| 摘要 |
PURPOSE:To improve magnetic properties such as coercive force and squareness ratio with reduced contamination such as oxidation and corrosion or grain boundary damage by obtaining a ribbon-shaped or flaked alloy thin band by subjecting a molten alloy arranged to a predetermined chemical composition to a liquid quenching, and then applying a hydrogen embrittlement treatment. CONSTITUTION:Liquid bath of a permanent magnet alloy whose composition is Nd15Fe77B6 is prepared in a radio frequency melting furnace, such liquid bath of alloy is made into a thin band by means of a liquid quenching in which it is made to flow down from a nozzle onto a single roll surface rotating at a high speed in an argon atmosphere, a magnetic powder being obtained by a hydrogen embrittlement treatment and a mechanical granulation treatment. The hydrogen embrittlement treatment is made by storing the alloy thin band in a treatment chamber 1, evaporating the chamber by a rotary pump 2, replacing it by Ar gas and then changing to a hydrogen gas source to obtain a hydrogen gas atmosphere (H2 100%) whose pressure is 2kg/cm<2>. After 24hours, the treatment chamber 1 is evaporated and maintained for 1hour. Hydrogen gas is introduced again in the treatment chamber 1 to obtain the hydrogen gas atmosphere of 2kg/cm<2>, such atmosphere being maintained for 24hours, evaporated and then maintained for 1hour. |
