| abstract |
PROBLEM TO BE SOLVED: To provide a chemical conversion film having good adhesion to zinc and zinc alloy plating, which is an opaque green color and has an appearance showing little or no interference color. The chemical conversion film contains (A) trivalent chromium, (B) phosphorus, and (C) at least one of monovalent to hexavalent metal ions other than trivalent chromium and aluminum. The conversion coating on zinc and zinc alloy plating not containing hexavalent chromium, and the thickness of the conversion coating is in the range of 50 to 2000 nm, and the chromium content in the conversion coating is the weight ratio. In this case, a chromium-rich zone having an average of 3% or more and a chromium content of 5% or more exists in a thickness of 20 nm or more, and the phosphorus content in the chemical conversion film is 3% or more on average. The molar ratio (P / Cr) is 1.7-5. [Selection] Figure 1 |