Preparation Of β-TCP/HAP Composite Bioceramics

Calcium hydroxyapatite (HAP, Ca10(PO4)6(OH)2) is a major inorganic constituent of bone. It has osteoconductive property. However, HAP has a problem of poor biodegradation.β-tricalcium phosphate (β-TCP,β-Ca3(PO4)2) is a bioactive and biodegradable material.β-TCP/HAP biphasic ceramics have been tried to improve the poor biodegradation characteristics of HAP ceramics.β-TCP/HAP ceramics is expected to induce bone growth without changing the osteoconductive properties of HAP. However, it is difficult to sinter denseβ-TCP/HA ceramics, for the phase transition temperature fromβ- toα-TCP is lower than a normal sintering temperature.Theβ-TCP granules with the range of diameter from 314μm to 800μm were prepared by dispersing the blend ofβ-TCP and aqueous solution of gelatin. After moulded, sintered and compounded by dipping in the HAP sol, the composite ceramics was prepared. It has a new structure: the body is made up ofβ-TCP granules and the interspace among granules is filled by HAP. Mg2+ and Na+ were used to improve the sintering property of the ceramics.In this paper, by analyzing the thermogravimetric curve ofβ-TCP/gelatin granules and the influence of oil temperature, stir rate, additive content and cooling temperature on the diameters of granules, the optimum technique was established; the influence of Mg2+ and Na+ on sintering and mechanical properties was analyzed and the mechanism was studied; the biodegradation experiment of the composite ceramics was made in solution of TRIS/HCl, and the data of degradation was analyzed. Theβ-TCP granules with the range of diameter from 314μm to 800μm were prepared by controlling the oil temperature at 30°C, stirring at 300rpm and cooling at 0°C. The mechanical property of the bioceramics reached 17.29MPa when theβ-TCP was doped by 1wt% MgO and sintered at 1150°C; Due to the addition of Na introduced the liquid phase at high temperature, the sintering property of bioceramic improved and Ca10Na(PO4)7 appeared in bioceramics. The mechanical property of bioceramics with 2wt% Na2O reached 8.1 MPa.The results of degradation showed thatβ-TCP granules were degraded and the HAP filled the interspace among granules was hold.