Preparation of amorphous calcium phosphate/triclcium silicate composite powders

The amorphous calcium phosphate (ACP)/tricalcium silicate (Ca ₃SiO₅, C₃S) composite powders were synthesized in this paper. The exothermal behavior of C₃S determined by isothermal conduction calorimetry indicated that the ACP could be synthesis by chemical precipitation method during the induction period (stage II) of C ₃S. The composite powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results indicated that nanosized ACP particles deposited on the surface of C₃S particles to form core-shell structure at pH=10.5, and the nca/np of ACP could be controlled between 1.0 and 1.5. The core-shell structure is stable after sintered at 500 0C for 3 h to remove the β-cyclodextrin (β-CD). As compared with the irregular C₃S particles (1∼5 μm), the composite powders particles are spherical with a diameter of 40∼150 μm. Therefore, to obtain the smaller size of composite powders, it is expected to avoid the aggregate of C₃S particles in the aqueous solution by addition of dispersant. As compared with C₃S, the composite powders may contribute better injectability, strength and biocompatibility.