Electrochemical corrosion of lanthanum chromite and yttrium chromite in coal slag
Lanthanum chromites have long been considered as electrodes for magnetohydrodynamic (MHD) generator channels. These chromites, when doped with divalent ions such as Ca, Mg or Sr, have adequate electronic and electrical conductivity (2), and melting points greater than 2500/sup 0/K. However, above approx. 1850/sup 0/K, selective vapor loss of chromium results in the formation of a La/sub 2/O/sub 3/ phase. The La/sub 2/O/sub 3/ is hydroscopic at room temperature, resulting in a large volume change and loss of mechanical integrity when exposed to H/sub 2/O. The analogous yttrium chromites have thermal and electrical properties similar to that for the lanthanum chromites. Although vapor loss of Cr results in the formation of Y/sub 2/O/sub 3/, this oxide does not hydrate. Corrosion studies of yttrium chromite compositions show that doped YCrO/sub 3/ may be a viable MHD electrode. An electrochemical corrosion study of both magnesium-doped lanthanum and yttrium chromites in synthetic coal slag electrolytes is described. Possible chemical and electrochemical degradation phenomena, as well as the relative rates of corrosion are emphasized.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5977620
- Report Number(s):
- PNL-SA-9195; CONF-810675-5; ON: DE82003846
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanical properties of lanthanum and yttrium chromites
Electrical properties of lanthanum chromite based ceramics in hydrogen and oxidizing atmospheres at high temperatures. Second quarterly report, January-March 1980
Related Subjects
300104* -- MHD Generators-- Duct Engineering & Fluid Dynamics
36 MATERIALS SCIENCE
360205 -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COAL-FIRED MHD GENERATORS
CORROSION
CORROSION RESISTANCE
DIRECT ENERGY CONVERTERS
DOPED MATERIALS
ELECTROCHEMICAL CORROSION
ELECTRODES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MATERIALS
MATERIALS TESTING
MHD GENERATORS
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
SLAGS
TESTING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES