摘要
本文采用DTA、XRD,SEM等测试手段详细地研究了MgO-Al_2O_3-SiO_2系统玻璃的表面晶化过程。发现在玻璃的自由表面层中析出了密集的β石英固溶体结晶粒子,靠近该结晶粒子群的玻璃相中有大小为500—1000(?)的球形分相粒子群出现,其数量随表面深度的增加逐渐由密集、连续的分布过渡为呈指数规律减小的分布状态,而且分相粒子的大小与深度无关。而研磨表面的结晶层则由α堇青石、β石英固溶体、透锂长石型MgO·Al_2O_3·SiO_2晶体三种晶相组成,并呈树枝状向玻璃内部长大,靠近结晶层的玻璃相中也没有球形分相粒子群出现。在950℃下热处理的玻璃中,β石英固溶体和MgO·Al-2O_3·SiO_2晶体的析出量均随热处理时间的延长有极大值出现,而α堇青石的析出量则一直随时间的延长而增大。
The surface crystallization process in MgO-Al_2O_3-SiO_2 glass was investigated by several methods including DTA, XRD and SEM.Aggregated particles of β-quartz preci-pitated from natural surface of the glass.The aggregation of non-crystalline spherical particles of about 500—1000?. was observed in the region contiguous to the surface layer containing β-quartz.However, the number of spherical particles decreases with depth below the crystallized surface according to the logarithmic law, with the same particle-size substantially regardless of the depth. The precipitation of β-quartz,MgO·Al_2O_3·SiO_2 and α-cordierite was observed for the sample with polished surface. The surface crystal-lization in this case developed into the glass with the dendrite structure. In the glass, the amounts of β-quartz and MgO·Al_2O_3-SiO_2 reached the maximum value during iso-thermal treatment at 950℃, whereas the amount of α-cordierite increased monotonously with time.This suggests that α-cordierite is formed not only by the direct precipitation, but also by the transformation of β-quartz and MgO·Al_2O_3·SiO_2.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1991年第3期202-209,共8页
Journal of The Chinese Ceramic Society
关键词
氧化镁
氧化铝
二氧化硅
玻璃
晶化
surface crystallization
glass
natural surface
polished surface
α-cordierite
