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Title: Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate

Abstract

The presence of vanadium, phosphorus, and sodium impurities in petcoke and coal/petcoke blends used in integrated gasification combined cycle (IGCC) plants warrants a clear understanding of high-temperature material degradation for the development of fuel-flexible gas turbines. In this study, degradation reactions of free-standing air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) in contact with V{sub 2}O{sub 5}, P{sub 2}O{sub 5}, and Na{sub 2}SO{sub 4} were investigated at temperatures up to 1200{sup o}C. Phase transformations and microstructural development were examined using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Molten V{sub 2}O{sub 5} reacted with solid YSZ to form ZrV{sub 2}O{sub 7} at temperatures below 747{sup o}C. However, at temperatures above 747{sup o}C, molten V{sub 2}O{sub 5} reacted with YSZ to form yttrium vanadate (YVO{sub 4}). The formation of YVO{sub 4} led to the depletion of the Y2O{sub 3} stabilizer and deleterious transformation to the monoclinic ZrO{sub 2} phase. In addition, studies on YSZ degradation by Na{sub 2}SO{sub 4} and a Na{sub 2}SO{sub 4}+V{sub 2}O{sub 5} mixture (50-50 mol%) showed that Na{sub 2}SO{sub 4} itself had no effect on the degradation of YSZ. However, in the presence of V{sub 2}O{sub 5} at high temperatures, Na{sub 2}SO{sub 4} forms vanadate compounds having amore » lower melting point such as sodium metavanadate (610{sup o}C), which was found to degrade YSZ by the formation of YVO{sub 4} at a relatively lower temperature of 700{sup o}C. P{sub 2}O{sub 5} was found to react with APS YSZ by the formation of ZrP{sub 2}O{sub 7} at all the temperatures studied. At temperatures as low as 200{sup o}C and as high as 1200{sup o}C, molten P{sub 2}O{sub 5} was observed to react with solid YSZ to yield ZrP{sub 2}O{sub 7}, which led to the depletion of ZrO{sub 2} in YSZ that promoted the formation of the fluorite-cubic ZrO{sub 2} phase.« less

Authors:
; ; ; ;  [1]
  1. University of Central Florida, Orlando, FL (United States)
Publication Date:
OSTI Identifier:
20978431
Resource Type:
Journal Article
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 90; Journal Issue: 11; Journal ID: ISSN 0002-7820
Country of Publication:
United States
Language:
English
Subject:
20 FOSSIL-FUELED POWER PLANTS; COAL; PETROLEUM PRODUCTS; COKE; COAL GASIFICATION; COMBINED-CYCLE POWER PLANTS; GASIFICATION; VANADIUM; PHOSPHORUS; SODIUM; GAS TURBINES; ZIRCONIUM OXIDES; CHEMICAL REACTIONS; VANADIUM OXIDES; SODIUM SULFATES; TEMPERATURE DEPENDENCE; CORROSION

Citation Formats

Mohan, P, Yuan, B, Patterson, T, Desai, V H, and Sohn, Y H. Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate. United States: N. p., 2007. Web. doi:10.1111/j.1551-2916.2007.01941.x.
Mohan, P, Yuan, B, Patterson, T, Desai, V H, & Sohn, Y H. Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate. United States. https://doi.org/10.1111/j.1551-2916.2007.01941.x
Mohan, P, Yuan, B, Patterson, T, Desai, V H, and Sohn, Y H. Thu . "Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate". United States. https://doi.org/10.1111/j.1551-2916.2007.01941.x.
@article{osti_20978431,
title = {Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate},
author = {Mohan, P and Yuan, B and Patterson, T and Desai, V H and Sohn, Y H},
abstractNote = {The presence of vanadium, phosphorus, and sodium impurities in petcoke and coal/petcoke blends used in integrated gasification combined cycle (IGCC) plants warrants a clear understanding of high-temperature material degradation for the development of fuel-flexible gas turbines. In this study, degradation reactions of free-standing air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) in contact with V{sub 2}O{sub 5}, P{sub 2}O{sub 5}, and Na{sub 2}SO{sub 4} were investigated at temperatures up to 1200{sup o}C. Phase transformations and microstructural development were examined using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Molten V{sub 2}O{sub 5} reacted with solid YSZ to form ZrV{sub 2}O{sub 7} at temperatures below 747{sup o}C. However, at temperatures above 747{sup o}C, molten V{sub 2}O{sub 5} reacted with YSZ to form yttrium vanadate (YVO{sub 4}). The formation of YVO{sub 4} led to the depletion of the Y2O{sub 3} stabilizer and deleterious transformation to the monoclinic ZrO{sub 2} phase. In addition, studies on YSZ degradation by Na{sub 2}SO{sub 4} and a Na{sub 2}SO{sub 4}+V{sub 2}O{sub 5} mixture (50-50 mol%) showed that Na{sub 2}SO{sub 4} itself had no effect on the degradation of YSZ. However, in the presence of V{sub 2}O{sub 5} at high temperatures, Na{sub 2}SO{sub 4} forms vanadate compounds having a lower melting point such as sodium metavanadate (610{sup o}C), which was found to degrade YSZ by the formation of YVO{sub 4} at a relatively lower temperature of 700{sup o}C. P{sub 2}O{sub 5} was found to react with APS YSZ by the formation of ZrP{sub 2}O{sub 7} at all the temperatures studied. At temperatures as low as 200{sup o}C and as high as 1200{sup o}C, molten P{sub 2}O{sub 5} was observed to react with solid YSZ to yield ZrP{sub 2}O{sub 7}, which led to the depletion of ZrO{sub 2} in YSZ that promoted the formation of the fluorite-cubic ZrO{sub 2} phase.},
doi = {10.1111/j.1551-2916.2007.01941.x},
url = {https://www.osti.gov/biblio/20978431}, journal = {Journal of the American Ceramic Society},
issn = {0002-7820},
number = 11,
volume = 90,
place = {United States},
year = {2007},
month = {11}
}