Coating adhesion and corrosion resistance of polyacrylic acid-zirconium composite treated aluminum.

The organic coating adhesion and corrosion resistance of polyacrylic acid-zirconium composite treated aluminum was investigated. The composite treatment solution was composed of polyacrylic acid and zirconium ammonium carbonate. Polyacrylic acid was crosslinked at its carboxyl group by zirconium compound. This reaction produced organic-inorganic composite film showing good organic coating adhesion and corrosion resistance. The most suitable composition of the composite film was obtained from the treatment solution in which weight ratio of polyacrylic acid to zirconium oxide was 1.0. The composite film of this composition showed good coating adhesion and corrosion resistance even after drawing because of its high formability. The formability of the film originated from polyacrylic acid and few defects were generated on the film by forming. Coating adhesion and corrosion resistance of the film was the same as that of unformed chromate phosphate conversion coating. After drawing or heat treatment the former was superior to the latter.