Influence of plasma electrolytic oxidation on mechanical characteristics of NiTi alloy

AbstractThe aim of the present work was to examine the effect of the plasma electrolytic oxidation (PEO) process on the mechanical properties of nitinol. The comparative evaluation of the microhardness and elastic modulus of the nitinol alloy and the PEO coating was carried out.The analysis of the obtained data confirmed closeness of the microhardness and elastic modulus with the respective values for nitinol layers adjacent to the coating. The reason for such a transformation on the boundary with the coating layers of nitinol could consist in the alloy amorphism as a result of the microsecond high temperature plasma influence occurring under PEO conditions and followed by sharp material cooling after attenuation of the plasma microdischarge. Unlike the thermal air oxidation (as a result, the hardness and fragility of the titanium alloy surface layers increase sharply), the changes described above facilitate increase of the mechanical and corrosion mechanical strength of the processed sample.