高热膨胀Na_2O-MgO-Al_2O_3-SiO_2微晶玻璃的制备及性能研究

Preparation and Properties of High Thermal Expansion Na_2O-MgO-Al_2O_3-SiO_2 Glass-ceramics

采用传统熔体冷却法制备了Na_2O-MgO-Al_2O_3-SiO_2玻璃并采用整体析晶工艺制备了微晶玻璃。利用DSC、XRD、SEM等测试手段研究了微晶玻璃的析晶行为和显微结构,探讨了热处理制度对该体系微晶玻璃热膨胀系数、密度、抗弯强度、显微硬度等性能的影响。研究结果表明,当晶化温度为800℃时该体系微晶玻璃主晶相为颗粒状霞石晶体(NaAlSiO_4);当晶化温度达到900℃时玻璃中开始析出镁橄榄石(Mg_2SiO_4)晶体;延长保温时间可显著促进析晶但对晶体种类没有影响。析晶后微晶玻璃的密度、热膨胀系数、抗弯强度和显微硬度值显著增加,其最高热膨胀系数可达14.1×10-6℃-1。所制备的微晶玻璃具有很好的机械性能,当热处理温度为1000℃时,其抗弯强度和显微硬度分别达160 MPa和7.8 GPa。

Na_2O-MgO-Al_2O_3-SiO_2 glass-ceramics were prepared by conventional melt quenching technique and body crystallization process. The crystallization behavior and microstructure of glass-ceramics were investigated by DSC,XRD and SEM. The influences of the heat treatment conditions on CTE,density,bend strength and hardness were discussed. The results show that the main phase in glass-ceramic is Na AlSiO_4 when the crystallization temperature is 800 ℃,and Mg_2SiO_4 crystal forms when treating temperature increases to 900℃. Increasing crystallization time can significantly promote crystallization but had no effect on the crystal species. The density, CTE, bend strength and micro-hardness of prepared glass-ceramics increased significantly by heat treating. When crystallization temperature increase to 1000 ℃,a glass-ceramic with high thermal expansion and good mechanical properties can be obtained in low cost,and the CTE,bend strength and micro-hardness of prepared glass-ceramic is 14. 1 × 10-6℃-1,160 MPa and 7.8 GPa,respectively.