Hassle-Free Electrolytes for Electropolishing

This report investigates on eco-friendly electrolytes for electropolishing required for metallographic characterisation. Traditional acid-based electrolytes have potential health and safety hazards, both during handling and disposal. Eutectic based ionic liquids have been used from last decade to electropolish materials for aesthetics. However, they have never been evaluated to as an alternative for acid-based electrolytes aiming for metallographic preparation. In this work, we chose five different materials to electropolish with a deep eutectic solvent, ethaline. Surface roughness and electron back scattered diffraction were considered as parameters to determine electropolishing quality. The experimental results suggest ethaline can be pumped using a commercial set-up, Struers Lectropol-5 and can successfully electropolish majority of the materials, equivalent quality of acid-based electrolytes. The optimum time remains an open-ended question for further research that could be modified as function of applied voltage and temperature. We have also performed H&S and cost comparison between electrolytes. Based on our observations, we recommend ethaline can be used as a universal electrolyte for electropolishing with minimum safety concern.