Preparation and anticorrosion properties of Co-Ti-Zr composite conversion coating on 6061 aluminium alloy of the scooter profile

The traditional Cr conversion process is limited in industrial application due to environmental protection issues. The relationship between the morphology, composition and corrosion resistance of the Co-Ti-Zr composite conversion coating was systematically studied by dropping test, electrochemical test, SEM, EDX and XPS. The results show that the best conversion temperature and conversion time of CoTiZrCC is 40 ℃ and 18 min, respectively. The CoTiZrCC formed under the optimal conversion parameters is continuous and compact with the main elements of Co, Ti, Zr and Al on the surface, and its main phases are TiO2, ZrO2, Al2O3 and a small amount of fluoride. Additionally, the CoTiZrCC has lower self-corrosion current and higher film resistance, thereby greatly improving the corrosion resistance of the aluminum alloy substrate.