Investigation on plasma electrolytic oxidation duty cycle on Ti6Al7Nb titanium alloy performance for biomedical application

In the current investigation, surface modification of Ti6Al7Nb is done with the help of the plasma electrolytic oxidation process to understand the effect of duty cycle on its performance. Ti6Al7Nb is a better alternative as compared to Ti6Al4V and Ti6Al4V ELI titanium alloys for biomedical applications because vanadium is replaced with niobium, which does not have adverse effects on cells like vanadium does. This study investigates the influence of plasma electrolytic oxidation (PEO) duty cycle on the coating properties of Ti6Al7Nb titanium alloy, focusing on thickness, hardness, surface roughness, pore size, and corrosion resistance. Na₂SiO₃, Na₃PO₄·12H₂O, and KOH was used as electrolyte for coating Ti-6Al-7Nb titanium alloy, PEO coating is done at constant voltage of 500 V. Five different duty cycle 20%, 30%, 40%, 50% and 60% are used to understand the effect of it on the performance of Ti-6Al-7Nb titanium alloy. For characterisation of coating SEM, EDS, XRD techniques are used. From current study it was noticed that coating thickness increases from 10.19 mm to 18.73mm as duty cycle increases from 20% to 60%, however hardness increases from 718.80 HV to 883.35 HV as duty cycle increases from 20% to 60%. It was observed that high duty cycle increases coating hardness and thickness due to intense discharge events. From EIS testing it was notice that coating is made-up of two-layer structure. Uniform distribution of electrolyte compositions was observed in PEO coated Ti-6Al-7Nb titanium alloy.