Effect of Power and Stand-Off Distance on Plasma Sprayed Hydroxyapatite Coatings

Plasma sprayed hydroxyapatite coatings were deposited onto mild steel substrates under several power and stand-off distance conditions. The microstructure of the coatings was observed and imaged using scanning electron microscopy (SEM). The crystal structure and crystallinity of the coatings were analyzed using X-ray diffraction (XRD). The Ca/P ratio of the coating was measured using energy dispersive X-ray spectroscopy (EDX). The deposition efficiency of the coatings was measured by weighing the substrate before and after coating. The porosity, surface roughness, and microhardness of the deposited coatings were characterized by using ImageJ, surface profilometer, and Vickers microhardness tester, respectively. The results indicated that microhardness and deposition efficiency increased with increasing power and stand-off distance. Porosity, surface roughness, and crystallinity decreased as the Ca/P ratio steadily decreased.