本研究目的在探討於固態氧化物燃料電池(SOFC)使用環境下，玻璃陶瓷接合劑和金屬連接板接合件的熱機疲勞性質與破裂模式，所使用的玻璃陶瓷為核能研究所開發代號為GC-9的材質，金屬連接板則是使用代號為Crofer 22 H 的商用肥粒鐵系不鏽鋼。分別在氧化及還原環境下，對接合件同時施予週期性的溫度以及剪力、張力的變動負載，以進行熱機疲勞實驗。 實驗結果顯示，剪力試片無論在空氣中的氧化環境或是濕氫氣體中的還原環境測試，其熱機疲勞壽命主要都是受到高溫區所受應力負載主導，壽命會隨著高溫(800 °C)施加負載的增加而減少。當在溫度達到高峰且施加應力負載為0.2倍的高溫剪力強度時，試片在兩種環境皆可以承受50個以上的熱機疲勞負載週期。而在熱機疲勞壽命中，試片在經歷795-800 °C頂溫區段的累積時間，與先前研究接合件在800 °C下的潛變壽命相當接近。從破斷面觀察，氧化環境實驗之試片多破裂於鉻酸鋇與玻璃膠的介面，而在還原環境多破裂於氧化鉻與玻璃膠的介面層。 張力試片在氧化與還原環境的測試結果，熱機疲勞壽命會隨著高溫(800 °C)施加的負載增加而減少。然而，張力的熱機疲勞壽命不只受到高溫區施加應力負載主導，也受到低溫區施加應力負載的影響，可能是因為玻璃膠在低溫時為脆性，對於張應力較為敏感所致。在氧化環境中，短壽命張力試片多破斷於玻璃膠內部與玻璃膠和氧化鉻介面;而經過數個熱機疲勞週期作用，鉻酸鋇生成於接合面外圍，破斷多發生於玻璃膠內部與鉻酸鋇和氧化鉻的介面層。而在還原環境中，試片都破斷於玻璃膠內部與氧化鉻及玻璃膠的介面。在本研究中，試片累積暴露於高溫區段氧化環境及還原環境的時間有限，故環境效應對於熱機疲勞壽命的影響並不顯著。 ;The objective of this study is to investigate thermo-mechanical fatigue (TMF) behavior and relevant fracture mode of a joint between a glass-ceramic sealant and an interconnect steel in solid oxide fuel cell (SOFC) operating environments. The materials used are a GC-9 glass-ceramic sealant developed at the Institute of Nuclear Energy Research (INER) and a commercial Crofer 22 H ferritic stainless steel. TMF test is conducted by applying a cyclic combined thermal and mechanical loading (shear or tensile mode) on the joint. TMF life of shear specimen is increased with a decrease in applied stress level at peak temperature (800 °C) and is dominated by the applied stress level at peak temperature in both oxidizing environment (air) and reducing environment (humidified hydrogen). For applied shear stress of 0.2 joint strength ratio, the sample can run more than 50 TMF cycles. The accumulated time at high temperature (795-800 °C) in TMF test is comparable with the creep rupture time at 800 °C in both oxidizing and reducing environments for shear loading specimens. Based on the observation of fracture surface, fracture mainly occurred at the interface between barium chromate layer and glass-ceramic layer for the shear sample tested in oxidizing environment, while it mainly took place at the interface between chromia layer and glass-ceramic layer in reducing environment. For tensile specimens, TMF life is also increased with a decrease in applied stress level at peak temperature (800 °C) in both oxidizing and reducing environment. However, TMF life under tensile loading is controlled not only by the stress level applied at peak temperature (800 °C) but also by the stress level applied at low temperature (40 °C). It might be due to that brittle glass-ceramic sealant is more sensitive to tensile stress at low temperature. For tensile specimens tested in oxidizing environment with a TMF life of several cycles, fracture occurred in the glass-ceramic layer and at the interface between BaCrO4 chromate layer and Cr2O3 chromia layer on the periphery of joint. For those tested in reducing environment, fracture all took place within the glass-ceramic and at the interface of Cr2O3 chromia layer and glass-ceramic layer. The environmental effect on TMF life is insignificant due to a limited exposure time at high temperature in both given environments.
