| 摘要 |
PROBLEM TO BE SOLVED: To obtain a surface treating soln. capable of imparting excellent corrosion resistance and adhesive strength of coating to light metal and light alloy materials by allowing the soln. to contain a specified amt. of permanganic acid or the salt thereof and a specified amt. of one or more kinds of a water-soluble Ti compd. and a water-soluble Zr compd. and regulating its pH to a specified range. SOLUTION: The content of permanganic acid or the salt thereof in a surface treating soln. is regulated to 0.01 to 50 g/l. The water-soluble Ti or Zr compd. can be selected from the sulfates, oxysulfates, acetate ammonium salts, fluorides or the like of Ti and Zr. The content thereof is regulated to 0.01 to 20 g/l. Furthermore, the pH of the surface treating soln. is regulated to 1.0 to 7.0. In the case the material to be treated is composed of Al or an Al alloy, the pH is regulated to 1.0 to 6.0, and in the case it is composed of Mg or an Mg alloy, the pH is regulated to 2.0 to 6.0. The surface treating soln. is brought to contact with the surface of the material to be treated under the conditions of 10 to 80 deg.C×1 to 300 sec. As the contacting method, any of immersion and spraying may be adopted.
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