Sol–gel derived Al₂O₃/Gr/HAP nanocomposite coatings on Ti–6Al–4V alloy for enhancing tribo-mech properties and antibacterial activity for bone implants

Titanium and its alloys are substantially used as prosthetics, for internal screw fixation in the human body, due to their incredible chemical and mechanical properties. But, due to the low hardness and high coefficient of friction of titanium alloys, which led to poor wear properties. Hence, in the present work, nano-alumina/hydroxyapatite/graphene as the bioactive coating are deposited using the sol–gel method on the Ti–6Al–4V alloy to improve its biomechanical properties. After coating, the tribological behavior, antibacterial activity, and apatite nuclei in simulated body fluid were evaluated. The resultant coatings surface morphology and worn substrates were studied by scanning electron microscopy. The presence of alumina/hydroxyapatite/graphene was evidenced by energy dispersive X-ray peaks. The topography of the coated surface was inspected, using the atomic force microscope. The coatings on the Ti–6Al–4V alloy resulted in enhanced surface roughness for cell attachment and cell growth. The hardness of the coated and uncoated substrates was investigated by Vickers microhardness tester. The microhardness test reveals that coating substrates exhibits 72% hardness as compared to uncoated substrates. The tribological test was conducted by a pin-on-disc testing machine by varying the process parameters like load, velocity, and distance. The results show that the Ti–6Al–4V alloy with coating exhibited greater wear resistance as compared to the uncoated Ti–6Al–4V alloy. The biomimetic apatite was found on the coated surface after a period from 1 to 7 days when immersed in SBF at 37 °C, signifying an enhancement in apatite nucleation. Ti–6Al–4V alloy with nano-alumina/hydroxyapatite/graphene coating can be proved as a potential applicant for significant antibacterial activity in load-bearing performance in bio-implants.