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:
Oct. 12, 1999
Filed:
Jun. 20, 1997
Applicant:
Inventors:
Assignee:
TDK Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C01G / ; H01F / ;
U.S. Cl.
CPC ...
336233 ; 252 6256 ;
Abstract
A core for inductance elements is formed of a sintered body of .alpha.-ferric oxide. The core has a flexural strength of at least 6 kgf/mm.sup.2 as measured by a three-point bending method, a specific resistance of at least 10.sup.6 .OMEGA..multidot.cm, a Vickers hardness of 800 to 1,500, and an iron content of 75 to 99.9 wt %, calculated as Fe.sub.2 O.sub.3. The core is produced by granulating, and forming a ferric iron powder, and holding a formed body for sintering at 950 to 1,500.degree. C. for 5 min. to 5 hours in an atmospheric environment.