Preparation and property characterizations of HAp-5.0wt%SiO_2 bioceramic composites

HAp-5wt%SiO2 bioceramic composites were prepared successfully by sintering the powders of hydroxyapatite(HAp) mixed directly with additive of 5.0wt%SiO2 at 1200℃.XRD and FT-IR analyses of the sintered samples demonstrate that the SiO2 additive promotes the thermal decomposition of HAp.The major phase compositions of the HAp/SiO2 composite consist of α-TCP,HAp,Ca2P2O7,bioglass(BG),and etc.The in vitro bioactivity assessments show that the petal-like apatite sediments appear on the surface of the sample after soaking for 24h in stimulated body fluid(SBF),and the plate sediments form as the soaking time is increased to 72h.After further immersing up to 120h,the sample surface is fully covered by a thicker bone-like apatite layer.XRD analyses indicate that the apatite layer is mainly composed of hydroxycarbonate apatite(HCA),which is the major inorganic component of the human bone.As compared with pure HAp,the synthesized HAp-5wt%SiO2 bioceramic composite has a superior in vitro bioactivity,and it can be expected to act as a potential material for bone repair.