Nanomechanical and tribological characterization of TiO2 and TiN coatings deposited on 316L stainless steel for biomedical applications

In this work, we have developed titanium-based biocompatible nano-sized layers (TiN and TiO2) on 316L stainless steel (SS), by CAE-PVD (Cathodic Arc Evaporation), which presents an efficient process for the synthesis of coatings with controlled properties. We focused our study on a mechanical and tribological characterization of coatings by indentation tests and scratch tests. The results obtained show a dense and uniform morphology coupled with important mechanical and interfacial properties. The TiN and TiO2 coatings showed a hardness of between 5.9 GPa and 8.23 GPa. Measurement of adhesion by scratch tests showed that both coatings have a slightly different adhesion quality. The TiN and TiO2 developed layers showed critical cohesion loads of between 1.8 N and 3.3 N with a critical adhesion load of 13.1 N. Tribological properties were investigated, using a constant multi-pass Scratch test, allowed to examine the coefficient of friction and to determine the rate of energetic wear. The friction coefficients of the two layers studied are of the same order of magnitude (0.1), but we can say that the resistance to friction varies from one layer to another. The specific energy of wear was between 3.09 x 10(-5) J/mu m(3) and 8.36 x 10(-5) J/mu m(3), and it did not change after immersion of the TiN layer for 48 h in a 3% NaCl solution. The TiN thin film, which is known for its biocompatibility and biological performance, has shown mechanical and tribological properties that allows it to be used in hip and knee implants.