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:
Jun. 26, 1984
Filed:
Jul. 25, 1983
Hitachi Maxell, Ltd., Osaka, JP;
Abstract
A process for preparing ferromagnetic particles comprising metallic iron as the major component by oxidizing Fe(OH).sub.2 in an aqueous medium adjusted to a pH of not less than 11 with gaseous oxygen to produce particles of .alpha.-FeOOH, optionally followed by dehydration of the .alpha.-FeOOH particles under heating to produce particles of .alpha.-Fe.sub.2 O.sub.3, and reducing the .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 particles under heating, characterized in that (1) the aqueous medium at the oxidation step comprises at least one metal compound chosen from compounds of alkaline earth metals, zinc and aluminum and (2) the coating of a silicon compound is applied to the .alpha.-FeOOH or .alpha.-Fe.sub.2 O.sub.3 particles before the reduction step, whereby the ferromagnetic particles of metallic iron having enhanced magnetic characteristics are obtained.