Dependence of the mechanical properties of sintered hydroxyapatite on the sintering temperature

This paper discusses the dependence of microstructure and mechanical properties of sintered hydroxyapatite (HA) on the temperature of sintering. Hydroxyapatite powder was prepared by the precipitation method and its purity and crystallinity were evaluated via XRD. A set of specimens was produced from this powder and sintered in conventional furnace at temperatures ranging from 1140 to 1340 °C. Elastic moduli of the specimens have been measured ultrasonically; compression strengths—on the Instron testing machine. Information about the microstructure has been derived from the measured elastic moduli and then verified by analysis of photomicrographs of shatters. It is observed that the average shape of pores transforms from strongly oblate to round at higher sintering temperatures. This transformation leads, in particular, to increased strength of the material since the stress concentration near pores is reduced.