Ageing resistance and corrosion resistance of silicone-epoxy and polyurethane topcoats used in sea splash zone

摘要

The silicone-epoxy and polyurethane topcoats applied in a simulated sea splash environment were studied according to ISO20340 standard, and their properties were analyzed by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectrum (EIS). Glass transition temperature (T_g) of silicone-epoxy polymer is 7.7℃ higher than that of polyurethane polymer. Measurement of gloss and color difference demonstrates that anti-ageing property of silicone-epoxy topcoat is better than that of polyurethane topcoat. It is known from SEM and XPS analysis that silicone-epoxy topcoat can retain the good morphological structure and ageing resistance after accelerated cycle ageing test. The results from EIS analysis indicate that the silicone-epoxy topcoat has good anticorrosion properties. Measurement of contact angles indicates that surface tension of silicone-epoxy topcoat is smaller than that of polyurethane topcoat before and after corrosion test.