A METHOD ABOUT INCREASING THE COERCIVITY OF A SINTERED TYPE NDFEB PERMANENT MAGNET

摘要

The invention relates to a method of increasing the coercivity of a sintered type NdFeB permanent magnet. The method comprises preparation of a diffusion source for a heavy rare earth element by adsorption of a heavy rare earth powder on at least one side of an adhesive organic film. The heavy rare earth diffusion source is applied on the surface of the sintered type NdFeB permanent magnet. Furthermore, in order to diffuse the element of heavy rare earth into the sintered type NdFeB permanent magnet along a grain boundary, a diffusion and aging treatment is performed. The method enhances coercivity while hardly reducing the remanence.