Experimental investigation of tribo-mechanical and chemical properties of TiN PVD coating on titanium substrate for biomedical implants manufacturing

Tribological, mechanical, and chemical properties of the TiN coatings on Ti substrate were experimentally investigated for implant applications. X-ray diffraction (XRD) demonstrated that the principal crystal structure of TiN coating was (111) preferred orientation with FCC structure. Experimental evaluation was conducted at two substrate surface roughness, i.e., 0.1m and 0.4m. TiN coatings having 0.4-m substrate surface roughness and approximately 3.3-m coating thickness demonstrated optimum results of adhesion strength, hardness, coefficient of friction, wear rate, and corrosion rate in simulation body fluid (SBF). The selected TiN-coated sample exhibited maximum of 16.585GPa hardness, 238.7GPa elastic modulus, approximately 20N adhesion, and 0.088 coefficient of friction. TiN coating showed approximately 8 times more corrosion resistance and 4 times more wear resistance than the bare titanium substrate. Energy dispersive spectroscopy (EDS) analysis of the wear tracks of TiN coating in SBF showed no presence of any harmful ingredients and confirmed its biocompatibility over the usage time in SBF. TiN-coated sample with higher substrate surface roughness (0.4m) demonstrated better tribo-mechanical properties and could reduce the cost of production than the conventionally used TiN-coated Ti implants of lower substrate surface roughness (0.1m).