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

Abstract

Abstract 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 °C 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 anti‐corrosion 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.