玻璃冷却速率对锂铝硅微晶玻璃晶化行为和结构的影响

玻璃成型过程中冷却速率对Li₂O-Al₂O₃-SiO₂(LAS)微晶玻璃的晶化行为及其结构均匀性具有重要影响. 有限元分析表明, 10 mm厚玻璃冷却速率显著低于2 mm厚玻璃, 冷却15 s以上玻璃的中心温度仍高于700℃, 对应的基础玻璃极易出现“析晶结石”. 利用DTA、IR、SEM等技术分析不同厚度LAS玻璃及其微晶玻璃的显微结构, 8 mm厚的玻璃冷却速率低, 样品心部析出初始晶核, 并在热处理阶段形成β-锂辉石固溶体相, 而样品表面层却为β-石英固溶体相; 与此相反, 3 mm厚的玻璃冷却速率高, 没有初始晶核生成, 热处理后得到单一均匀的β-石英固溶体相. 因此, 提高玻璃冷却速率、控制玻璃温度均匀性是制备结构均匀LAS微晶玻璃的关键.

Effect of Glass Cooling Rate on the Crystallization Behavior and Structure of Lithium Aluminosilicate Glass-ceramics

The glass cooling rate during forming process has significant effect on the crystallization behavior and structural uniformity of Li2O-Al2O3-SiO2(LAS) glass-ceramics.Finite element analysis indicated that the cooling rate of 10 mm thick glass was notably lower than that of 2 mm thick glass.The central temperature of LAS glass was still above 700℃ even after the sample was cooled for 15 s,which led to the formation of crystal stones in the parent glass.The microstructure of LAS glass and glass-ceramics with different thickness were analyzed using DTA,IR and SEM.Since the 8 mm thick glass cooled slowly,primary crystal nuclei were generated in the glass interior.After heat treat-ment,a β-spodumene phase was formed in the interior,while a β-quartz solid solution phase formed on the surface.On the contrary,primary crystal nuclei were not generated in the 3 mm thick glass due to its high cooling rate.A single and uniform β-quartz solid solution phase was found after heat treatment.Therefore,the high glass cooling rate and the temperature uniformity of glass are very important for the preparation of structurally uniform LAS glass-ceramics.