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:
Apr. 18, 1989
Filed:
Mar. 23, 1988
Dimiter T Butchkov, Sofia, BG;
Yovka D Dragieva, Sofia, BG;
Zvetan K Nikolov, Sofia, BG;
Georgi G Georgiev, Sofia, BG;
Mina S Slavtcheva-Staikova, Sofia, BG;
Ivanka S Grozdanova, Sofia, BG;
VMEI Lenin, Quartal Darvenitza, Sofia, BG;
Abstract
The thermostable amorphous ferromagnetic powder containing iron, cobalt, or nickel, also comprises xylene for 0.2 to 25% by volume of the powder particles, up to 20% chrome and boron by weight, and lithium or magnesium in amounts from 0.1 to 2.0% by weight. The powder is resistant to oxidizing up to temperatures of 250.degree. C. and has a specific surface up to 160m.sup.2 /g. The method for its manufacture comprises reduction of a solution containing salts of iron, cobalt, chrome, a complexing agent, and metal salts or polyvalent alcohols by means of a reductant sodium borohydride in the presence of sodium hydroxide. The solution is protected by an organic hydrophobic substance - xylene during a period from 5 seconds to 10 minutes in the presence of a magnetic field. The device for manufacture of the thermostable amorphous ferromagnetic powder comprises a vertical reactor with a stirrer and electromagnet generating a magnetic field. The reactor is cylindrical with a movable bottom and tubes are oriented vertically to the bottom. The reaction vessel is connected by two overflow tubes to an expanded collecting vessel. Both vessels have belts for shower jet washing with water for discontinuation of the the reaction and after its cessation. The ferromagnetic powder is used in the manufacture of magnetic media recording on disks, tapes and cards, etc.