Scandia-stabilized zirconia for resistance to molten vanadate-sulfate corrosion
1989; Elsevier BV; Volume: 39-40; Linguagem: Inglês
10.1016/0257-8972(89)90044-3
ISSN1879-3347
Autores Tópico(s)Thermal and Kinetic Analysis
ResumoFollowing an acid-base theory of ceramic corrosion developed at the Naval Research Laboratory, we have identified scandia as a stabilizer potentially more resistant to molten sulfate-vanadate attack than yttria, the commonly used zirconia stabilizer. This prediction is supported in the present work where, for example, scandia-stabilized zirconia (SSZ) gave no detectable reaction or destabilization after 160 h exposure to 900 °C molten NaVO3, whereas yttria-stabilized zirconia (YSZ) reacted strongly with the NaVO3 (with YVO4 formed) and was extensively destabilized. Other tests confirmed the superior resistance of Sc2O3 over Y2O3 to reaction with both molten sodium vanadate and Na2SO4/SO3. The additional cost for scandia, which is expensive, was calculated to be about $0.15 cm-2 of 10 × 10-3 in (250 μm) coating, or less than half the cost, e.g. for platinum in current platinum-augmented aluminade coatings. Development of molten sulfate- and vanadate-resistant SSZ coatings could give large savings by allowing cheaper, low quality sulfur- and vanadium-containing fuels to be burned in gas turbine or diesel engines.
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