Corrosion of nickel in molten carbonate

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2059276· OSTI ID:6981874

Vossen, J P.T.; Plomp, L ^[1]; Wit, J H.W. de ^[2]

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1. Netherlands Energy Research Foundation ECN, Petten (Netherlands)
2. Delft Univ. of Technology (Netherlands)

Cyclic voltammetry and polarization measurements on nickel under reducing gas atmospheres were performed to investigate the corrosion behavior of nickel as a base metal for molten carbonate fuel-cell separator plate alloys. The anodic reactions observed are oxidation of hydrogen, oxidation of nickel to nickel oxide and to dissolved nickel ions, and oxidation of bivalent nickel to trivalent nickel incorporated in the oxide scale. The cathodic reactions are reduction of trivalent to bivalent nickel to trivalent nickel incorporated in the oxide scale. The cathodic reactions are reduction of trivalent to bivalent nickel in the scale and reduction of bivalent nickel to metallic nickel. During the cathodic scan of the cyclic voltammogram a change in the morphology of the oxide takes place. This is probably due to recrystallization of the oxide. During the cathodic reduction of NiO the scale loses contact from the metal at approximately[minus]1,200 mV; a small crevice is formed between the metal and the scale. The stresses in the loose scale cause cracking. Consequently, the crevice is filled with carbonate. Then nickel oxide dissolves, forming complexes of nickel and carbonate ions. These complexes are reduced to nickel (and carbonate ions) in the crevice. Due to the basic nature of the melt in the crevice, the nickel is oxidized in the following anodic scan, at lower potential ([approximately][minus]1,200 mV) than observed for an oxide-free surface ([approximately][minus]700 mV).

• OSTI ID: 6981874
• Journal Information: Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 141:11; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300503* -- Fuel Cells-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
BATTERY SEPARATORS
CHALCOGENIDES
CHEMICAL REACTIONS
CORROSION
CREVICE CORROSION
DIRECT ENERGY CONVERTERS
DISSOLUTION
ELECTROCHEMICAL CELLS
ELECTROCHEMICAL CORROSION
ELEMENTS
FUEL CELLS
HIGH-TEMPERATURE FUEL CELLS
MATERIALS TESTING
METALS
MOLTEN CARBONATE FUEL CELLS
NICKEL
NICKEL COMPOUNDS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REDOX REACTIONS
TESTING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VOLTAMETRY