THE INFLUENCE OF HIGH SINTERING TEMPERATURES ON THE MECHANICAL-PROPERTIES OF HYDROXYLAPATITE

The kinetics of the thermal decomposition of stoichiometric hydroxylap atite (HA) has been studied up to 1500 degrees C for the purpose of de termining the maximum admissible combinations of temperature and time for sintering HA. The influence of the sintering temperature on shrink age, density and grain growth is then investigated in the temperature range from 1000 to 1450 degrees C. Nearly theoretical density was achi eved above 1300 degrees C. A maximum fracture toughness is obtained fo r the samples sintered at 1300 degrees C whereas hardness increases up to a sintering temperature of 1400 degrees C. These results are discu ssed in terms of the roles of porosity and grain size.