封孔电弧喷涂铝涂层在盐雾环境中的防护性能

摘要

对于采用某种有机涂料封孔处理的电弧喷涂铝涂层,采用电化学阻抗谱(EIS)、扫描电镜(SEM)和能谱(EDS)分析并结合划格试验,研究了封孔铝涂层在盐雾条件下腐蚀防护性能.结果表明,封孔电弧喷涂铝涂层很快腐蚀,但经过2 400 h盐雾加速试验(SST)后仍能对基体提供牺牲阳极保护;反应生成的铝离子可以通过封孔层孔隙渗透至面漆涂层表面并最终生成白絮状产物;根据EIS结果提出了相应的特征等效电路;SST后封孔涂层与喷涂层结合仍然良好.%Arc-spraying Al coating was prepared and porosity-sealed by a certain organic coating, and the corrosion effectiveness of the sealed Al coating was studied by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive x-ray spectra (EDS) and cross-cul test. The results showed that although the sealed arc-spraying Al coating corroded soon, it could provide effective protection for substrate even after 2 400 hours salt sloray test (SST). Al3+ produced by the sacrificial anode effect could diffuse through the pores and defects in the coating to topcoat surface, and formed flocculent products. Equivalent circuit models were proposed according to EIS results. Also, the sealing coating had better bond strength with arc-spraying Al coating after SST.