Trivalent chromium passivation based on zincate plating

The electrochemistry behavior,surface microstructure and forming process of trivalent chromium passivation film were studied by electrochemical methods,scanning electron microscopy and X-ray photoelectron spectroscopy.The trivalent chromium passivation film based on zincate plating obtained has compact structure with no obvious crack,and excellent anticorrosion performance.Different compositions are detected from the surface to inner film,the surface mainly contains Cr2O3-Cr(OH)3-ZnO compound,the inner(10?30 nm to surface) composes of Cr2O3-ZnO-Zn.The forming process of passivation film possibly consists of four steps which are zinc dissolution,basic area appearance,gelatiniform film forming and converting to passivation film.