SiO_2—Al_2O_3—MgO—K_2O—MgF_2系玻璃陶瓷析晶机理及断裂机制

Crystallization and Fracture Mechanism of SiO_2—Al_2O_3—MgO—K_2O—MgF_2 Glass-ceramics

以SiO2—Al2O3—MgO—K2O—MgF2体系玻璃为基础,采用整体析晶法,在高温条件下制备出堇青石/氟金云母玻璃陶瓷。借助于综合热分析仪、X射线衍射仪和扫描电子显微镜等分析手段,研究了玻璃陶瓷的析晶机制、显微形貌和断裂机制。结果表明:所制备的玻璃陶瓷主晶相为板条状氟金云母和β-堇青石,经1 000℃保温3h热处理后,主晶相转变为镁橄榄石;以堇青石和氟金云母为主晶相的玻璃陶瓷断裂机理为穿晶断裂,以镁橄榄石为主晶相的玻璃陶瓷为沿晶断裂。在基础玻璃中添加5%B2O3,可抑制氟金云母相的析出,并提高玻璃陶瓷的致密度。

Cordierite/fluorphlogopite glass ceramics were fabricated with SiO2-Al2O3-MgO-K2O-MgF2 composition system via volume crystallization during heat treatment at high temperature.The crystallization,microstructure and fracture mechanism were investigated by differential thermal analysis,X-ray diffraction and scanning electron microscopy,respectively.The results show that the main phases of the glass ceramics are plate-like fluorphlogopite and β cordierite,and the main phase transforms into forsterite after heat-treated at 1 000 ℃ for 3 h.The fracture mechanism of cordierite/fluorphlogopite glass ceramics is a trans granular fracture,and that of forsterite containing glass ceramics appears an inter-granular fracture.The addition of 5％B2 O3 in the material system can suppress the crystallization of fluorphlogopite and improve the density of the glass ceramics.