腐蚀电场的力学化学耦合模型

为研究弹塑性变形对舰船腐蚀电场的影响,针对船体表面的腐蚀缺陷,利用COMSOL仿真软件中的固体力学和二次电流分布模块建立了腐蚀电场的力学化学耦合模型,使用顺序求解器分别对两个物理场进行求解,将固体力学模块仿真得到的结构应力应变耦合到电极反应的平衡电位和交换电流密度表达式,并以此作为二次电流分布模块的边界条件.研究结果表明:船体结构的变形导致了腐蚀缺陷处的应力集中,力学化学效应使得金属腐蚀电位负移,溶液中电位梯度的存在为电流流动提供了驱动力,从而形成应力腐蚀电偶,且缺陷中心为阳极而缺陷两边为阴极,当腐蚀缺陷处于弹性变形时,应力腐蚀电偶产生的腐蚀电场模值较小,当腐蚀缺陷进入塑性变形时,应力腐蚀电偶产生的腐蚀电场显著增大.

Mechanochemical coupling model of corrosion electric field

In order to study the effect of elastoplastic deformation on the corrosion electric field of ships, a mechanochemical coupling model of corrosion electric field was established by using the solid mechanics and the secondary current distribution modules in the COMSOL simulation software based on the corrosion defect of ship hull surface. Two physical fields were solved by using the sequential solver setup, and the structural stress-strain simulated by the solid mechanics module was coupled to the expressions of equilibrium potential and exchange current density of electrode reaction, which were taken as the boundary conditions of the secondary current distribution module. Results show that the deformation of the hull structure caused the stress concentration at the corrosion defect, and the metal corrosion potential shifted negatively due to the mechanochemical effect. The existence of potential gradient in solution provided driving force for the current flow, thus forming the stress corrosion couple. Moreover, the center of the defect was anode and both sides of the defect were cathodes. When the corrosion defect was elastically deformed, the modulus of corrosion electric field generated by stress corrosion couple was small, while the corrosion electric field increased significantly when the corrosion defect was plastically deformed.