JPH0644525B

PURPOSE:To form a corrosion-proof thin film, having excellent adhesive property and corrosion-proof property, on the surface of a permanent magnet material in uniform thickness by a method wherein a corrosion-proof thin film layer is formed on the surface of a permanent magnet body, having the main phase consisting of tetragonal crystal, by an ion vapor-deposition thin film forming method. CONSTITUTION:The fine powder, in the composition of Nd 15, Dy 1.5, B 8 and Fe 75.5atom%, is placed in a metal mold, the fine powder is oriented in a magnetic field, and a molded body is formed by molding. The molded body is heat-treated, and a permanent magnet is manufactured. A test piece is cut out from the permanent magnet obtained, the Ti thin piece of coating material is evaporated by arc discharge under vacuum in a vacuum container containing the test piece, N2 gas is formed into accelarated N2 gas ions, Ti vapor and N2 gas ions are made to irradiate, and a Ti thin film is formed on the surface of the test piece. As a result, a corrosion-proof thin film layer, having the prescribed thickness and excellent uniformity, can be obtained, and the oxidization of the permanent magnet can completely be prevented.