SiO_2涂层结构对Cu_(70)Ni_(30)熔体过冷遗传性的影响

The Effect of SiO_2 Coating Structure on Undercooling Heredity of Cu_(70)Ni_(30) Melts

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 。

Thermal analysis and infrared spectrum are used to analyse the heat weightless and structural changes in SiO 2 sol gel thin film in the process of heat treatment. Grading heat treatment technology and glassy temperature in the temperature sections of thin film room temperature～673K are also determined. Two groups of SiO 2 thin film coatings without cracks are prepared on the glassy coating of inner surface basic body in the investment casting mold. The results from crystal analysis experiments indicate that the first group of thin films can be cristobalite under high temperature while the second group of thin films treated at 1773K for 15 min. can remain the stable vitreous state. Two kinds of 90K and 198K undercoolings can be obtained after the undercooled Cu 70 Ni 30 melts are poured into the coated molds with cristobalite and vitreous quarts, thus showing that the coating structure will have an important effect upon undercooling heredity of the melts.