Electrochemical machining (ECM) and electropolishing are examples of anodic dissolution used in a wide variety of applications. Proper simulations of ECM require the establishment of a so‐called gel layer of liquid metal salt, responsible for the depletion of water close to the surface such that the oxygen evolution is reduced. However, this effect is neglected in many simulation efforts, although it is significant to improve the accuracy of the machining process. Some authors consider this effect by an engineered “water‐repelling” function that depends on the local metal ion concentration. As an alternative, we discuss the theoretical description and the implementation of modified Poisson–Nernst–Planck equations taking into account expressions in which each ion has its own maximum concentration and corresponding steric limit. We investigate a basic system of water, sodium chloride, and iron ions. Simulations pending on the local metal ion concentration for current densities show that the modified model works; steric effects become important for large current densities and the formation of a resistive gel layer is responsible for the reduction of water at the electrode. We observe that the electrostatic potential resulting from space charge effects is not affected by implementing the different species sizes. Further research is needed to explore the applicability of industrial simulation tools.

中文翻译：

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高电流密度下空间对阳极溶解的空间效应的模拟研究

电化学加工（ECM）和电抛光是在各种应用中使用的阳极溶解的例子。正确的ECM模拟要求建立所谓的液态金属盐凝胶层，该层负责消耗靠近表面的水，从而减少氧气的释放。但是，尽管对提高加工过程的精度很重要，但在许多仿真工作中都忽略了这种影响。一些作者通过工程化的“拒水”功能来考虑这种效应，该功能取决于局部金属离子的浓度。作为替代方案，我们将讨论考虑到其中每个离子都有其自己的最大浓度和相应的空间极限的表达式的修正的Poisson-Nernst-Planck方程的理论描述和实现。我们研究了水，氯化钠和铁离子的基本系统。对电流密度的局部金属离子浓度进行的仿真研究表明，修改后的模型有效。空间效应对于大电流密度变得很重要，而电阻凝胶层的形成负责减少电极上的水分。我们观察到由空间电荷效应产生的静电势不受实施不同物种大小的影响。需要进行进一步的研究以探索工业仿真工具的适用性。空间效应对于大电流密度变得很重要，而电阻凝胶层的形成负责减少电极上的水分。我们观察到由空间电荷效应产生的静电势不受实施不同物种大小的影响。需要进行进一步的研究以探索工业仿真工具的适用性。空间效应对于大电流密度变得很重要，而电阻凝胶层的形成负责减少电极上的水分。我们观察到由空间电荷效应产生的静电势不受实施不同物种大小的影响。需要进行进一步的研究以探索工业仿真工具的适用性。