Corrosion behavior of chromium in molten carbonate

Journal Article · Mon Jan 01 04:00:00 EST 1996 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1836388· OSTI ID:201392

Vossen, J P.T.; Makkus, R C ^[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)

The corrosion behavior of Cr in molten carbonate was investigated with electrochemical techniques in combination with quenching after polarization at fixed potentials. Between {minus}1,700 and {minus}1,500 mV carbon deposition takes place on the surface. The stationary corrosion product formed on Cr after polarization at {minus}1,700 mV is probably chromium carbide. Between {minus}1,600 and {minus}300 mV a LiCrO{sub 2}-layer is present on the surface of the Cr. At potentials above approximately {minus}500 mV chromate formation and dissolution take place. When the potential increases, the oxidation rate of the Cr increases due to the larger driving force for oxidation. In the potential region where oxygen vacancies are filled and bivalent chromium ions are oxidized, the conductivity of the scale decreases and the oxidation rate is determined by the transport properties of the scale: the passive properties of the LiCrO{sub 2}-scale have improved. In the anodic scan of a cyclic voltammogram two peaks can be observed, corresponding with the oxidation of point defects, and the formation of instable intermediate chromium oxide. These reactions are accompanied by the formation of lithium chromite. While scanning cathodically, first chromate ions are reduced. At very cathodic potentials trivalent Cr ions are reduced to bivalent Cr ions and point defects, which are incorporated in the LiCrO{sub 2}-lattice, and water is reduced. These reactions may be accompanied by the reduction of the instable chromium oxide formed during the preceding anodic scan. Near {minus}1,700 mV carbonate decomposes, lithium chromite is reduced and possibly carbide formation also takes place.

• Sponsoring Organization: USDOE
• OSTI ID: 201392
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 1 Vol. 143; ISSN 0013-4651; ISSN JESOAN
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
BATTERY SEPARATORS
CHROMATES
CHROMIUM
CHROMIUM CARBIDES
CHROMIUM OXIDES
CORROSION
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
LITHIUM COMPOUNDS
MOLTEN CARBONATE FUEL CELLS
REDOX REACTIONS
VOLTAMETRY