The poor resistance of Titanium alloys to friction, wear and scratch adversely affects their performance as orthopedic and dental implants. Nanostructured nitride-based PVD coatings have attracted much attention in biomedical applications for several decades because of their good biocompatibility, bioactivity, high hardness, anti-wear and anti-corrosion characteristics. In this study, the same thickness of TiN and ZrN single layer and CrN/TiN and CrN/ZrN nanostructured multilayer thin films were applied on a Ti6Al4V substrate by means of cathodic arc PVD technique. The physical-chemical characterization of the coatings was conducted using FE-SEM, EDS, and XRD analyses. Their surface topography and wettability were measured. In addition, the hardness and adhesion strength were eva‎luated by means of Knoop microhardness and scratch tests, respectively. Also, the apatite-forming ability of the coatings was investigated through SEM, EDS, FTIR, ICP and XRD through a 14 days immersion period in SBF. The corrosion performance of the coatings was studied using PDP and EIS assessments in SBF solution during 28 days immersion period. The surface chemical composition analysis, via X-ray Photoelectron Spectroscopy (XPS) after a 30-day exposure to Phosphate-Buffered Saline (PBS), was studied. According to the findings, the multilayer coatings have higher hardness and scratch resistance than single layers. The coating delamination tacked place in Lc equal 39.6 (N) and 39.3 (N) for CrN/TiN and CrN/ZrN coatings, respectively. While these amount were 22.1 and 23.9 N for TiN and ZrN single-layer respectively. As a results of bioactivity assessment all surfaces could be categorize as bioactive materials why so their surface was completely covered with hydroxyapatite deposits after 14 days of immersion. eva‎luation of corrosion resistance of coatings showed that, the surface morphology and microstructure of coatings are 2 effective parameters in their corrosion resistance. For this reason the highest amount of corrosion resistance during 28 days immersion period was obtained for CrN/ZrN coatings with the polarization resistance (Rp) equal to2.02×10^6 〖Ω.cm〗^2. Direct cytocompatibility assessments were conducted with bone marrow mesenchymal stem cells (hMSC). No significant differences in metabolic activity and cell morphology were evidenced between the single-layer and multilayer coatings. The Antibacterial efficacy tests against Methicillin-resistant Staphylococcus aureus were assessed. The results demonstrated a significant reduction in bacterial metabolic activity by 44% and 56% for CrN/TiN and CrN/ZrN, respectively, compared to the uncoated control. Furthermore, bacterial colony-forming unit (CFU) counts indicated a 2 log and 1 log reduction for CrN/TiN and CrN/ZrN, respectively, relative to the control.

مسعود عطاپور , فخرالدين اشرفي زاده

حسن علم خواه

مهران نحوي , رحمت اله عمادي , بهروز موحدي