Mechanism and technological opportunity of plasma electrolytic polishing of metals and alloys surfaces

Plasma electrolytic polishing is a relatively new method which is successfully applied for finishing metals and alloys due to several advantages. These include the high quality of the polished surface, the use of environmentally friendly and inexpensive aqueous solutions, the high processing speed, etc. To date, electrolyte compositions and processing regimes for a wide class of products made from various metals and alloys have been developed, as well as original technical solutions for implementing the process and creating equipment. All information obtained by many research groups needs analysis and generalization. This review examines the physical and chemical aspects of plasma electrolytic polishing, its place among other plasma electrolytic technologies as well as the conditions and results of its practical use. The action of electric discharges in system and electrochemical dissolution on the workpiece in increasing the surface roughness remains debatable. There are hypotheses regarding important aspects of the process which do not always have experimental evidence. Attention is also paid to the influence of the main factors of plasma electrolytic polishing on the achieved roughness and removal rate of the treated material. A separate section is devoted to the problem of process control.