Patent ID: 8372259
Filing Date: 2013-02-12
Classification: C25D

Abstract:
1. A method of preparing a chromium plating bath containing trivalent chromium ions and hexavalent chromium ions, comprising the steps of: (A) mixing chromic acid and an organic acid in an aqueous solution containing these acids and reducing chromic acid by the organic acid so as to prepare an aqueous solution not containing hexavalent chromium ions; (B) adding a pH adjustor to the aqueous solution not containing hexavalent chromium ions so as to adjust pH to a value of 1 to 4; and (C) farther adding chromic acid to the aqueous solution not containing hexavalent chromium ions and having undergone the pH adjustment so as to prepare an aqueous solution containing trivalent chromium ions and hexavalent chromium ions.