2A12-T4铝合金在盐雾环境下的腐蚀行为与腐蚀机理研究

Corrosion Behavior of 2A12-T4 Al-alloy in Salt-spray Environment

采用失重法、扫描电镜(SEM)、X射线衍射仪(XRD)和电化学技术研究了2A12-T4铝合金在盐雾环境下的腐蚀规律及机理。结果表明:2A12-T4铝合金的腐蚀失重量与腐蚀时间符合幂指数函数规律。腐蚀初期,在Cl-作用下2A12-T4合金发生点蚀,随后点蚀发展为全面腐蚀,电化学腐蚀产生大量Al(OH)3导致疏松腐蚀产物层增厚;腐蚀中、后期,外层腐蚀产物发生脱落,剩余致密堆叠的腐蚀产物层。电化学测试表明,随着腐蚀时间的延长,2A12-T4合金的自腐蚀电流密度先减小后增大再减小,容抗弧先收缩后扩大,最后略有收缩。

The corrosion behavior of 2A12- T4 Al- alloy in salt- spray environment was studied by means of mass loss method, electrochemical test, scanning electron microscope（SEM） and X- ray diffraction（XRD）. The results show that the relationship between the corrosion induced mass loss and corrosion time was in accordance with power rule. At the initial corrosion stage, pitting corrosion occurred under the action of Cl-, then pitting corrosion turned to be overall corrosion, and the scale of corrosion products composed of Al（OH）3was loose and thickened with time. During the middle and later corrosion stages, the outer portion of corrosion product spalled off, while the residual portion of corrosion product scale became compact. With the increasing corrosion time, Icorrdecreased firstly, then increased and finally decreased again. In the meantime, capacitive reactance arc shrunk firstly, then expanded, and finally shrunk slightly.