Green Approach for Electropolishing Surface Treatments of Additive Manufactured Parts: A Comprehensive Review

Over the years, the widespread diffusion of additive manufacturing, especially to produce metal objects, and the awareness of their poor surface quality due to the presence of a significant roughness, have highlighted the need to develop suitable post-processing surface treatments. In this regard, electropolishing techniques are ideal due to their high versatility, even on geometrically complex or small-sized objects, which are difficult to treat with techniques that require physical contact with a tool. On the other hand, the common use of strong and dangerous acid baths does not allow compliance with increasingly stringent sustainability criteria. For this reason, special attention is increasingly directed toward the identification of green electrolytes, based on deep eutectic or acid-free solvents, potentially capable of replacing conventional acid solutions. The choice of new environmentally sustainable and specifically appropriate solvents according to the metal alloys treated could allow a further expansion of the additive processing technologies, and therefore preserve their advantage, extending, among other things, the demand for the related finished products thanks to their superior aesthetic and functional quality.