THERMAL-EXPANSION APPLICATION TO ASSESS CALCINATION OF BOVINE HYDROXYAPATITE

The thermal behaviour of hydroxyapatite prepared from bovine tibia was followed. Combined differential thermal analysis and thermogravimetric analysis were carried out for this biological apatite. The stability range was followed through thermal expansion measurements of the calcines and supplemented by X-ray diffraction analysis and scanning electron microscopy. The existing structure of the hydroxyapatite persisted up to and above 1000-degrees-C with the development of high crystallinity as proved by their diffractograms and surface topography of the samples heated between 700 and 1000-degrees-C. The flattened turning points of dilatometric curves for samples calcined above 800-degrees-C along with reduced expansion values prove completed calcination. Detailed knowledge of the thermal behaviour is helpful for well balanced calcination process involving, therefore, minimal fuel consumption. The importance of hydroxyapatites of various origins lie on their compatibility as bone substitute. Complete structural characterization of such potential graft material needs to be carried out to assess its biocompatibility.