Abstract
Calcium deficient hydroxyapatite with Ca/P atomic ratio comprised between 1.5 and 1.667 were densified by hot pressing. Hot pressed powders were transformed into hydroxyapatite-tricalcium phosphate biphasic ceramics. After hot pressing at 1200°C, fracture strength remained below 100MPa, this was explained by the allotropic transformation β→α of TCP above 1150°C. Ceramics hot pressed at 1100°C had a fracture strength of 150 MPa when the composition contained between 8 wt% and 12 wt% of β-TCP. For lower or higher β-TCP content the strength dropped. This proved the necessity of a precise determination of Ca/P ratio. Quantitative X-ray diffraction analysis allowed a better precision than wet chemical analysis with deviations below 0.005 on Ca/P values.
