Studies On Preparation Of Ca-P Bioceramic By Using Hydrothermal Process

In the present master thesis, tetraethyl silicate (TEOS) is used as silicon resource, which is used to prepare silicon gel powder by the Sol-Gel method. The SiO2 amounts are 10wt%, 20wt% ,and 30wt% respectively. The Ca,P precipitant powder is prepared by reacting CaCOs with H3aPO4 then drying, and Ca/P is 1.6. The Si gel and Ca,P precipitant powder are mixed to obtain Ca,P,Si predecessor powders. The spherical fatty acid (as making pore agent) and 3% PVA solution (as sticking agent) are added into powders, then pressed, put into autoclave at 240℃ for 8h,and sintered at 1050℃: and 1200℃, CaO-P2O5-SiO2 bioceramics are obtained. For further studying effect of hydrothermal technique on composition and structure of CaO-P2O5-SiO2 bioceramics. The sample sintered at 1050℃ is carried out by secondary hydrothermal treatment.It has been shown from XRD analysis that there are HA and p-TCP in all samples. In the samples treated by hydrothermal technique there are main crystalline phase HA andp-TCP ,there are CaCO3 and CaHPO4 also, there is no CaSiO3. SiO2 may exist as amorphism. In the samples sintered at 1050℃ there are main crystalline phases HA andp-TCP, a small amount of CaSiOs. In the samples sintered at 1200℃ there is main crystalline phase β-TCP, and HA transfers to p-TCP. The amount of CaSiO3 increases. In the sample sintered at 1050℃ and treated by secondary hydrothermal technique there are maincrystalline HA and β-TCP, and β-TCP transfers partly to HA. It has been shown from SEM that the structure of porous Ca-P bioceramicprepered possesses macropores with size about 500μ and micropores with size 1 -5μm, and it forms net structure, there are passages pass through macropores and micropores. It has been shown that in the samples sintered at 1050℃ and 1200℃,the increase in SiO2 amount is useful to form β-TCP and CaSiO3 and is not useful to form HA. Sintering at 1200℃ makes the crystals melt, amounts of needle-like HA crystals decrease and amounts of grain-like β-TCP and CaSiO3 increase. In the samples at 1050℃ and treated by secondary hydrothermal technique for sample with SiO210wt%, the needle-like crystals grow into longer-needle crystals. For samples with SiO220wt% and 30wt%, the grain-like crystals grow into big-grain crystals.A series of tests on properties of the CaO-P2O5-SiO2 bioceramics have been carried out. Effects of making pore agent, SiO2 amounts ,sintering temperature, secondary hydrothermal treatment on density, sop-capability, porosity, and compressive strength have been studied. In vitro dissolution test of materials prepared in SBF and hemolytic, cruor tests have been carried out. It has been shown that the materials prepared possess a certain biodegradation ,and it possesses good blood capability.