Microscopic observation of degradation behavior in yttria and ceria stabilized zirconia thermal barrier coatings under hot corrosion

• Published in: Surface & coatings technology Vol. 190; no. 2; pp. 357 - 365
• Main Authors: Park, S.Y., Kim, J.H., Kim, M.C., Song, H.S., Park, C.G.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 21.01.2005; Elsevier
• Subjects: Applied sciences; Ceria stabilized zirconia; Corrosion; Corrosion environments; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Failure mechanism; Hot corrosion; Materials science; Metals. Metallurgy; Nonmetallic coatings; Other topics in materials science; Physics; Production techniques; Surface treatment; Thermal barrier coatings; Yttria stabilized zirconia; Failure mechanism; Thermal barrier coatings; Yttria stabilized zirconia; Hot corrosion; Ceria stabilized zirconia; Thermal barriers; Surface treatments; Stabilized zirconia; Ceramics; Non metal coating; Mechanism
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2004.04.065

In this study, the effects of yttria stabilizer replacement with ceria on hot corrosion properties of thermal barrier coatings (TBCs) have been investigated in microscopic respects. Yttria stabilized zirconia (YSZ; ZrO 2–8 wt.%Y 2O 3) and ceria stabilized zirconia (CSZ; ZrO 2–25 wt.%CeO 2–2.5 wt.%Y 2O 3) thermal barrier coatings (TBCs) were fabricated to have similar microstructures, followed by hot corrosion tests with a NaVO 3 salt at 900 °C. Very dense YSZ TBCs with porosities below 4% were also fabricated in order to investigate the effects of coating defects on hot corrosion behavior. Results revealed that CSZ TBCs were better resistant to hot corrosion environment than YSZ TBCs in terms of phase stability and overall damage by the salt. From studies on microscopic failure behavior, it was found that YSZ and CSZ TBCs showed a different degradation behavior and that coating defects, such as pores, microcracks and splat boundaries, play important roles as effective paths for the salt in hot corrosion. From the present results, a possible microscopic degradation mechanism and effects of coating microstructures for zirconia-based TBCs under hot corrosion are discussed.