Glass Ceramic Seal for Electrochemical Devices

Abstract

Glass-ceramic seals play an important role in the performance of electrochemical devices like solid oxide fuel cell (SOFC), high temperature electrolysis (HTE) and ceramic membrane reactors. In addition to gas tightness and electrical resistivity, a seal material must have a set of thermo-mechanical and chemical properties in order to efficiently seal the SOFC cell components and to maintain performance at elevated temperature over extended operating time. The seal must be stable in oxidizing and reducing atmospheres and withstand thermal cycles between room and the cell typical operating temperature (800 to 900°C). Chemical reaction with the SOFC components should be minimal so as to keep integrity of the seal/cell-interface and prevent degradation in seal reliability over time. In this work, the glass-ceramic seal is discussed for which optimal sintering/crystallization behaviors and thermal stability have been demonstrated. The investigation of the sealant was performed from the point of view of sealing ability and crystallization behavior using Differential Scanning Calorimetry (DSC). The evolution of the seal Coefficient of Thermal Expansion (CTE) has been followed by dilatometric analysis, crystalline phase evolution has been investigated by X-Ray Diffraction (XRD) and the chemical interaction between sealant and cell components has been evaluated by Scanning Electron Microscope (SEM) and Electron Probe Micro Analysis (EPMA).