Method for producing permanent magnet based on rareearth metal having corrosion resistant film

Application Number: 00126407
Application Date: 2000.08.30
Publication Number: 1286483
Publication Date: 2001.03.07
Priority Information: 2000/8/7 JP 238587/2000; 1999/8/30 JP 243473/1999
International: H01F41/02;H01F7/02
Applicant(s) Name: Sumitomo Special Metal Co., Ltd.
Inventor(s) Name: Nishiuchi Takeji;Kikukawa Atsushi;Kikui Fumiaki
Patent Agency Code: 11038
Patent Agent: long chuangong
Abstract The present invention provides a process for producing a rare earth metal-based permanent magnet having, on its surface, a corrosion-resistant film containing inorganic fine particles having a specific average particle size and dispersed in a film phase formed from a silicon compound. In a heat treatment for forming a film by a hydrolyzing reaction and a thermally decomposing reaction of the silicon compound, followed by a polymerizing reaction, a stress is generated within the film by the shrinkage of the film. In the corrosion-resistant film formed by the producing process according to the present invention, however, such stress is dispersed by the presence of the inorganic fine particles and hence, the generation of physical defects such as cracks is inhibited.