Application of Ti/Zr Chemical Conversion System on Several Aluminum Alloys and Galvanized Steel

The primer coating technology applicable to a variety of aluminum alloys and steel materials has become a key requirement for the manufacturing of lightweight body for new energy vehicles. In this paper, a study on chemical conversion of metal surfaces based on the titanium/zirconium composite system was carried out on 6061 and 7075 aluminum alloys and galvanized steel. The effects of H2TiF6 concentration, H2ZrF6 concentration and process parameters on the corrosion resistance of the coatings formed on the surfaces of the three metals were investigated through copper sulfate spot experiments, and the corrosion resistance of the coatings was verified by electrochemical testing. Moreover, the scanning electron microscope and the energy spectrometer were employed to observe and analyze the surface morphology and element composition of the conversion coatings. Results showed that after a conversion treatment under the conditions that the H2TiF6 concentration was 1.60～2.00 mL/L, the H2ZrF6 concentration was 0.80～1