CHEMICAL TREATING LIQUID FOR METAL AND TREATING METHOD

摘要

An aqueous acid chemical treating liquid which can impart excellent corrosion resistance and coating adhesion to a metallic material without using hexavalent chromium and which is highly effective in preventing sludge generation. The chemical treating liquid contains a water-soluble trivalent-chromium compound ingredient (A), a water-soluble titanium and/or zirconium compound ingredient (B), a water-soluble nitric acid compound ingredient (C), a water-soluble aluminum compound ingredient (D), and an iron compound ingredient (E) in respective specific proportions, satisfies the relationship (CA×2+CB×4+CD×2)=CE=(CA×4+CB×7+CD×4) (wherein CA is the content of the ingredient (A) in terms of chromium metal amount; CB is the content of the ingredient (B) in terms of the total amount of titanium metal and zirconium metal; CD is the content of the ingredient (D) in terms of aluminum amount; and CE is the content of the ingredient (E) in terms of iron amount), and has a pH regulated to 2.3-5.0. This chemical treating liquid is contacted with a metallic-material surface for 1-60 seconds. This surface is then rinsed with water and dried to form a chemical conversion coating containing chromium in an amount of 0.02-1 mmol/m<SUP>2</SUP> and titanium and/or zirconium in an amount of 0.02-1 mmol/m<SUP>2</SUP> and having a thickness of 1-100 nm.