燃料電池連接器合金設計研究-鎳、錳元素對鐵鉻合金熱膨脹性質的影響

Abstract

固態氧化物燃料電池以金屬做為連結板，和陶瓷材料比較起來，具有高導電度、高熱傳、並且可阻隔氣體滲透、並具有良好的機械性質及容易製造等優點；但亦有一些缺點仍待克服，包括高溫時，與其它的電池元件在熱膨脹性質上的差異，以及鉻在高溫時容易揮發等問題。 在之前的研究中於Fe-Cr合金中添加微量元素得到Fe-12Cr與Fe-16Cr是熱膨脹性質表現較佳的鐵鉻二元合金。 實驗配製目標是以肥粒鐵連接器(ferritic interconnect)做為目標，故先用熱力學軟體Thermo-Calc預測合金的結構。 本研究添加鎳與錳以期改善合金性質，並且變換成分的濃度，探討其熱膨脹性質、合金微結構、與高溫電阻。 在熱膨脹性質方面，與YSZ高溫膨脹最相合的是Fe-12Cr-0.5Ni，而高溫電阻性質最好的是Fe-16Cr-1Mn。在本實驗的十種合金中，Fe-12Cr-1Mn為最適合做為SOFC金屬連接器的材料。

The Iron-Chromium alloy metallic interconnect of solid oxide fuel cell(SOFC) has the advantages of high electric conductivity, good thermal conductivity, excellent imperviousness for hydrogen and oxygen to prevent direct oxidant, and good mechanical properties as well as easily to fabricate. However, there are some shortcomings in high-temperature applications; the differences of thermal expansion coefficient with ceramic solid electrolyte of fuel cell will create mismatch between interface, and chromium is apt to volatilize at high temperature, which are still needed to overcome In the previous experiment, we’ve already got that Fe-12Cr and Fe-16Cr are the better composition in thermal expansion behavior. To improve the characters of these two components being SOFC interconnect, we added some micro-element in these alloy. To obtain a good ferritic interconnect, all alloys are BCC in the experiment. Use thermodynamic software Thermo-Calc to make sure the construction of alloys. Choose nickel and manganese as micro-element to improve the character of alloys. We also change the concentration of the micro-elements in the experiment of thermal expansion, microstructure observation, and high temperature resistance. Fe-12Cr-0.5Ni exhibits the best thermal expansion behavior compared to YSZ. Fe-16Cr-1Mn is the best composition in the high temperature resistance experiment. In the ten compositions in the experiment, Fe-12Cr-1Mn is the most suitable composition for SOFC metallic interconnects.