CHEMISTRY AND SINTERING BEHAVIOR OF THIN HYDROXYAPATITE CERAMICS WITHCONTROLLED POROSITY

Hydroxyapatite ceramic tapes (several hundred micrometres thick) have been prepared at different porosity levels, using the tape casting tec hnique. The reactions, which occur during processing and sintering of the tapes, have been characterized by power X-ray diffraction analysis , differential thermal analysis (DTA), thermogravimetric analysis (TGA ), scanning electron microscopy (SEM) and Fourier transform infrared s pectroscopy (FTIR). Volume changes have been measured during different stages of heat treatment. These can be attributed to phase transforma tions of the starting materials, which determine the sintering behavio ur and final porosity of the samples. Measurements of the elastic modu lus were performed by the resonant frequency method. A cubic dependenc e on the relative density is found. Finally, some possible improvement s for the technique and selection of powders are suggested, based on t he reported results.