Simulation Of The Formation Mechanism Of AViscous Layer For The Electropolishing Process

Electropolishing (EP) is a surface finishing treatment method. The surface quality indices such as surface roughness, cleanness and corrosion resistance could be improved through this process. Because of these benefits, the electropolishing process is applied to fabricate high cleanness apparatus for semiconductor and optical pharmaceutical industries. Electropolishing is an electrochemical reaction process. The uniform and stable passive film is the key mechanism in enhancing the surface quality. However, the forming of passive film is influenced by the current distribution, fluid field and diffusion phenomena. Therefore, there are many defects such as pits, flow marks and scrape which could be found after the electropolishing process. These defects destroy the uniformity of the surface quality and induce local corrosion. The goal of this study is aimed at simulating the formation of a viscous layer and establishing numerical a model to predict its thickness and uniformity. In this study, the commercial software of FEMLAB was employed to establish a multi-physics model which contained the effects of fluidity and diffusion. The mechanism of passive film formation, the influence of fluid velocity and the thickness variation of the viscous layer were investigated through numerical simulation.