| 摘要 |
PROBLEM TO BE SOLVED: To form dense and fine phosphating treated coating film on the surface of an Al material by allowing metallic fine grains to independently precipitate on the surface of an Al material and to be present as the grains in a specified grain size range and also at a specified covering rate in a state in which they are partially buried in a stage before a phosphating treating stage. SOLUTION: At the time of executing surface regulation by colloidal titanium as a part of a phosphating treating stage, metallic fine grains promoting the adhesion of colloidal titanium are forcedly adhered to the surface of an Al material to improve phosphating treatability therein. As the metal showing such characteristics, Fe, Cu, Mg or the like can be given. Furthermore, it is required that the fine grains of the metal to be used are present in such a manner that, after the precipitation and rubbing, they are independent, a part thereof lies in a state of being buried, and the maximum grain size is regulated to 0.0010 to 5μm. Then, the covering rate of the metallic fine grains is regulated to 20 to 80% by the measurement by optional 100μm<2> .
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