The influence of current plasma spraying on the characteristics of titanium/hydroxyapatite composite coatings

Plasma sprayed hydroxyapatite (HA) coating on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implants. In this study HA-Ti composite powder with 50 wt% Ti prepared by mechanical alloying and it was deposited on to Ti alloy by means of atmospheric plasma spraying. Also the influence of spraying current on the characteristics of the composite coatings was investigated. Structural characterization techniques including XRD and SEM were utilized to investigate the microstructure, morphology and phase composition of the coatings. Also microhardness of the composite coatings was studied. The investigation showed that the composite coating sprayed at a current of 600 A and a stand-off distance of 10 cm possessed the most value of microhardness and bond strength. Also it possessed the highest quality in terms of amount of porosity and the surface morphology.