Physico-chemical properties and ultrasonic characterization of calcium phosphate ceramics

Abstract

Calcium phosphate compounds have been studied for biomedical applications due to their chemical and structural similarity to the mineral phase of bone and tooth. The composition, physical and chemical properties, crystal size and morphology of synthetic apatite are extremely sensitive to preparation conditions and sometimes it resulted into non- stoichiometric calcium deficient hydroxyapathite (Hap) powders. The present paper refers to calcinations of calcium phosphate ceramics at 800 and 1000oC. The effect of heat treatment were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). FTIR spectra showed the presence of various PO43- and OH-groups present in the powders. Powders compacted and sintered at 800 and 1000oC showed an increase in density. The main objective of the paper is a comparison of the results obtained by the previous methods to those obtained using the ultrasonic air-coupling technique. Modulated ultrasonic signals of 500 kHz central frequency have been transmitted through the calcium phosphate ceramics specimens. Correlation between signals allowed some conclusions concerning density, porosity and preparation temperature influence on these specimens. These comparisons and correlation of methods, allow a better characterisation of such important materials