Insights into the microstructure and coating integrity of TiO2 coatings on conventional and laser shock peened Ti–6Al–4V alloy

Widely explored for its ability to improve surface and mechanical characteristics, Laser Shock Peening was evaluated in this study by comparing microstructural features, mechanical behavior, and coating robustness of Ti-6Al-4V substrates with and without peening. To improve substrate protection, TiO 2 was deposited by Electrophoretic Deposition, with voltage and time optimized as process parameters. Rutile TiO 2 was synthesized through the sol-gel method and confirmed by physico-chemical characterizations. An optimized deposition voltage of 70 V and 4-minutes process time were employed for LSP-ed substrates to evaluate their comparative effects against conventional Ti-6Al-4V. The microstructural studies revealed uniform, crack-free coatings at optimized parameters, with enhanced surface roughness. An increase in hardness from 659.5±15.1 HV to 952.1±34.7 HV was achieved through Laser Shock Peening. Similarly, the contact angle for LSP-ed coating was 19.45±0.86 °, in contrast to 30.81±0.79 ° for the unpeened, owing to the micro-surface roughness enhancement. Peened substrates demonstrated delayed crack initiation and propagation, as revealed by qualitative adhesion and scratch tests, attributed to dense dislocation networks induced by plastic deformation. Our findings establish the superiority of peened substrates over the conventional counterparts, as reflected in superior microstructural integrity and mechanical properties, positioning it as a promising surface modification approach for orthopedic bioimplants. • Rutile TiO 2 deposited over Laser shock peened and unpeened Ti-6Al-4V Alloy. • Optimized voltage of 70V and process time of 4 minutes gave dense, crack free coatings. • LSP-ed coating enhanced micro-surface roughness and hence improved mechanical behaviour. • LSP-ed substrates show superiority over unpeened substrate, positioning them as promising bioimplants.