INVESTIGATION OF BLACK TARNISHED FILM ON ZINC PLATED SURFACE
电镀锌层表面黑变膜的研究

The composition and structure of black tarnished film on zinc plated surface were investigated by means of SEM,EDX,XRD and XPS. It was found that black tarnished film is a corrosion products formed on zinc plated surface, and impurity Pb accelerates electrochemical corrosion process of zinc by depolarization. This film possibly composed of ZnO, Zn 5(CO 3) 2(OH) 6,and trace PbO. The results of XPS analyses showed that Zn exists as stoichimetric compound ZnO in the surface layer of the film, while as non stoichimetric compound ZnO 1 X in the inner layer of the film. It was also found that the color of black tarnished film was induced by light interference effect to the film.