Patent ID: 7819989

Claim:
A method for pretreatment of a metal material containing at least one metal selected from the group consisting of aluminum, aluminum alloys, magnesium and magnesium alloys comprising the steps of: providing a treating solution for surface treatment comprising components (1) to (6), (1) 0.1 to 50 mmol/L of a compound A containing at least one metal selected from the group consisting of Hf(IV), Ti(IV) and Zr(IV) as said metal contained in compound A, (2) a fluorine-containing compound of a sufficient amount to cause etching of the surface of the aluminum, aluminum alloys, magnesium or magnesium alloys and to make fluorine exist in the treating solution in an amount of at least 7 times the molarity of the total molarity of the metal contained in compound A, (3) at least one metal ion B selected from the group consisting of Ca, Sr and Ba, (4) at least one metal ion C selected from the group consisting of Zn, Mg, Mn and Cu, (5) nitric ion, and (6) at least one compound selected from the group consisting of HClO 3 , HBrO 3 , HNO 2 , HMnO 4 , HVO 3 , H 2 WO 4 , and an oxygen acid salt thereof; contacting a surface of the metal material with the treating solution for no more than 180 seconds, the treating solution having a pH of from 3 to 6, a temperature of from 30-70° C. and free fluorine ion concentration of less than 500 ppm; etching the surface of the metal material with the treating solution; and depositing a surface-treated film layer of the metal contained in compound A of from more than 10-72 mg/m 2 .