中文摘要：

丝状腐蚀多发生于飞机蒙皮边缘及紧固件周围涂层破损处,是一类特殊的缝隙腐蚀。基于NernstPlanck方程,采用有限元法开展了丝状腐蚀头部缝隙的仿真研究。结果表明,缝隙中的p H值随时间先下降而后上升,最后稳定在5.4-6.0之间的酸性条件下;选择有O2存在且溶液p H值为6的极化曲线作为边界条件较为合适;缝隙内铝合金界面主要发生Al的阳极氧化反应;缝隙口溶液电势低于缝隙底部的溶液电势,缝隙口附近铝合金的腐蚀速率更快;固态腐蚀产物Al（OH）2Cl多集中于缝隙底部,Al（OH）2Cl浓度随反应时间的延长而升高;电位对丝状腐蚀的扩展影响很大,电位升高,缝隙内铝合金的腐蚀加剧,Al（OH）2Cl的生成速率加快;电位提高20 m V,缝隙底部的Al（OH）2Cl浓度升高5倍,极大地加速了丝状腐蚀的扩展。

英文摘要：

Filiform corrosion often occurs at the damaged coating around the fastener and the aircraft skin edge,which is a special kind of crevice corrosion. The crevice in the head of filiform corrosion is simulated by finite element method based on Nernst-Planck equation. The results indicate that the p H value in the crevice initially drops and then rises over time,and finally stabilizes at about 5. 4 - 6. 0 under acidic conditions. The polarization curve measured in the solution with O2（ p H = 6） is suitable for the boundary condition. The aluminum alloy interface in the crevice mainly involves anodic oxidation reaction of Al.The electrolyte potential in the crevice mouth is lower than that in the bottom of the crevice,the corrosion rate of aluminum alloy near the crevice mouth is much faster. Solid corrosion product Al（ OH）2Cl concentrates mostly in the bottom of the crevice,and the concentration of Al（ OH）2Cl increases over the reaction time. The potential has great influence on the expansion of filiform corrosion,the corrosion rate of aluminum alloy and the formation rate of Al（ OH）2Cl in the crevice exacerbate with the rising of potential. When the potential rises by 20 m V,the Al（ OH）2Cl concentration at the bottom of the crevice rises 5 times,which greatly accelerates the expansion of the filiform corrosion.