Morphology and composition of hydroxyapatite coatings prepared by hydrothermal treatment on electrodeposited brushite coatings

Highly pure brushite (CaHPO4. 2H(2)O) coatings on porous Ti6Al4V substrates were prepared by electrodeposition from aqueous electrolytes. The influence of hydrothermal treatment parameters on brushite-to-hydroxyapatite conversion and the morphology and phase composition of hydroxyapatite (HAP) coatings was studied. It was found that the content, Ca/P atomic ratio, grain size and pore size of HAP in coatings increase with increasing hydrothermal treatment temperature, and that increasing the pH value can promote brushite-to-HAP conversion and reduce the grain size of HAP. Under optimal conditions, highly pure HAP coatings with needle-like crystals and non-stoichiometric form, which are similar to those of calcium phosphate in human bone, can be obtained. (C) 1999 Kluwer Academic Publishers.