Patent ID: 7794859
Filing Date: 2010-09-14
Classification: C23C,H01F,Y10T

Abstract:
1. A rare-earth magnet comprising: a magnet body constituted of a sintered magnet containing a transition metal element and a rare earth element; and a protective film covering a surface of the magnet body; wherein the protective film includes a four-layered structure composed of a first protective layer, a second protective layer, a third protective layer and a fourth protective layer, the first protective layer having a polycrystalline structure and being adjacent to the magnet body, the second protective layer having a polycrystalline structure and being away from the magnet body, the third protective layer having a columnar-crystalline structure grown in a radial pattern which is interposed between the first protective layer and the second protective layer and being adjacent to the first protective layer, and the fourth protective layer having a columnar-crystalline structure grown in a radial pattern which is interposed between the second protective layer and the third protective layer and being adjacent to the second protective layer and the third protective layer.