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:
Feb. 02, 1993
Filed:
Jun. 04, 1991
Toshio Ueda, Tokyo, JP;
Yuichi Sato, Tokyo, JP;
Masayasu Senda, Tokyo, JP;
Seiji Isoyama, Tokyo, JP;
Seiichi Hisano, Tokyo, JP;
Dowa Mining Co., Ltd., Tokyo, JP;
Abstract
A process for producing a permanent magnet alloy based on a R--Fe--B--C system wherein R is at least one of the rare earth elements including Y, comprising the steps of preparing a molten crude alloy, producing a powder directly therefrom or after casting it into an alloy ingot and then grinding it into the powder, compacting the thus obtained powder and sintering the compacted product, the ingot or powder of the alloy before being sent to the compacting step being subjected to a heat treatment which is carried out at a temperature of 500.degree.-1,100.degree. C. for a period of 0.5 hour or more so as to produce a permanent magnet alloy based on an a R--Fe--B--C system whose individual magnetic crystal grains are covered with an oxidation-resistant protective film which has a C content higher than that of the individual crystal grains.