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:
Dec. 04, 1990
Filed:
Feb. 23, 1990
Daidousanso Co., Ltd., Osaka, JP;
Abstract
The primary object of the invention is to clean and activate the surface of metallic works prior to such thermal treatment as nitriding, thermal spraying or dip plating by removing oxidized and other passive layers and foreign matters from the metallic work surface. The method of pretreating metallic works comprises heating a metallic work in a furnace and introducing a fluorine- or fluoride-containing gas into the furnace in that state to thereby cause destruction and elimination of the foreign matters adhering to the metallic work surface and of the oxidized layer occurring on the metallic work surface and simultaneous formation of a fluorinated layer. Just prior to the main thermal treatment, for example nitriding, the fluorinated layer is decomposed and eliminated by introducing an appropriate gas, for example H.sub.2, into the furnace. In this way, the metallic work reveals its cleaned and activated surface.