Electrochemical corrosion of iron-magnesium-alumina spinel (FMAS) in molten potassium salts and coal slag
Iron, magnesium-alumina spinel (FMAS) (0.25 Fe/sub 3/O/sub 4/ . 0.75 MgAl/sub 2/O/sub 4/) has been considered for use as an electrode in magnetohydrodynamic (MHD) generator channels. Predominantly an electronic conductor, FMAS has adequate electrical conductivity (>1 S/m) above 520/sup 0/K. In addition, FMAS can be easily fabricated into a form and sintered in air to >90% theoretical density and has a melting point of 2124 +- 20/sup 0/K. Laboratory tests to measure both the electrochemical and chemical corrosion of FMAS in molten K/sub 2/CO/sub 3/, K/sub 2/SO/sub 4/ and coal slags were developed at the Pacific Northwest Laboratory to evaluate the relative corrosion of FMAS. Under isothermal conditions, a direct electric current was passed between an anode and a cathode through a molten electrolyte. The molten coal slags were synthetic high-calcium, low-iron Montana Rosebud and low-calcium, high-iron Illinois No. 6. Evaluations of electrochemical corrosion were made as functions of current density, temperature, and slag composition. These results were compared to those of FMAS tested without electric current. The corrosion rates and reaction products were investigated by optical microscopy and scanning electron microscopy. Overall, FMAS has too-high an electrochemical corrosion rate to be considered as MHD electrodes in Montana Rosebud coal slag or in systems where only molten potassium salts are present. However, FMAS may be considered for use in high-iron coal slags although the corrosion rates are still quite high even in these slags.
- Research Organization:
- Battelle Pacific Northwest Labs., Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6651706
- Report Number(s):
- PNL-3627
- Country of Publication:
- United States
- Language:
- English
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Electrochemical corrosion of iron-magnesium-aluminum spinel in molten potassium salts and coal slag
Related Subjects
36 MATERIALS SCIENCE
COAL-FIRED MHD GENERATORS
ELECTRODES
MATERIALS TESTING
SLAGS
CORROSIVE EFFECTS
SPINELS
CORROSION
ELECTRIC CONDUCTIVITY
ELECTROCHEMICAL CORROSION
ALUMINIUM OXIDES
CORROSION RESISTANCE
EXPERIMENTAL DATA
IRON OXIDES
MAGNESIUM OXIDES
MATERIALS
MELTING POINTS
MHD CHANNELS
MOLTEN SALTS
POTASSIUM CARBONATES
POTASSIUM SULFATES
TEMPERATURE DEPENDENCE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DIRECT ENERGY CONVERTERS
ELECTRICAL PROPERTIES
INFORMATION
IRON COMPOUNDS
MAGNESIUM COMPOUNDS
MHD GENERATORS
MINERALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
SALTS
SULFATES
SULFUR COMPOUNDS
TESTING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
300103* - MHD Generators- Materials
Components
& Auxiliaries
360205 - Ceramics
Cermets
& Refractories- Corrosion & Erosion