【摘要】 本文采用DTA、XRD,SEM等测试手段详细地研究了MgO-Al₂O₃-SiO₂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·Al₂O₃·SiO₂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-2O₃·SiO₂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。更多还原

【Abstract】 The surface crystallization process in MgO-Al₂O₃-SiO₂ 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·Al₂O₃·SiO₂ 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·Al₂O₃-SiO₂ 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·Al₂O₃·SiO₂.更多还原