The effect of powder processing on densification, microstructure and mechanical properties of hydroxyapatite

The influence of powder processing and sintering temperature on densification, microstructure and mechanical properties of hydroxyapatite (HAp) ceramics was studied. The as-dried, calcined and processed HAp powders were uniaxially compacted and sintered at various temperatures (1000–1400 °C) for 3 h. The as-dried and processed powders, attained 97% of theoretical density (TD) at 1100 °C; at higher sintering temperatures, the density of the as-dried powder compact was found to decrease. A uniform microstructure with fine grain size (2.3 μm) was observed for material obtained from processed powder, whereas exaggerated grain growth with closed pores were observed in as-dried and unprocessed powder compacts. The Vickersʹ hardness, fracture toughness and flexural strength of HAp were determined and a maximum value of 6.3 GPa and 0.88 MPam12 and 60.3 MPa, respectively were obtained for processed compact. The processing of HAp has improved its densification, microstructure homogeneity and mechanical properties.