Effect of ZrO_2 additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO_2-P_2O_5-CaF_2 bioactive glass-ceramics

摘要

A series of ZrO_2 doped MgO-CaO-SiO_2-P_2O_5-CaF_2 bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sed-imentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca_5(PO4)_3F (fluorapatite) and β-CaSiO_3 (β-wollastonite). m-ZrO_2 (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO_2 (tetragonal zirconia) increased the crystallization temperature of Ca_5(PO_4)_3F and declined the crystallization temperature of β-CaSiO_3. t-ZrO_2 greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell.