Processing and properties of calcium phosphates bioceramics by hot isostatic pressing

Stoichiometric β-tricalcium phosphate (β-TCP), hydroxyapatite (HA) and biphasic calcium phosphate (TCP/HA 60/40 %wt, BCP40) powders were synthesized by chemical precipitation of aqueous solutions of diammonium phosphate and calcium nitrate. After a calcination treatment and a milling step, powders were shaped by slip-casting. The sintering temperature effect on the density and the average grain size was investigated. By natural sintering, densities between 98 and 99.8% were obtained. Hot Isostatic Pressing (HIP) treatment was carried out after a pre-sintering of these materials. Transparent or translucent samples were obtained, indicating a relative density very close to the theoretical value (>99.9%). Mechanical properties (three- point bending strength, fracture toughness, Young's modulus and Vickers hardness) were measured on hipped materials with similar grain size (∼0.7µm).