Evolution of model roughness on quasi-pure aluminum during plasma electrolytic polishing

Abstract

The present paper studies the material removal evolution, during Plasma Electrolytic Polishing (PeP), on model roughnesses prepared on 1050 aluminum alloy (AA), i.e. a quasi-pure aluminum, used as a model substrate.The results obtained in this study confirm the significance of the applied voltage on aluminum removal. In particular, the minimal voltage to be applied to generate the plasma is seen to be above 230 V. Meanwhile, at a higher voltage of 300 V, high quality polishing is obtained. Using this technique, rolling streaks are eliminated rapidly without the workpiece's geometry being adversely affected.Finally, roughness evolution was accurately studied on a series of samples with various well-defined levels of model roughness generated by microindentation. The study shows that only a few minutes of processing are needed to obtain a significant reduction in roughness, even representing up to 70%. Results show also that roughness valleys do not undergo material removal at all as long as peak to valley height remains high enough. As the process goes on, roughness (i.e. mainly peaks) is reduced and valleys become submitted to material removal as well.