High anticorrosion chromate-free passive films made by Titanate and waterborne polyurethane on galvanized steel sheet

In this study, environmental friendly hybrid passive films on galvanized steel sheet were prepared from waterborne polyurethane and Titanate. The experimental results show that the optimized composition in passive solution was 30 g/L TiOSO4, 5 g/L (NH2)2CS, 10 g/L NH4F and 150 g/L WPU. The samples were dipped into passive solution for 10 s, dried at 120 °C for 15 s. Though the film's thickness is just 0.5 μm, the white rust resistance is excellent.