连接体合金在SOFC还原气氛下氧化膜的形成及热应力分析

Formation and Thermal Stress Analysis of Oxide scale of Interconnects Alloy in SOFC Reduction Atmosphere

摘要:

本文针对新型金属连接体材料Fe-Cr-Co合金,通过750°C的循环氧化实验研究其在SOFC阳极气氛(N₂+2%H₂+60%H₂O)下的高温氧化行为,随后基于真实氧化膜和合金的界面微观形貌进行热应力分析。利用X－射线衍射仪(XRD)和配备能谱仪(EDS)的场发射电子显微镜(SEM)对合金氧化膜的相结构和截面形貌以及成分进行表征；结合图像处理和有限元仿真技术模拟合金氧化膜的热应力极值分布。表征结果表明Fe-Cr-Co合金在750°C 阳极中循环氧化600h形成2 μm的氧化膜,其由Fe掺杂的Cr₂O₃内层和MnCr₂O₄外层所构成；仿真分析表明界面受到的最大剪切应力极值分布在波峰与波谷之间的区域,使得该区域的氧化膜容易最先剥落。

Abstract:

In this paper, the high temperature oxidation behavior of a new metal interconnects material Fe-Cr-Co alloy in SOFC anodic atmosphere (N₂+2%H₂+60%H₂O) was studied by cyclic oxidation at 750C, and then the thermal stress analysis was carried out based on the interface morphology of the real oxide and the alloy. The phase structure, cross-sectional morphology and composition of the alloy oxide were characterized by X-ray diffractometer (XRD) and field emission electron microscope (SEM) equipped with energy spectrometer (EDS), and the thermal stress extreme distribution of the alloy oxide was simulated by image processing and finite element simulation technology. The characterization results show that 2 μ m oxide is formed by cyclic oxidation of Fe-Cr-Co alloy in 750C anode for 600h, which is composed of Fe-doped Cr₂O₃ inner layer and MnCr₂O₄ outer layer, and the simulation analysis shows that the maximum shear stress at the interface is distributed in the region between the peak and trough, which makes the oxide in this area easy to peel off first.