Preparation And Properties Of CaSiO₃+B₂O₃+SrCO₃+CaF₂+ZnO/HA Biomedical Composite

Synthetic hydroxyapatite (HA) has good bio-compatibility, due to its composition closes to bones and teeth of vertebrate. When implanted into human body, synthetic HA can achieve tight bonding with bones, as a result of which, HA has been extensively studied as a bone substitute or coating for metallic implant. However, owing to the typical brittleness of hydroxyapatite ceramic, its application is greatly limited. Therefore, In order to enhance the comprehensive performance of the material, many researches have been dedicated to the synthesis of the composite bioceramic materials.In this thesis, based on wet synthesized hydroxyapatite powder ,the CaSiO₃, B₂O₃,SrCO₃,CaF₂,and ZnO were added into the powder in a certain proportion, The CaSiO₃+B₂O₃+SrCO₃+CaF₂+ZnO/HA biomedical composite was prepared by Non-pressure sintering. The phase constitution of the composite was studied by XRD and the microstructure was observed by SEM; In order to research into mechanics property, the bending strength was measured by the Universal testing machine controlled by computer; At last, preliminary experimental study on the biological characteristics of the composite was given.The results obtained in this thesis were as follows:1. In the composite, the hydroxyapatite crystal phase was predominant over the other crystal phases; the glass phase of wollastonite was filled into the gaps in the material, and the strength of the composite increased consequently, there were also lots of porous and cracks in the composite. The composite owned higher bending strength than the pure hydroxyapatite.2. The sintering temperature of the composite was lowered apparently with the addition of B₂O₃ and CaF₂; consequently, the decomposing of hydroxyapatite could be avoided at high temperature(>1300℃), the composite mechanics property could be enhanced.3. With the increase of the sintering temperature, the composite density increased, the porous rate of the composite decreased; consequently, the composite bending strength was enhanced.4. By comparison, with addition of 20% wollastonite, the composite bending strength got the best of the others.5. The reinforcing mechanism was the concerted actions of self-reinforcement, remnant stress, and whisker toughening.6. Preliminary experimental study on the biological characteristics of the composite showed that the composite rate of hemolysis was under the standard criteria (5%), no acute toxic reaction on the whole body.