【摘要】 利用电化学阻抗谱(EIS)、紫外老化、扫描电镜(SEM)和红外光谱(FTIR)等方法研究了铝合金板表面涂覆的聚氨酯面漆的耐蚀性能和老化机制。结果表明，在3.5wt.%NaCl溶液中浸泡240 h后，聚氨酯面漆发生了后固化现象。在浸泡384～1560 h期间，聚氨酯面漆/铝合金体系界面发生微腐蚀。在浸泡1920～2160 h期间，铝合金基材表面产生了腐蚀产物膜。聚氨酯面漆在紫外老化实验中，表面逐渐产生孔洞变得疏松并发生剥落、光泽度逐渐下降、失光率增加以及色差先增加后趋于稳定，老化前期以可见光降解为主，老化后期以紫外光降解为主。更多还原

【Abstract】 The corrosion resistance and aging mechanism of polyurethane topcoat on Al-alloy plates used for high-speed train were studied by electrochemical impedance spectroscopy(EIS), ultraviolet aging, scanning electron microscopy(SEM) and Fourier transform infrared spectroscopy(FTIR). The results showed that the polyurethane topcoat presented post-curing phenomenon after immersing in 3.5wt.%NaCl solution for 240 h. The topcoat/Al-alloy interface was slightly corroded within the period of 384-1560 h,and the corrosion product film was formed on the surface of Al-alloy substrate within 1920-2160 h. During the ultraviolet(UV) aging test, holes gradually emerged on the surface of polyurethane topcoat, which then became loose and spalling, meanwhile its glossiness gradually decreased with increasing reduction of glossiness, as well as its color difference increased and then tended to be stable. It follows that the visible light degradation was the main degradation in the early stage of aging, and UV degradation was the main degradation in the late stage of aging.更多还原