“…In order to avoid such problems and increase biocompatibility, the bioactivities of austenitic steels are subjected to various types of surface modification processes. The basic methods causing changes in surface quality include mechanical processing (grinding, polishing), laser ablation [ 8 , 9 , 10 ], thermal oxidation [ 11 ], chemical oxidation [ 12 , 13 , 14 ], micro-arc oxidation (MAO) [ 15 ], and oxidation with hydrogen peroxide [ 16 ] or electrochemical treatment [ 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. By modifying the electrolyte composition and current values in the electrochemical oxidation, we can obtain layers of different chemical compositions with different structures, e.g., amorphous, nanotube, and as a result of the application of high voltage treatment, porous layers [ 24 , 25 ].…”