高熱膨脹氧化物玻璃用於熱熔擠出及電絕緣特性之應用研究

Abstract

本研究選用TiO2-Na2O-SiO2-B2O3 (TN-SB)氧化物玻璃,進行熔融擠出與熱電偶鍍膜兩種應用測試。經由調整TN-SB玻璃配方之B2O3/SiO2比例，以固相粉體混合，再以高溫1250 ˚C, 0.5 h熔融製備氧化物玻璃。透過數種熱分析量測不同配比的氧化物玻璃之玻璃轉換溫度、軟化點、熱膨脹係數及黏度。另外，利用碳化矽加熱棒與鐵鉻鋁加熱絲組合一加熱體，並以薄層陶瓷耐火綿、高氧化鋁澆注材製成之袖套，及高氧化鋁熱絕緣層形成之三層斷熱結構，組合為一可用於高溫熔融擠出之組件。在提供最高187 W輸出之電源供應下，此組件可於10分鐘內達1300 ˚C。另外，設計合適之加熱基板及送料裝置，利用此高溫噴頭，示範氧化物玻璃進行高溫熔融擠出之可行性，達到持續200 s之擠出時間與平均25 mm.s-1之擠出速度。研究工作並完成三種銅基熱電偶之玻璃鍍膜製備工作，並校正熱電偶之短時間與長時間(≤30 hr)之熱電位輸出，文中並討論高溫持溫產生之電位誤差之可能原因。

This study selected TiO2-Na2O-SiO2-B2O3 (TN-SB) glasses for the applications of melt extrusion and electrical insulation layer on Cu-based alloy thermocouple. First, the oxide glasses adjusting SiO2/B2O3 ratio were prepared by melt-quenched at 1250 ˚C for 30 min. Thermal properties of the glasses were investigated, including glass transition temperature (Tg), softening temperature (Ts), thermal expansion coefficient (CTE) and viscosity. Moreover, a melt extrusion module with an electromagnetic heating plate and a feeding system were assembled with a heating module, which combined a SiC heating element and Fe-Cr-Al heating wire for heating, and covering with thin ceramic fiber, castable outer sleeve, and a refractory support made by high Al2O3 ceramic board as thermal insulation layers. After providing 187 W power at most, the nozzle could reach 1300 ˚C in 10 min. Also, the formability of the oxide glass by extrusion was tried and capable of continuous extrusion over 200 s at an average speed of 25 mm.s-1. This work also completed a glass coating on various Cu-based thermocouples, calibrated the potential output in short and long ( 30 hr) terms. The possible causes of the deviation of the potential of the thermocouples were discussed.