Interaction of hydroxyapatite–titanium at elevated temperature in vacuum environment

In this study, the interaction between hydroxyapatite (HA) and titanium (Ti) at elevated temperature in vacuum environment was investigated. The 80 wt% HA–20 wt% Ti powder mixtures and 90 wt% HA–10 wt% Ti powder mixtures were dry pressed and heat-treated at 1100°C in vacuum environment. HA powders and the commercially pure Ti powders were used as controls. The heat-treated samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscope (SEM) and energy disperse spectra. XRD and SEM indicated densification of metallic Ti specimens during the in-vacuum heat treatment. Heat treatment of HA specimens in vacuum resulted in the loss of hydroxyl groups as well the formation of a secondary β-tricalcium phosphate phase. Metallic Ti was not observed in the in-vacuum heat-treated HA–Ti specimens. However, α-tricalcium phosphate, tetracalcium phosphate and calcium titanium oxide were observed for the in-vacuum heat-treated HA–Ti specimens. It was concluded that the in-vacuum heat-treatment process completely converted the metal–ceramics composites to ceramic composites.