模拟海洋大气环境中丙烯酸聚氨酯涂层的失效规律

Corrosion Process of Acrylic Polyurethane Coating in Marine Atmosphere Environment

针对丙烯酸聚氨酯防腐蚀涂层在沿海大气环境使用中的问题,采用电化学阻抗谱(EIS)技术、数值分析技术,研究了40℃模拟海洋大气环境中涂层内水分的扩散过程。结果表明,涂层内水分的扩散过程的lnCc-t1/2曲线可分为两个阶段:线性增加阶段和缓慢增加阶段。计算得到第一阶段涂层中水分的扩散系数D为5.45×10-10 cm2/s。研究还发现,海洋大气环境下聚氨酯涂层老化过程大致可分为三个阶段:水渗透过程、涂层下金属腐蚀过程和涂层完全失效过程。

The degradation of wildly used acrylic polyurethane coating exposed to seawater atmosphere was investigated.The water diffusion process during coatings aging process was studied by EIS and numerical value analysis technique.The lnCc-t1/2 curves of acrylic polyurethane coating indicated that the coating capacitance（lnCc） presented two typical stages as the experimental time（t1/2） increased,the coating capacitance increased rapidly in the beginning time of test,and then tended to be a slow growth stage.According to the linear part of lnCc-t1/2 period,the water diffusion coefficient D is obtained and the value is 5.45×10-10cm2/s.It is found that the degradation process of acrylic polyurethane coating exposed to marine atmosphere can be divided into three periods,i.e.,the water permeation process,the corrosion process of metal substrate under coating and the complete failure period of coating.