Electrolyte component preference and surface integrity impact analysis for electrolytic plasma polishing of cobalt-chromium-molybdenum alloys

Abstract Cobalt-chromium-molybdenum alloys is an excellent cobalt-based alloy material used in the manufacturing of medical metal parts, which often requires a high-quality surface finish. In this paper, electrolytic plasma polishing (EPP) technology is applied to the surface treatment of cobalt-chromium-molybdenum alloy. Experiments are conducted to preference the additive components in the electrolyte to improve the surface quality after processing, and the effects of different types of complexing agents on the surface processing effect are investigated. The best polishing effect is obtained by mixing the electrolyte with ammonium sulfate and EDTA at a mass fraction of 4:1, resulting in the lowest surface roughness value of 0.0134µm and a high material removal rate of 4.935µm/min. Simultaneously, the addition of complexing agents further improves the wetting properties of the material surface. Polishing experiments are continued using the optimized electrolyte, and the surface integrity of the cobalt-chromium-molybdenum alloy is analyzed. The experimental results show that EPP can achieve a smooth and flat surface, and the surface profile curve after processing is stable and consistent. Additionally, the surface organization of the material changes, the surface layer hardness decreases and a more corrosion-resistant surface is obtained.