The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 21, 2009
Filed:
Jan. 27, 2006
Hajime Nakamura, Echizen, JP;
Koichi Hirota, Echizen, JP;
Masanobu Shimao, Echizen, JP;
Takehisa Minowa, Echizen, JP;
Hajime Nakamura, Echizen, JP;
Koichi Hirota, Echizen, JP;
Masanobu Shimao, Echizen, JP;
Takehisa Minowa, Echizen, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A functionally graded rare earth permanent magnet is in the form of a sintered magnet body having a composition RRTAFOMwherein the concentration of R/(R+R) contained in grain boundaries surrounding primary phase grains of (R,R)TA tetragonal system within the sintered magnet body is on the average higher than the concentration of R/(R+R) contained in the primary phase grains, Ris distributed such that its concentration increases on the average from the center toward the surface of the magnet body, the oxyfluoride of (R,R) is present at grain boundaries in a grain boundary region that extends from the magnet body surface to a depth of at least 20 μm, and the magnet body includes a surface layer having a higher coercive force than in the interior. The invention provides permanent magnets having improved heat resistance.