| 摘要 |
PURPOSE:To eliminate the deterioration of magnetic characteristics, and to lengthen life by forming a film having airtightness on a base body for a permanent magnet. CONSTITUTION:A base body for a permanent magnet is composed by combining an element, such as Sm, Ce, Y, La, Pr and Co and elements of two kinds selected from a group of Cu, Fe, Zr, Mn, Nb or Hf. Powder having such a composition is molded to a predetermined shape in a magnetic field through melting, casting and grinding processes, and sintered, thus obtaining the base body for the permanent magnet. Since the base body of the sintered magnet has a property easy to be oxidized as a formation on the surface of an oxide layer in approximately 100mum when it is left in air for 100hr at 200 deg.C, a film having airtightness is formed on the surface of the base body, and the base body is encapsulated. The film may be constituted by a metallic film through a method, such as wet type plating vacuum evaporation, sputtering or the like. The adaption of a ferromagnetic metal is the most effective from a viewpoint of preventing the lowering of magnetic characteristics at that time. An alloy such as a Co-Ni-Cr one can be applied to the adoption of the metal. |
