LAUSR

Abstract The present study concerns a detailed microstructural characterization and evaluation of surface mechanical properties of the plasma spray deposited hydroxyapatite (HA) based (HA + 50 wt% TiO 2 and HA + 10 wt% ZrO 2 ) composite coatings on Ti-6Al-4V substrate and studying the effect of heat treatment on it. Heat treatment of plasma spray deposited sample has been carried out at 650 °C for 2 h (for HA + 50 wt% TiO 2 coating) and at 750 °C for 2 h (for HA + 10 wt% ZrO 2 coating). The microstructure of the as-sprayed coating shows the presence of porosities and un-melted particles on the surface, the area fraction of which is reduced after heat treatment. There is an improvement in hardness after heat treatment from 2.15 GPa to 2.2 GPa in HA + 50 wt% TiO 2 coating and from 1.1 GPa to 2.3 GPa in HA + 10 wt% ZrO 2 coating. There is a marginal enhancement in the Young's modulus from 78 GPa (in as-sprayed coating) to 80 GPa (due to post heat treatment) in HA + 50 wt% TiO 2 coating and from 55 GPa (in as-sprayed coating) to 70 GPa (due to post heat treatment) in HA + 10 wt% ZrO 2 coating.