PERMANENT MAGNET

摘要

PURPOSE:To prevent the infiltration of a plating soln. to the inside of a magnet formed by a powder sintering method and to improve the mechanical strength of the magnet by thermally melting and solidifying the surface layer part of the magnet, then subjecting the surface thereof to metal plating. CONSTITUTION:Pulverized powder raw materials essentially consisting of Nd-Fe- B are mixed by a ball moll and the mixture is molded to a desired shape by using a magnetic press. The molding is subjected to sintering and aging treatments by a heat treatment device to form a sintered magnet 1. The surface layer part of the magnet is melted and quickly cooled by using a CO2 laser to form a thermally melted and solidified layer 2 to seal the void parts among the crystal grains. The surface is further subjected to electroless plating so that the metallic plating layer 3 is coated. The permanent magnet which is improved in the corrosion resistance and is prevented of the degradation of the mechanical strength and magnetic characteristics during the long-term use is thus obtd.