In Situ Diffraction Study of the High-Temperature Decomposition of t-Zirconia Academic Article uri icon

abstract

  • The mechanisms of phase destabilization upon aging of the metastable t phase of yttriastabilized zirconia (YSZ) are poorly understood, despite its broad application in thermal barrier coatings. To provide insight, synchrotron Xray diffraction (XRD) with a quadrupole lamp furnace is used to examine the temperature response, including thermal expansion and phase evolution, of a 9mol% (8wt%) YO1.5 t8YSZ. The thermal expansion of equilibrated YSZ powders ranging from 0 to 18.4mol% YO1.5 is also investigated to better understand the effect of composition on the thermal expansion anisotropy. The T0(c/t) temperature for t8YSZ is estimated to be 1640C. Full decomposition of the t phase into a coherent mixture of a Ylean tetragonal phase (t) and a Yrich cubic phase (c) that coarsen over time is observed at elevated temperatures; however, upon quenching, the t phase reappears in the diffraction profile. This supports our evolving understanding that the t phase observed by XRD in aged samples is a microstructural artifact due to the coherency strain between the t and c phases.

published proceedings

  • JOURNAL OF THE AMERICAN CERAMIC SOCIETY

author list (cited authors)

  • Krogstad, J. A., Gao, Y., Bai, J., Wang, J., Lipkin, D. M., & Levi, C. G.

citation count

  • 44

complete list of authors

  • Krogstad, Jessica A||Gao, Yan||Bai, Jianming||Wang, Jun||Lipkin, Don M||Levi, Carlos G

editor list (cited editors)

  • Sampath, S.

publication date

  • January 2015

publisher