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采用热分析和红外光谱分析法研究了 Si O2 凝胶薄膜热处理过程中的热失重和结构变化 ,确定了薄膜在室温～ 673 K温度区间的分级热处理工艺和玻璃化温度。在熔模铸造壳型内表面基体玻璃涂层上制备了两类无裂纹 Si O2 薄膜涂层。析晶实验结果表明 ,第一类薄膜涂层在高温下为方石英 ,第二类薄膜涂层经 1 773 K保温 1 5min处理后为稳定玻璃态。将深过冷 Cu70 Ni30 合金熔体浇入两种涂层壳型中分别获得了 90 K和 1 98K的过冷度 ,表明涂层结构对合金熔体过冷遗传性有影响
The thermal weight loss and the structure change of Si O2 gel film during heat treatment were studied by means of thermal analysis and infrared spectrum analysis. The heat treatment and glass transition temperature of the film were determined at room temperature to 673 K. Two types of crack-free Si O2 thin film coatings were prepared on the glass substrate of the investment casting shell inner surface. Crystallization experimental results show that the first type of thin film coating is cristobalite at high temperature and the second type of thin film coating is stable glass state after being treated at 1 773K for 15min. The undercooling of Cu70Ni30 alloy into two coating shell forms respectively obtained undercooling of 90 K and 1 98K, indicating that the coating structure has an influence on the inheritance of alloy undercooling