"TITLE","AUTHORS","SUBJECT","SUBJECT_RELATED","DESCRIPTION","PUBLISHER","AVAILABILITY","RESEARCH_ORG","SPONSORING_ORG","PUBLICATION_COUNTRY","PUBLICATION_DATE","CONTRIBUTING_ORGS","LANGUAGE","RESOURCE_TYPE","TYPE_QUALIFIER","JOURNAL_ISSUE","JOURNAL_VOLUME","RELATION","COVERAGE","FORMAT","IDENTIFIER","REPORT_NUMBER","DOE_CONTRACT_NUMBER","OTHER_IDENTIFIER","DOI","RIGHTS","ENTRY_DATE","OSTI_IDENTIFIER","PURL_URL"
"Corrosion behaviour of chromium in molten carbonate","Vossen, J P.T.; Makkus, R C [ECN Fossil Fuels, Petten (Netherlands)]; De Wit, J H.W. [Division of Corrosion Technology and Electrochemistry, Laboratory for Materials Science, Delft University of Technology, Delft (Netherlands)]","30 DIRECT ENERGY CONVERSION; 36 MATERIALS SCIENCE; CARBON; DEPOSITION; CHROMIUM; CORROSION; ANODES; CATHODES; CHROMIUM CARBIDES; CHROMIUM OXIDES; CUBIC LATTICES; ELECTRIC POTENTIAL; HEXAGONAL LATTICES; LITHIUM COMPOUNDS; MOLTEN CARBONATE FUEL CELLS; SCALING; VACANCIES; VOLTAMETRY; ALKALI METAL COMPOUNDS; CARBIDES; CARBON COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; CHROMIUM COMPOUNDS; CRYSTAL DEFECTS; CRYSTAL LATTICES; CRYSTAL STRUCTURE; DIRECT ENERGY CONVERTERS; ELECTROCHEMICAL CELLS; ELECTRODES; ELEMENTS; FUEL CELLS; HIGH-TEMPERATURE FUEL CELLS; METALS; NONMETALS; OXIDES; OXYGEN COMPOUNDS; POINT DEFECTS; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; 300503* - Fuel Cells- Materials, Components, & Auxiliaries; 360105 - Metals & Alloys- Corrosion & Erosion","","Corrosion of Cr in molten carbonate was studied using electrochemical techniques in combination with quenching after polarization at fixed potentials. Between -1700 and -1500 mV carbon deposition takes place on the surface. The stationary corrosion product formed on Cr after polarization at -1700 mV is probably chromium carbide. Between -1600 mV and -300 mV a LiCrO[sub 2]-layer is present on the surface of the Cr. The layer is closed between -1600 and -500 mV; at -300 mV the scale is nonadherent and porous. At potentials above -500 mV chromate formation and dissolution takes place. At cathodic potentials point defects (oxygen vacancies) are assumed to be present in the scale, causing a high ionic conductivity. The corrosion rate is expected to be determined by a combination of applied electrode potential and electrical transport properties of the oxide layer. When the potential increases, the oxidation rate of the Cr increases. In the potential region where the point defects are oxidized, scale conductivity decreases and oxidation rate is determined by the transport properties of the scale: the passive properties of the LiCrO[sub 2]-scale have improved. At potentials above -500 mV chromate dissolution takes place. 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. This is probably followed by small changes in the oxide scale. At very cathodic potentials point defects are incorporated in the LiCrO[sub 2]-lattice. This reaction is probably accompanied by the reduction of the instable chromium oxide formed during the preceding anodic scan. Near -1700 mV carbonate decomposes, lithium chromite is reduced and possibly also carbide formation takes place. 14 figs., 13 refs.","","Available from the library of the Netherlands Energy Research Foundation (ECN), P.O. Box 1, 1755 ZG Petten (Netherlands)","Netherlands Energy Research Foundation (ECN), Petten (Netherlands)","","Netherlands","1994-09-01","","English","Technical Report","Special Availability","","","Other Information: This report has been submitted to the Journal of the Electrochemical Society in September 1994","","Medium: X; Size: Pages: (36 p)","","ECN-RX-94-044","","","https://doi.org/","","2008-02-08","6583302",""