Electropolishing(EP) is a surface treatment process which improves the surface roughness and enhances the surface quality by electrochemical reactions. The system is composed of an anode, a cathode, a power supply and viscous electrolyte. From the electrochemical reactions, the anodic metallic dissolution will leave off the surface and formed a viscous layer to enhance the surface quality, especially in stainless steels. It improves for the chrome to iron ratio and reduces the surface activity to avoid the surface corrosion from environment. From the anodic dissolution, the water may also be electrolyzed to form the hydrogen and oxygen bubbles on the anode and cathode plates. The viscous electrolyte causes the bubbles hard to escape from the gap between electrodes resulting ineffective natural convection and no idea about where and when of the viscous layer would be destroyed. So it is hard to predict the EP effects under natural convection during the EP process. It decreases the process stability as well as specimen surface quality. In this study, two methods of electrolyte agitation were employed to study their effects on electropolishing. The first method was by mechanical electrode movement. The second method was by ultrasonic agitation. The forced convection, generated by electrode movement and ultrasound, will accelerate the speed of bubbles leaving, breaking up from the surface and refreshing the electrolyte between electrodes. Thus, it may accomplish the goal of maintaining the stability of reaction environment during the EP process. The materials of both anode and cathode were SS316L stainless steel. The compositions and temperature of the electrolyte remained the same in each experiment. The control variables of experiments were electrode gap, rotational speed, amplitude of electrode movement and polishing time in mechanical agitation experiments. Frequency and amplitude of ultrasound were the control variables in the ultrasound experiment. The surface quality indicators were surface roughness and qualitative microscopic evaluation of surface morphology. According to the variations of surface quality indicators, the parametric effects on EP process will be analyzed. And the effectiveness of electrolytic agitation method on the surface quality and process stability were evaluated.
- Manufacturing Engineering Division and Materials Handling Engineering Division
Evaluation of Electrode Agitation Effects on Electropolishing Process
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Lee, S, & Lai, J. "Evaluation of Electrode Agitation Effects on Electropolishing Process." Proceedings of the ASME 2004 International Mechanical Engineering Congress and Exposition. Manufacturing Engineering and Materials Handling Engineering. Anaheim, California, USA. November 13–19, 2004. pp. 673-678. ASME. https://doi.org/10.1115/IMECE2004-60152
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