A study of a corrosion-resistant coating for a separator for a molten carbonate fuel cell

Abstract

Abstract The corrosion behaviour of nickel and copper coatings in the current-collector area of separators and a Ni/Al intermetallic compound coating in the wet-seal area of separators for molten carbonate fuel cells is evaluated under immersion in molten carbonate salt. The corrosion-protection effect of nickel and copper coatings on 316L stainless steel is evaluated in an electrochemical half-cell by means of a potentiostatic polarization technique. In addition, the corrosion-protection behaviour of a nickel-coated layer in the anode current-collector area and a Ni/Al-coated layer in the wet-seal area of the separator are studied during operation of a single cell for 10 days. Nickel suffers no observable corrosive attack for up to 500 h in the anode gas atmosphere (H2/CO2). By contrast, nickel and copper exhibit less corrosion resistance than 316L stainless-steel during exposure to the cathode gas atmosphere (CO2/O2). Under a potentiostatic anodic polarization of −1.0 V (versus CO2/O2/Au), nickel-coated 316L stainless-steel displays a lower anodic current density than copper-coated and uncoated 316L stainless-steel. NiAl with a high melting point has better corrosion resistance than other Ni/Al intermetallic compounds. From single cell tests, it is found that nickel and NiAl coatings are efficient for the protection of stainless-steel in the anode area and wet-seal area, respectively.