Different Plasma Polishing Regimes Induced by Electrolytic Flow

This study investigates electrolyte jet processing of metals by plasma polishing, focusing on the polishing regimes and their governing flow dynamics, which result in different current density distributions and, consequently, different plasma polishing regimes. Experimental investigations performed at 350 V using a fixed-diameter electrolyte jet included localized current measurements and surface topography characterization, while finite element method (FEM) simulations were used to evaluate four plasma vapor–gas envelope (VGE) geometries. The experimental results revealed two distinct polishing regimes: a contact zone coinciding with the nozzle diameter, where the highest local cur-rent density reached 10.8 mA/mm2 and produced a maximum material removal rate of 1.17 µm/s, and a surrounding electrolyte splash zone extending to approximately twice the nozzle diameter, where the local current density progressively decreased to 2.6 mA/mm2, corresponding to a minimum material removal rate of 0.16 µm/s. Unlike previous, studies the numerical simulations showed that a constant plasma vapor–gas envelope thickness of 15.8 µm provided the closest agreement with the experimentally measured polishing profile. Based on the combined experimental and numerical results, the contact zone is interpreted as a plasma-dominated region characterized by high current density, whereas the splash zone is interpreted as a transient plasma regime in which electrochemical polishing increasingly dominates as current density decreases. This study improves the understanding of plasma electrolyte polishing (PEP), which involves both plasma-assisted and electrochemical material-removal mechanisms. The results provide guidance for im-proving surface quality and process efficiency in electrolyte-jet PEP of stainless steel.