Synthesis and ultrasonic characterization of hydroxyapatite ceramic powders

Calcium phosphate compounds have been studied for biomedical applications due to chemical and structural similarity to the mineral phase of bone and tooth. The composition, physico-chemical properties, crystal size and morphology of synthetic apatite are extremely sensitive to preparative conditions and sometimes it resulted into non-stoichiometric calcium deficient hydroxyapatite (HAp) powders. The present paper refers to calcinations of hydroxyapatite ceramics at 600, 800 and 1000 degrees C. The effect of heat treatment was previously investigated by X-ray diffraction (XRD). The ultrasonic characterisation of hydroxyapatite powders were performed using the ultrasonic air-coupling technique. Modulated ultrasonic signals of 450 kHz central frequency have been transmitted through the hydroxyapatite ceramics specimens. Correlation between signals allowed some conclusions concerning density, attenuation and preparation temperature influence on these specimens. These comparisons and correlation of methods, allow a better characterization of such important materials.