Chromate-Free Passive Films Made by Manganate and Waterborne Polyurethane on Galvanized Steel Sheets
In order to develop an environmental friendly passive films on galvanized steel sheet, a chromium-free passive solution based on waterborne polyurethane (WPU) and Manganate was studied. The results show that the optimized compositions in passive solution are KMnO4 6g/L, (NH2)2CS 5g/L and WPU 150g/L. The passive films were prepared by dipping steel substrates into the passive solution for 10 seconds and drying at 120 °C for 30 seconds. SEM observation shows that the film’s thickness is about 1.5 µm. XRD patterns indicates that the chromate-free passive films mainly consisted of MnO2 and K2MnO4. Anticorrosion tests indicate that the chromate-free passive films can provide an excellent barrier to corrosive agents.
Zhengyi Jiang, Xianghua Liu and Jinglong Bu
X. H. Kong et al., "Chromate-Free Passive Films Made by Manganate and Waterborne Polyurethane on Galvanized Steel Sheets", Advanced Materials Research, Vols. 154-155, pp. 292-298, 2011