Improving the Oxidation Resistance of Fe-Cr-Mn Interconnector of Solid Oxide Electrolyte Fuel Cell with the Addition of Trace Elements

Fe-Cr-Mn alloy is a common material used for the metallic interconnector of solid oxide electrolyte fuel cells (SOFC). However, its high temperature oxidation resistance needs to be strengthened to improve the performance of SOFC. In this study, the effect of trace additions of Ti, Mo, Co and La on the high-temperature behavior of Fe-Cr-Mn alloy was investigated. The composition of Fe-22Cr-2Mn-X (X = Ti, Mo, Co, La) alloys was designed to maintain a bcc structure with the aid of the thermal-calc software. These alloys tended to form Cr-rich oxide in the inner layer and Mn-rich oxide in the outer layer of the specimens after oxidative tests at 850°C, thus reducing the likelihood of chromium oxide evaporation. The experimental results indicated that the addition of Co and La produced better oxidation resistance at high temperatures than Ti and Mo. In addition, the influence of trace elements on electrical resistance of the interconnector material was examined as well.

Characterization and Performance of Glass-Ceramic Sealants for SOECs

Research into hydrogen production using high temperature electrolysis methods has increased significantly in the last few years. Consequently, development of sealing materials has become a major concern particularly for developers of Solid Oxide Electrolyser Cells (SOECs). Suitable sealants for SOECs must operate around 800°C for many hours under reducing and oxidizing conditions. Glass-ceramic compositions based on two glass systems CAS (CaO-Al2O3- SiO2) and SCAS (SrO-CaO-Al2O3-SiO2) with some minor additions (MnO2, B2O3 or TiO2) have been prepared and investigated. Thermal, chemical, and physical properties of the glass ceramics were examined along with the glass crystallization behaviour. Hot Stage Microscopy allowed observation of the sintering and wetting behaviour of glass-ceramics and showed it to be a complex process, significantly affected by glass composition, viscosity, glass transition temperature, crystallization rate and the nature of the crystalline phases formed. The bonding characteristics of parent glasses with ceramic and/or metallic interconnector were observed under air at the cell operating temperature. The results revealed the most suitable glass-ceramic compositions to meet the different criterions and the difficulties involved in formulating such materials.

The Alloy Design of Metallic Interconnector of Solid Oxide Electrolyte Fuel Cell (SOFC)

This study is intended to reduce the difference of thermal expansion coefficient between metallic interconnector and solid electrolyte of SOFC (Solid Oxide Fuel Cell) without sacrificing of electrical conductivity. Fe-Cr alloys have been chosen as candidate materials due to its merit of low cost and high temperature oxidation resistance. Different amount of alloys element and compositions have been varied to optimize the properties by method of alloys design with aid of thermodynamics software Thermal-Cal. Phase diagrams of multi-components alloys have been drawn to predict the possible stable phases formed in the investigated metals. An arc melter and plasma melting furnace were used to melt the investigated alloys. The measurements of thermal expansion coefficients and electrical conductivities are carried out with TMA and ASR resistance instrument. The results indicate that the Fe-10Cr alloy exhibits the smallest thermal expansion coefficient among the alloys, while Fe-16Cr has a lowest electrical resistance .