Patent ID: 7745008
Filing Date: 2010-06-29
Classification: C23C,Y10T

Abstract:
1. A hexavalent chromium free, corrosion resistant, trivalent chromate conversion film containing zinc, trivalent chromium, cobalt and oxalic acid and formed on zinc or zinc alloy plating layers, wherein the thickness of the film is 0.02 to less than 0.1 μm, the mass ratio of trivalent chromium to (trivalent chromium+zinc) [Cr/(Cr+Zn)] is not less than 15/100, the mass ratio of cobalt to (trivalent chromium+cobalt) [Co/(Cr+Co)] ranges from 5/100 to 40/100 and the mass ratio of the oxalic acid to (trivalent chromium+oxalic acid) [oxalic acid/(Cr+oxalic acid)] ranges from 5/100 to 50/100, and which conversion film exhibits a corrosion resistance as measured by the salt spray test (JIS-Z-2371) of 240 hours or more.