西沙严酷海洋大气环境下紫铜和黄铜的腐蚀行为

摘要

通过现场暴晒实验，研究T2紫铜和H62黄铜在西沙海洋大气环境下分别暴晒3/4、1、2、和4 a的长周期腐蚀行为。利用SEM观察表面、截面腐蚀产物以及去除腐蚀产物后的腐蚀形貌，并分别用EDS及XRD对腐蚀产物的元素分布及相组成进行分析。结果表明，紫铜和黄铜均发生了严重的腐蚀，4 a 内其平均腐蚀速度分别为5.90和5.88μm/a；紫铜表面发生了均匀腐蚀，腐蚀产物由内层致密的Cu2O及外层的Cu2Cl(OH)3组成；黄铜发生了明显的脱锌腐蚀，腐蚀产物主要为ZnO和Zn5(OH)8Cl2∙2H2O，腐蚀产物层下的基体为20~50μm厚度不等的脱锌层。%Long period corrosion behavior of copper T2 and brass H62 after atmospheric exposure in Xisha islands for 3/4, 1, 2 and 4 a was investigated. The surface and cross­section morphologies, the elements distribution and phase compositions of corrosion products were observed by SEM, EDS and XRD, respectively. The results indicate that copper and brass undergo severe corrosion. The average corrosion rates for copper and brass in 4 a are 5.90 and 5.88 μm/a, respectively. The corrosion type of copper is uniform corrosion, a double layer structure is observed:a compact Cu2O inner layer and a porous Cu2Cl(OH)3 outer layer. Dezincification processes with zinc preferentially dissolution are evident in brass, the zinc­rich corrosion products ZnO and Zn5(OH)8Cl2∙2H2O are the predominating patina. Under the corrosion products, there exists a layer of pure copper originated from dezincification with the thickness of 20−50μm.