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:
Sep. 09, 1986
Filed:
Mar. 21, 1985
Yuko Sasaki, Hitachi, JP;
Katsumi Suzuki, Hitachi, JP;
Akira Minato, Hitachi, JP;
Tomio Yoshida, Takahagi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The invention is to provide zirconium or its alloy used as a material for a chemical device and a nuclear reactor etc. is surface-treated with an oxidizing acid containing an oxidizing metal ion. The oxidizing acid is at least one member or a mixture of two or more selected from the group consisting of, for example, nitric acid (HNO.sub.3), hydrogen peroxide (H.sub.2 O.sub.2), hypochlorous acid (HClO) and potassium permanganate (K.sub.2 MnO.sub.4) solution, among which nitric acid is most preferred. The oxidizing metal ion is at least one member selected from the group consisting of, for example, ruthenium, rhodium, palladium, osmium, iridium, platinum, chromium, vanadium and cerium ions. Particularly preferred treatment conditions comprise a nitric acid concentration of 14 mol/l (65%) which is close to an azeotropic concentration, a ruthenium ion concentration of at least 1.times.10.sup.-3 mol/l and a treatment temperature of a boiling temperature (120.degree. C.). The surface of zirconium or its alloy to be treated may be washed previously with an aqueous acid solution containing hydrofluoric acid. The method of inhibiting corrosion of zirconium or its alloy by surface-treating it with an oxidizing acid containing an oxidizing metal ion can be formed easily a uniform protective film on the surface thereof.