Ceramic tantalum oxide thin film coating to enhance the corrosion and wear characteristics of Ti6Al4V alloy

In this research, an attempt is made to study the corrosion and wear behavior of TaO2 thin film coating deposited onto Ti6Al4V alloy with the highest adhesion (was achieved in the author's previous experiments using Taguchi statistical method) which leads to increase corrosion resistance, decrease debris generation and improve durability. Accordingly, pure tantalum (Ta) was deposited onto Ti6Al4V substrate surface as intermetallic layer then to form a TaO2 thin film, Ta was deposited onto the sample surface in the presence of oxygen by using physical vapor deposition magnetron sputtering (PVDMS). Corrosion testing was carried out in fetal bovine serum (FBS). The corrosion test in FBS medium confirmed that the corrosion resistance of the TaO2 - coated Ti6Al4V alloys was significantly higher than the uncoated Ti6Al4V substrate due to the decrease in corrosion current density (Icorr) for the coated substrate with high thin-film adhesion. Wear testing was carried out on uncoated and coated Ti6Al4V substrates in the presence of FBS medium under 15 N load (natural walking load) at 1.09 m/s (simulated medium walking speed). The tests revealed that the specific wear ratio of TaO2 coating was significantly lower than the uncoated substrate wear ratio. The average friction coefficients obtained were 0.183 and 0.152 for uncoated substrate and TaO2 thin film coating, respectively. So, due to the noticeable corrosion and wear resistance characteristics of the TaO2 coating, it is suggested for hip joint implant.