模拟海洋环境下7B04铝合金电偶腐蚀预测及验证

Prediction and Verification of Galvanic Corrosion of 7B04 Aluminum Alloy Under Simulated Marine Environment

基于腐蚀电化学原理和有限元方法,建立7B04铝合金分别与CFRP、TA15钛合金、30CrMnSiA钢在模拟海洋环境下耦合时的电偶腐蚀模型,仿真得到电极表面的电偶电位和电偶电流密度分布等;实测电偶腐蚀电流并对模型的预测结果进行验证。结果表明:自腐蚀电位由高到低可依次排列为E_(CFRP)>E_(TA15)>E_(30Cr Mn Si A)>E_(7B04),耦合后7B04铝合金作为阳极而加速腐蚀;不同电偶体系的电偶电位相差不大,而电偶电流变化明显;阴/阳极面积比相同时,7B04铝合金与CFRP耦合时的电偶电流最大,即电偶效应最强,与TA15钛合金耦合时的电偶电流次之,与30CrMnSiA钢耦合时的电偶电流最弱;阴/阳极间的电偶电位和电偶电流随阴/阳极面积比的增加而线性增加;计算结果与预测结果相对误差基本在±5%以内,表明电解液中的双电极电偶腐蚀模型有较高的预测准确度。

Based on the principle of corrosion electrochemistry and the finite element method,the galvanic corrosion models for7B04 aluminum alloy with CFRP,TA15 titanium alloy and 30Cr Mn Si A steel in the simulated marine environment were established respectively.The distribution of the galvanic potential and the galvanic current density on the electrode surface were obtained.The galvanic corrosion current was measured and was used to verify the accuracy of the prediction models built at present.The corrosion potential of the four materials can be arranged from high to low as ECFRP〉ETA15〉E30CrMnSiA〉E7B04,and the 7B04 aluminum alloy is accelerated to corrode as anode after coupling.The galvanic potential of different galvanic systems has little difference but the galvanic current changes obviously.The galvanic current of the coupling between 7B04 and CFRP is the largest when the area ratio is the same.This indicates that their couple effect is the strongest.The second is between 7B04 and TA15 and the weakest is between 7B04 and 30Cr Mn Si A.The galvanic potential and the galvanic current between the cathode and anode increase linearly with the increase of the ratio of the cathode/anode area.The relative error between the calculated results and the predicted results is less than 5%,indicating that the dual electrode galvanic corrosion model in the electrolyte has a higher prediction accuracy.