The Study On The Magnetic Machinable Bioactive Glass-ceramics

The constant magnetic field and electric field can stimulate the formation of bones and quicken the healing of the wounded bones. According to the biological feature that magnetic field can stimulate the growing of bone cells, a kind of magnetic machinable bioactive glass-ceramic has been studied, which not only with biocompatibility and bioactivity but with relative high strength , toughness and machinability.Glass-ceramic in the K2O-MgO-CaO -SiO2-P2O5-Fe2O3-F system were studied in this thesis. Through changing the content of the additives the effect of additives on the microstructure and properties of magnetic machinable bioactive glass-ceramic and the effect of mechanism were probed. The nucleation and crystallization were determined by DTA curve. The crystalline phase , microstructure and physical properties have been investigated by XRD, SEM, EDS and ASTM Ceramic testing system et al. The results show that the relation between the content of ZnO, Fe2Os and ZrO2 and physical properties is non-linear. When the content of ZnO is 4wt% , that of Fe2O3 is 6wt% and that of ZrO2 is 4wt%, synthetic properties is the best in this system. Flexural strength is 190.26MPa, fracture toughness is 3.35 MPa m1/2, microhardness is 411HV, saturation magnetization is 3.818 Am2/Kg and curies temperature is 124 C. Both ZnO and Fe2O3 with proper content can improve the crystal growth, framework and a micro-morphology with a large aspect ratio and interlocking, which are beneficial to improving strength and toughness. ZrO2 can increase the toughness of material because of the phase transformation from t-ZrO2, and acclerate crystal growth of mica with claviform together with F. Three additives can offer nucleuses being nucleating agent. There are multi- effect with two or more additives, which is efficient in improving crystal with less radius and larger strength.The effect of temperature schedule on crystalline phase and microstructure and the effect of phase and microstructure on properties were analyzed in this this.To increase crystallization time and raise temperature have the same effect on crystallization. The large size of crystal, the higher strength and toughness. The more content of mica with sheet structure, the better machinability. In some extent, there are several toughening mechanism: the phase transformation from t-ZrOi, the crack defection and the dispersion.MMBGC immersion in simulated body fluid (SBF) and MMBGC and BG implanted in rabbits were examined by SEM, EDS, EPMA and Raman spectrum et al. The results reveal that MMBGC has good biocompatibility and bioactivity. So for the study on magnetic machinable bioactive glass-ceramic still has not reported. The author hold that it is a new type of artificial bone material which has great potentialities.