316L İMPLANT MALZEMESİNİN AŞINMA VE MANYETİK ÖZELLİKLERİ ÜZERİNE PLAZMA NİTRÜRLEME SICAKLIĞININ ETKİSİ

Abstract

The tribological and magnetic properties of stainless steels components are important in many biomechanical applications. Low temperature plasma nitriding is a thermochemical treatment designed so as to improve of wear resistance in stainless steels. In this work, the influence of temperature plasma nitriding on both wear and magnetic properties of 316L stainless steel was investigated by using Xray diffraction, scanning electron microscopy (SEM), pin-on-disc tribotester and VSM (Vibrating sample magnetometer). Plasma nitriding treatment of 316L stainless steel has been performed in 50%H2–50%N2 gas mixture, for treatment times of 2 h at the temperatures of 350, 400 and 450°C. The wear tests and magnetic analysis were carried out in SBF at 37 °C. XRD analyses confirm the formation of CrN, γ'-Fe4N and S-phases in the modified layer. The wear resistance increases, due to the formation of the nitrogen-supersaturated S-phase with the temperature increase, and it was improved, due to increased resistance to plastic deformation, as well as to decreased tendency towards adhesion. It was analyzed that the soft (ideal) ferromagnetic of the magnetic properties of 316L stainless steel increased with increasing treatment temperature during nitriding process. Activation of nitrogen atoms increases with increasing nitriding temperature and nitrogen atoms leads to lattice expansion and magnetic interactions are influenced because of increasing FeFe distance