Plasma electrolytic polishing (PEP) is an environment-friendly alternative to the conventional electrochemical polishing (EP), giving optimal surface properties and improved corrosion resistance with minimum energy and time consumption, which leads to both economic and environmental benefits. This paper is focused on the corrosion behavior of PEP treated AISI 316L stainless steel widely used as a biomaterial. Corrosion resistance of plasma electrolytic polished surfaces without/with chemical pretreatment (acid cleaning) is evaluated and compared with original non-treated (as received) surfaces by three independent test methods: electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and exposure immersion test. All corrosion tests are carried out in the 0.9 wt.% NaCl solution at a temperature of 37 ± 0.5 °C to simulate the internal environment of a human body. The quality of tested surfaces is also characterized by optical microscopy and by the surface roughness parameters. The results obtained indicated high corrosion resistance of PEP treated surfaces also without chemical pretreatment, which increases the ecological benefits of PEP technology.

The technology of plasma polishing in electrolyte is considered as environmental friendly alternative to the common electrochemical polishing process. The solutions of the electrolyte use no acids or toxicants, but the environmental safe, low concentrated aqueous solutions of various inorganic salts are used instead. The dependence of the gloss level of the treated surface upon the electrolyte concentration as well as upon the voltage is examined in this paper. The specimens of stainless steel were used for plasma polishing in ammonium sulphate based electrolyte. The influence of the voltage on the overall properties of the process is discussed, as well.