工业纯Sn和Sn-3Ag-0.5Cu合金在沈阳大气环境下自然暴露的初期腐蚀行为

Initial corrosion behavior of Sn and Sn-3Ag-0.5Cu alloy exposed in atmospheric environment of Shenyang

通过沈阳大气环境下的自然暴露实验研究工业纯Sn和Sn-3Ag-0.5Cu合金的早期大气腐蚀行为。采用扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)分析了表面腐蚀产物的形貌与成分。结果表明:工业纯Sn与Sn-3Ag-0.5Cu合金在沈阳工业大气环境下自然暴露后都很快发生了表面腐蚀并失泽,早期腐蚀产物疏松、龟裂并易于剥落。XPS深度分析表明:自然条件下暴露18 d后,表面腐蚀产物层厚度约为400 nm。工业大气中的悬浮物颗粒对腐蚀的形核和扩展起重要作用,Sn-3Ag-0.5Cu合金中的第二相Ag3Sn和Cu6Sn5作为阴极存在,但对大气腐蚀的加速影响不大。

The atmospheric corrosion behavior of industrial pure Sn and Sn-3Ag-0.5Cu alloy was investigated through natural exposure test in atmospheric environment of Shenyang. The morphologies and compositions of surface corrosion products were analyzed by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. The results show that, after a short exposure in atmospheric environment of Shenyang, both the industrial pure Sn and Sn-3Ag-0.5Cu alloy tarnish and form a layer of corrosion products quickly. The initial corrosion products are loose, with many cracks and easily falling off. The thickness of corrosion products layer is about 400 nm measured by XPS depth analysis. The dust （suspended particulates） in the industrial atmosphere plays an important role in the nucleation and development in corrosion process. The second phase particles Ag3Sn and Cu6Sn5 in Sn-3Ag-0.5Cu alloy act as cathode in the atmospheric corrosion, but they have little influence on the acceleration of the corrosion process.