 16.7mol%, Fe2O3=83.3mol%, and (c) B2O3=50mol%, AO=50mol%, Fe2O3=0, in the triangular diagram having AO, B2O3 and Fe2O3 as three vertices, is molten by heating at about 1,350 deg.C, and quenched to obtain an amorphous material. The amorphous material is heat-treated in air at 700-850 deg.C for about 10hr to precipitate magnetoplumbite-type ferrite as fine particles. Mangetic powder suitable for the hgh density vertical magnetization recording can be obtained by this process. |
