| 简介 |
PROBLEM TO BE SOLVED : To stably increase the coercive force of the alloy powder and to reduce the dispersion thereof by executing drying in such a manner that the powder is heated to a specifid range in an evacuated state. SOLUTION : As the raw material, rare eath oxides, iron and/or iron oxide is used, their mixture is reduced and diffused with Ca to form into an alloy block, and successively nitriding treatment is executed. Since the oxide of Ca, Ca nitride or the like used for the reaction is contained in the alloy block, these compounds are collapsed by the immersion into water, and removed by washing with water. The water-washed, alloy powder particle suspended matter is subjected to solid-liq. separation and drying. The drying is executed in such a manner that the material is heated at 100 to 240 deg.C in reduced pressure. In the case the drying is executed in the evacuated state, concretely at about 0.02 Torr vacuum, the residual water content reaches =13.8 k Oe coercive force can be obtd after the drying. Moreover, an average grain size of 1 to 5 μm is preferable for the powder, by which its coercive force can be increased. |
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