Hydrothermal Processing for Increasing the Hydroxyl Ion Concentration in Hydroxyl Depleted Hydroxyapatite
Thermal spraying is commercially used to produce hydroxyapatite coatings, but the high temperature depletes hydroxyl ions in the structure. To return hydroxyapatite to its original state, it is necessary to restore the hydroxyl ion content in the structure. In this work, the effect of hydrothermal treatment on the hydroxyl ions was investigated in hydroxyapatite powder and thermally sprayed hydroxyapatite coatings. Samples were hydrothermally treated at 200 °C for 24 h and 48 h. Chemical phases were determined by X-ray diffraction, functional groups and hydroxyl ion concentration was examined by Fourier transform infra-red spectroscopy. Results showed that hydrothermal processing of hydroxyapatite coatings at 200 °C for 48 hours produced the greatest increase in the hydroxyl ion concentration by 29%.
D. Ubele et al., "Hydrothermal Processing for Increasing the Hydroxyl Ion Concentration in Hydroxyl Depleted Hydroxyapatite", Key Engineering Materials, Vol. 762, pp. 42-47, 2018