Development of electrodes based on yttrium chromites and rare earth doped hafnia for MHD generator applications
Yttrium chromites are being studied as potential high temperature electrodes for MHD. Like lanthanum chromites, the doped yttrium chromites have similar high electrical conductivity, predominantly electronic over a wide temperature range; however, they do not form hydroscopic decomposition products, which cause gross structural degradation. In addition, they exhibit substantially improved resistance to electrochemical attack by slag/seed. The electrical conductivity, thermal diffusivity/conductivity, melting points, thermal expansion, vaporization and electrochemical corrosion for several yttrium chromite compositions are reported and compared with analogous lanthanum chromites. Hafnium oxide containing rare earth additions are also being studied as potential high temperature MHD electrodes. The electrode compositions show a high resistance to electrochemical corrosion in slag/seed. Hafnia-rare earth-M/sub 2/O/sub 3/ oxides can be fabricated with sufficient room temperature electrical conductivity to make them candidates for ceramic-to-metal current leadouts. Electrochemical tests of ceramic current leadout: ceramic electrode couples have been conducted at high temperatures and with high current densities for long periods of time with little interaction between the electrodes and leadouts.
- Research Organization:
- Battelle Pacific Northwest Labs., Richland, WA (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- EY-76-C-06-1830
- OSTI ID:
- 5680800
- Report Number(s):
- PNL-SA-7620; CONF-790640-9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300103* -- MHD Generators-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
360205 -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ADDITIVES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
CONDUCTOR DEVICES
CONNECTORS
CORROSION
CORROSION RESISTANCE
CRYSTAL STRUCTURE
DATA
DATA FORMS
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTROCHEMICAL CORROSION
ELECTRODES
ELEMENTS
EQUIPMENT
EVAPORATION
EXPANSION
GRAPHS
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
INFORMATION
ISOLATED VALUES
MATERIALS
MELTING POINTS
METALS
MHD GENERATORS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RARE EARTHS
SLAGS
SPENT SEED
TABLES
THERMAL CONDUCTIVITY
THERMAL DIFFUSIVITY
THERMAL EXPANSION
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES