Nanostructured multilayer CAE-PVD coatings based on transition metal nitrides on Ti6Al4V alloy for biomedical applications

Titanium alloys possess poor resistance to friction and this adversely affects the corrosion behavior and osseointegration of the implants made from these alloys. Nanostructured PVD coatings with biocompatibility, anti-wear and anti-corrosion characteristics have attracted much attention in biomedical applications. In this study, 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 and, FTIR. The corrosion performance of the coatings was studied using PDP and EIS assessments in SBF solution. 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. The corrosion assessments revealed that the CrN/ZrN multilayer coating exhibited the best corrosion resistance due to its smoother surface and more dense structure in addition to its specific architecture. The ZrN single layer and CrN/ZrN multilayer coatings showed a better hydroxyapatite precipitation; however, all surfaces had satisfactory bioactivity. In all, this study showed that CrN/ZrN nanostructured multilayer thin film is potentially suitable candidate for orthopedic and dental implants.