Influence of processing parameters and heat treatment on phase composition and microstructure of plasma sprayed hydroxyapatite coatings

Air plasma spraying process was employed to fabricate various hydroxyapatite(HA) coatings on titanium substrates. The influence of processing parameters on the phase composition and the microstructure of the obtained coatings was investigated. The effect of heat treatment on as-sprayed coating in terms of the crystallinity and microstructure was also studied. The phase composition of coatings was analyzed by X-ray diffraction(XRD) and FTIR. The surface and cross-section morphologies and microstructure of coatings as well as the morphology of feedstock were evaluated using scanning electron microscope(SEM). The crystallization temperature of amorphous HA phase in as-sprayed coating was examined by using differential thermal analysis(DTA). The results suggest that phase composition and microstructure of as-sprayed HA coatings strongly depend on the spraying parameters, and heat treatment at 760 °C for 2 h is one of effective means for increasing the crystallinity and improvement in microstructure of as-sprayed HA coatings.