Phase Evolution upon Aging of Air-Plasma Sprayed t'-Zirconia Coatings: ISynchrotron X-Ray Diffraction Academic Article uri icon

abstract

  • Phase evolution accompanying the isothermal aging of freestanding airplasma sprayed (APS) 78wt% yttriastabilized zirconia (8YSZ) thermal barrier coatings (TBCs) is described. Aging was carried out at temperatures ranging from 982C to 1482C in air. The hightemperature kinetics of the phase evolution from the metastable t phase into a mixture of transformable Yrich (cubic) and Ylean (tetragonal) phases are documented through ambient temperature Xray diffraction (XRD) characterization. A HollomonJaffe parameter (HJP), T[27+ln(t)], was used to satisfactorily normalize the extent of phase decomposition over the full range of times and temperatures. Comparison to vapor deposited TBCs reveal potential differences in the destabilization mechanism in APS coatings. Furthermore, the lattice parameters extracted from Rietveld refinement of the XRD patterns were used to deduce the stabilizer concentrations of the respective phases, which suggest a retrograde tetragonal solvus over the temperature range studied. In concert with a complementary microstructural study presented in Part II, this effort offers new insights into the mechanisms governing the phase evolution and raises implications for the hightemperature use of 8YSZ ceramics.

published proceedings

  • JOURNAL OF THE AMERICAN CERAMIC SOCIETY

author list (cited authors)

  • Lipkin, D. M., Krogstad, J. A., Gao, Y., Johnson, C. A., Nelson, W. A., & Levi, C. G.

citation count

  • 90

complete list of authors

  • Lipkin, Don M||Krogstad, Jessica A||Gao, Yan||Johnson, Curtis A||Nelson, Warren A||Levi, Carlos G

editor list (cited editors)

  • Troczynski, T.

publication date

  • January 2013

publisher