Sintering Behavior and Kinetic Evaluation of Hydroxyapatite Bio-ceramics from Bovine Bone

The Sintering behavior and kinetic evaluation of the bio-ceramics from bovine bone are investigated by stepwise isothermal dilatometry (SID), X-ray diffraction (XRD) and scanning electron microscope (SEM). The isothermal shrinkage data obtained from SID could be well analyzed to get kinetic parameters according to the empirical rate equation developed by Makipirtti-Meng, dY/dt = nk(T)Y(1-Y)[Y/(1-Y)], where Y is the fractional volume shrinkage during sintering process and n a dimensionless exponent. The apparent activation energy ∆E values obtained for 1000-1100°C and 1100-1250°C are 84.1 and 52.8 kJ/mol, respectively. Correspondingly, the exponent n that can be served to reveal the morphology changing during the sintering process are also much different in the two temperature ranges, which is well consistent with the SEM observation.