| abstract |
An aluminum-containing metal material for, for example, a heat-exchanger for motorcars is surface-treated by chemically etching an Al-containing metal material surface, forming a first protective layer on the etched surface by a chemical conversion treatment with an aqueous solution of Zr phosphate or Ti phosphate, and coating the first protective layer with a second protective layer containing a hydrophilic resin including non-cross-linked hydrophilic functional groups and at least partially cross-linked reactive functional groups different from the hydrophilic functional groups, to impart high hydrophilicity and resistance to odor generation and corrosion to the aluminum-containing metal material surface. |