Chromate-Free Passive Films Made by Manganate and Waterborne Polyurethane on Galvanized Steel Sheets

Abstract:

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.

• Periodical: Advanced Materials Research (Volumes 154-155)
• Pages: 292-298
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.154-155.292
• Online since: October 2010
• Authors: Xiang Hua Kong, Hui Yang, Ya Xuan Liu, Wan Heng Lu, Jing Guo, Shan Shan Liu
• Keywords: Galvanized Steel Sheet, KMnO₄, Passive Films, Waterborne Poly Urethane

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