Densification and Hardness Behaviour of Nanocrystalline Hydroxyapatite/β-Tricalcium Phosphate Composite Powders

In this study, dense, fine-grained biphasic calcium phosphate bioceramics were designed via sintering method. nanosize hydroxyapatite / β-tricalcium (HA/β-TCP) phosphate powders with average grain size of 80 nm were prepared by the wet chemical precipitation method with calcium nitrate and di-ammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The precipitation process employed was also found to be suitable for the production of sub-micrometre HA/β-TCP powder in situ. The sinterability of the nanosize powders, and the microstructure, mechanical strength of the prepared HA/β-TCP bioceramics were investigated. Bioceramic sample characterization was achieved by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and density measurements. Powders compacted and sintered at 800, 900, 1000 and 1100°C showed an increase in relative density from 57% to 93%. The results revealed that the maximum hardness of 229 HV was obtained for HA/β-TCP sintered at 1100°C.