Thermodynamics of the corrosion of chromium in molten carbonates

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5677111

Hsu, H S; DeVan, J H

To define and study the mechanisms that control the corrosion of current collector materials in molten carbonate fuel cells (MCFC), the corrosion of chromium in Li/sub 2/CO/sub 3/-K/sub 2/CO/sub 3/ has been investigated from a thermodynamic point of view. Thermochemical calculations with the SOLGASMIX-PV computer program were used to establish equilibrium phase relationships. This paper considers phase stability diagrams of Cr-Li/sub 2/CO/sub 3/, Cr-K/sub 2/CO/sub 3/, and Cr-(Li,K)/sub 2/CO/sub 3/ systems at 650/sup 0/C. The condensed phases at equilibrium are mapped as functions of log a/sub O/sub 2// and log a/sub CO/sub 2// for the gas mixture O/sub 2/, CO/sub 2/, and Ar at 1.0 atm (1.01 x 10/sup 5/ Pa) total pressure; where a/sub O/sub 2// and a/sub CO/sub 2// are the activities (partial pressures) of O/sub 2/ and CO/sub 2/, respectively. In the system Cr-(Li,K)/sub 2/CO/sub 3/, a mixture of (Li,K)/sub 2/CO/sub 3/ and (Li,K)/sub 2/CrO/sub 4/ should exist under oxidizing environments when log a/sub O/sub 2// > -5.0 and log a/sub CO/sub 2// > -4.6, and a mixture (Li,K)/sub 2/CO/sub 3/ and LiCrO/sub 2/ is stable in reducing atmospheres when log a/sub O/sub 2// < -8.0 and log a/sub CO/sub 2// > -4.6. The concentration of (Li,K)/sub 2/CrO/sub 4/ is dependent on the concentration of (Li,K)/sub 2/CO/sub 3/. The ternary phase boundary of (Li,K)/sub 2/CO/sub 3/-(Li,K)/sub 2/CrO/sub 4/-LiCrO/sub 2/ varies when the concentration of (Li,K)/sub 2/CO/sub 3/ changes. These predicted phase relationships were checked experimentally by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results of TGA and DTA were self-consistent with respect to the reaction products from the calculated phase stability diagrams. 14 refs., 8 figs., 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5677111
• Report Number(s): CONF-850311-14-Draft; ON: DE85011407
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
300505* -- Fuel Cells-- Electrochemistry
Mass Transfer &amp; Thermodynamics
ALKALI METAL COMPOUNDS
ALKALI METALS
ARGON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONATES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHROMATES
CHROMIUM
CHROMIUM COMPOUNDS
CORROSION
DATA
DIFFERENTIAL THERMAL ANALYSIS
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
ELECTRODES
ELEMENTS
ENERGY
FLUIDS
FORMATION FREE ENTHALPY
FREE ENTHALPY
FUEL CELLS
GASES
GRAVIMETRIC ANALYSIS
HIGH-TEMPERATURE FUEL CELLS
INFORMATION
LITHIUM
LITHIUM CARBONATES
LITHIUM COMPOUNDS
METALS
MOLTEN CARBONATE FUEL CELLS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PHASE STABILITY
PHYSICAL PROPERTIES
POTASSIUM
POTASSIUM CARBONATES
POTASSIUM COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
RARE GASES
STABILITY
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL DIAGRAMS
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS