铝合金阳极氧化层在江津污染大气环境中暴露腐蚀行为研究

Atmospheric Corrosion of Anodized Pure Al1060,Al-alloys 2A12 and 7A04 Exposed to Polluted Atmospheric Environment at Jiangjin Region

采用扫描电镜、能谱和X射线衍射仪以及腐蚀失重等分析测试方法研究了1060纯Al、2A12和7A04铝合金表面阳极氧化膜层在江津工业大气环境中的暴晒腐蚀行为。结果表明,1060纯Al、2A12和7A04铝合金阳极氧化膜层失重与暴露时间的关系符合幂函数规律;随腐蚀时间的延长,腐蚀产物不断增多,失重增大。3种铝材腐蚀严重程度顺序由大到小依次为:2A12铝合金>7A04铝合金>1060纯Al。腐蚀产物呈团状和块状形貌,主要由Al2O3、Al(OH)3和硫酸铝水合物组成。3种铝材除去表面腐蚀产物的阳极氧化膜层损伤和腐蚀坑数量差别明显,腐蚀机制为Al2O3在酸性介质中的溶解。

The atmospheric corrosion behavior of anodized pure Al 1060 as well as Al-alloys 2A12 and 7A04 exposed for 24 months in atmosphere with pollutants at Jiangjin region was investigated by mass loss method,scanning electron microscope（SEM）,energy dispersive X-ray detector（EDS） and Xray diffractometer（XRD）.The results show that the relation of mass loss versus time（h） accords with power function law as C=Atn.In other words,the corrosion product is increasing with testing time.The order of corrosion severity of the tested materials can be ranked as the following order 2A12 alloy〉7A04 alloy〉1060.The corrosion products show agglomerate structure composited of Al2O3,Al（OH）3 and aluminum sulfate hydrate.After removing the surface corrosion products,clear difference in the damage manner and the quantity of corrosion pits can be observed for the three anodic oxidation films.The corrosion mechanism may be ascribed to the dissolution of alumina in certain acidic medium.