Comparison of electrochemical and surface characterisation methods for investigation of corrosion of bipolar plate materials in molten carbonate fuel cell - Part I. Electrochemical study

The corrosion of bipolar plate and current collector materials in molten carbonate fuel cells (MCFC) was investigated. Tafel extrapolation, linear polarisation resistance, chronopotentiometry and electrochemical impedance spectroscopy (EIS) were used to determine corrosion rates of iron and iron-based alloys in molten carbonate melts for both cathode and anode MCFC environments. During the initial stages, agreement among the methods was good but could have differed after a corrosion layer formed on the surface. The corrosion rate for a fully immersed sample at the open circuit potential seemed to be controlled by external mass transfer of water. Iron-chromium alloys exhibit reasonable corrosion resistance on the cathode side, provided that the chromium concentration exceeds 25%. (C) 1999 Elsevier Science Ltd. All rights reserved.