Improvement in Austenitic Stainless Steel Implant via Dual-Layer Coating of TaN-DLC Using Sputtering and PACVD Methods

In order to improve the properties and performance of SS316L implants in the current study, their surface was coated using two methods of sputtering and Plasma-Assisted Chemical Vapor Deposition (PACVD). To this end, TaN and Diamond-Like Carbon (DLC) layers were applied using sputtering and PACVD methods, respectively. Structural examinations by Field-Emission Scanning Electron Microscopy (FESEM) showed that the TaN layer was formed in a compact and quasi-spherical morphology. The final DLC layer was also formed in a compact and spherical morphology. Raman spectroscopic results showed that the D and G peaks with suitable heights were at 1356 cm-1 and 1588 cm-1, respectively, indicating the successful DLC formation. Atomic Force Microscopy (AFM) images indicated that the grain size was in the range of 20-35 nanometers, and the presence of very fine DLC grains contributed to reducing the surface roughness to Ra=1.02 µm, indicating a 67.5% reduction. Cell adhesion test results up to 48 hours confirmed the better performance of DLC than that of TaN. Thus, the TaN-DLC two-layer coating is introduced as a new coating that can be used to improve the performance of implants.