Chemical conversion solution for metal structure and surface treating method

Abstract

The present invention provides a chemical conversion solution and the surface treating method for realizing high corrosion resistance and high coating adhesion of the metal surface, as well as high throwing power during electrodeposition, and generating no sludge. A chemical conversion solution comprising (A) at least one compound selected from water-soluble germanium compound, water-soluble tin compound, and water-soluble copper compound, (B) at least one compound selected from water-soluble titanium compound and water-soluble zirconium compound, (C) at least one water-soluble nitrate compound, (D) at least one compound selected from water-soluble aluminum compound and water-soluble magnesium compound, (E) at least one water-soluble zinc compound, and (F) at least one fluorine compound, and, the coating process for the metal structure.

1 . A chemical conversion solution for a metal structure comprising
 (A) at least one compound selected from water-soluble germanium compound, water-soluble tin compound, and water-soluble copper compound   (B) at least one compound selected from water-soluble titanium compound and water-soluble zirconium compound,   (C) at least one water-soluble nitrate compound,   (D) at least one compound selected from water-soluble aluminum compound and water-soluble magnesium compound,   (E) at least one water-soluble zinc compound, and   (F) at least one fluorine compound, wherein   content (C A ) of at least one member selected from germanium, tin, and copper is 0.05 mmol/L to 10 mmol/L,   content (C B ) of titanium and/or zirconium is 0.1 mmol/L to 10 mmol/L,   content (C C ) of nitrate radical in the water-soluble nitrate compound (C) is 3 mmol/L to 300 mmol/L,   content (C D ) of aluminum and/or magnesium is 1 mmol/L to 200 mmol/L,   content (C E ) of zinc is 0.2 mmol/L to 20 mmol/L,   content (C F ) of fluorine in the fluorine compound (F) satisfies the following equations:
     C   F  (minimum value)= C   A ×2 +C   B ×4 +C   D ×2
 
     C   F  (maximum value)= C   A ×4 +C   B ×7 +C   D ×4, and
 
   pH of the chemical conversion solution has been adjusted to the range of 2.5 to 4.4.   
     
     
         2 - 15 . (canceled)