鋰鋁矽酸鹽玻璃陶瓷性質與結晶過程之研究

Abstract

本研究以溶膠-凝膠法製備出成分為 Li2O-Al2O3-7SiO2的鋰鋁矽酸鹽凝膠 粉末，經玻化處理使其結構緻密，並嘗試控制結晶熱處理使其結晶化而獲 得透明且極低熱膨脹係數的鋰鋁矽酸鹽係玻璃陶瓷材料使其結構緻密，並 嘗試控制結晶熱處理使其結晶化而獲得透明且極低熱膨脹係數的鋰鋁矽酸 鹽系玻璃陶瓷材料，並探討氧化物成核際TiO2與ZrO2的添加對其性質與結 晶過程的影響。實驗過程中，以示差熱分析儀找出適當的成核與結晶溫度 ，並求出與晶體成長相關的動力參數。然後將試片進行不同時間與溫度的 熱處理， X-射線繞射儀被用來鑑別在不同熱處理條件下，析出的結晶相 ，並以掃描式電子顯微鏡觀察試片的微觀結構，最後再利用熱機械性質分 析儀測量試片的熱膨脹係數。在1000 ℃以下Virgilite為主要結晶相，其 玻璃陶瓷可呈現透光性1200℃時beta-spodumen為主要結晶相，此時玻璃 陶瓷呈現白色，Virgilite具負的熱膨脹性，少量的Virgilite結晶相析出 可大幅地降低熱膨脹係數。TiO2較ZrO2的添加更能有效的促進成核，其結 晶活化能約較ZrO2減少一半，然而TiO2的添加有不利透明的傾向，其玻璃 呈現淡褐色透明。 The LAS powders were produced by sol-gel process in this study .The powder were denser through vitrification treatment.We tried to control crystallization heat-treatment in order to get moretransparent and low thermo-expansion of LAS glass ceramic, then study the relation of nucleus addition to crystallization. The temperature of nucleation and crystallization were determined byDTA in this experiment and the kinectic parameters of crystallization were also.The phase of crystallization were identified by XRD and the microstructureanalysis were by SEM. The coefficient of thermo-pansion were measure by TMA.Below 1000℃,the glass ceramics are transparent and it's primary phase is Virgilite.The glass ceramic appears white color and it's primary phase change to beta-spodumene around 1200℃.Virgilite with negative thermo-expansion ,it's formation can dramatic reduced the coefficient of thermo-expansion.The nucleus addition of TiO2 is more effectivethan ZrO2.Then the activation energy of crystallization is more below.