Synthesis of Ca,Y-zirconia/hydroxyapatite nanoparticles and composites

Zirconia/hydroxyapatite composites were prepared by mixing hydroxyapatite (HA) and ZrO2 nanoparticles were prepared by precipitation synthesis. Nanoparticle composites with microporous structure and with a grain size of up to 10 μm and a density of 94% were obtained. Due to the diffusion of Ca ions from HA to ZrO2, phase transformations took place in the composites during sintering. HA decomposed into a mixture of HA and calcium phosphates and simultaneously calcium zirconate was formed. Hardness and modulus of elasticity decreased with increasing porosity of the ZrO2/HA composites. The Ca-ZrO2/HA composites showed a higher bioactivity in simulated body fluid (SBF) testing than those of Y-ZrO2/HA. The osteoblast cells adhered more extensively to the Ca-ZrO2/HA composites than to the Y-ZrO2/HA ones. The effect of the microstructure and the chemical composition has the mechanical and biological properties could be used to optimize the mechanical and biological acceptability of the composites in bone repairs.