Investigation of the structural, tribological and electrochemical properties of nitrided and boronized AISI 316l stainless steel

A biomaterial used as an implant material in the human body is expected to meet the main properties such as sufficient mechanical properties, high wear and corrosion resistance. One of the metallic biomaterials frequently used as implant material is AISI 316L stainless steel. Various thermochemical surface treatments are performed to improve the properties of AISI 316L stainless steels. In this study, plasma nitriding process at 500 ℃ temperature for 3 and 6 hours and packet (box) boronization at 950 ℃ for 2 and 6 hours was applied to AISI 316L stainless steel used as a biomaterial. Post-processing structural properties were characterized by XRD, SEM and EDS analysis, wettability properties contact angle measurements, mechanical properties microhardness measurements and surface roughness 3D profilometer. After the coating process, open circuit potential (OCP) and potentiodynamic polarization experiments were performed in artificial body fluid (SBF) prepared under laboratory conditions in order to determine the electrochemical properties. In order to determine the tribological properties of untreated and coated samples, wear tests were carried out in both dry and liquid environments. As a result of the study, it has been observed that both the applied surface treatments improve the structural, tribological and mechanical properties of AISI 316L stainless steel. According to the results, the best wear performance and hardness value were obtained from 6 hours packed boronized samples at 950 °C. As a result of the electrochemical experiments, although the corrosion resistance values of plasma nitrided samples are close compared to untreated samples, as a result, it is seen that the corrosion resistance of untreated 316L stainless steel is better than plasma nitrided samples.