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:
Mar. 04, 2003
Filed:
Jan. 24, 2000
Misao Namikawa, Kawasaki, JP;
Yoshikazu Takada, Kawasaki, JP;
Shoji Kasai, Kawasaki, JP;
Hironori Ninomiya, Machida, JP;
Tsunehiro Yamaji, Kawasaki, JP;
Tatsuhiko Hiratani, Fukuyama, JP;
NKK Corporation, Tokyo, JP;
Abstract
A silicon steel sheet having low iron loss of high frequency has a surface layer of the steel sheet which has Si concentration higher than Si concentration of a center portion of the steel sheet. Si concentration of sheet thickness center is 3.4 wt. % or more and Si concentration of the surface layer of the steel sheet is 5 wt. % or more. Si concentration in a surface layer portion is 5 to 8 wt. %. The production method comprises siliconizing treatment and diffusing treatment. Velocity of siliconizing and diffusing are controlled, and Si concentration distribution in the sheet thickness direction of the steel sheet is controlled.