Potential Tribological and Antibacterial Benefits of Pulsed Laser Deposited Zirconia Thin Film on Ti6Al4V Bio-alloy

Demand for artificial body implants has been on the rise over the years. However, wear and bacterial infection are identified as two major reasons that can lead to inflammation and implant failure. In this communication, the advantages of pulsed laser deposited zirconia thin film on Ti6Al4V bio-alloy at room temperature and at an elevated substrate temperature are discussed wherein a comparison of the change in surface roughness, wettability, surface free energy, tribological and antibacterial properties of uncoated and zirconia coated Ti6Al4V samples is presented. The results of tribological analysis carried out using a standard ball-on-disc tribometer at different loads (2N, 5N and 7N) exhibited advantageous effects of zirconia coating on Ti6Al4V. Prominently, the sample coated at 200 C substrate temperature maintained very low coefficient of friction up to hundreds of sliding cycles and showed a notable reduction in the wear rate by 49% at 5N load. The in vitro bacterial retention test showed a clear inhibition in growth of Staphylococcus aureus and Klebsiella pneumonia bacteria on the surface of the coated samples indicating the possibility of prevention of biofilm formation. More than 50% reduction in density of Staphylococcus aureus was observed on coated sample in comparison to pristine Ti6Al4V and this can be attributed to reduction in surface energy of the sample after coating. Additionally, the observation of a larger number of decimated bacteria on coated samples by fluorescence microscopy revealed superior antibacterial properties of zirconia coating. The novelty of this work is the use of pulsed laser deposition technique for zirconia coating which dearly improves tribological and antibacterial properties of Ti6Al4V simultaneously; this shows prospects of increasing durability of artificial implant in the human body.