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. 17, 1981
Filed:
Apr. 03, 1979
Atushi Takedoi, Hiroshima, JP;
Nanao Horiishi, Hiroshima, JP;
Goro Matsui, Hiroshima, JP;
Koji Toda, Hiroshima, JP;
Toda Kogyo Corp., Hiroshima, JP;
Abstract
Stabilization treatment of acicular ferromagnetic iron or iron-alloy fine particles against the oxidation thereof comprises the steps of (a) suspending acicular ferromagnetic iron or iron-alloy particles obtained by the reduction of acicular iron oxide which may contain Co or Ni in an aqueous alkaline solution having 0.01 to 18-N of hydroxyl ion concentration at a temperature of 5.degree. to 70.degree. C. while stirring the suspension in a non-oxidative atmosphere therethrough and thereby controlling the dissolution of ferrous ion from the surface of the acicular particles therein, (b) oxidizing the surface of the acicular particles in the resultant suspension by introducing an oxygen containing gas therein at a temperature of 60.degree. to 100.degree. C. to form dense and thin magnetite film on the surface of the acicular particles; and (c) drying the resultant particles in air at a temperature below 100.degree. C.