Member, American Ceramic Society.
Influence of Tetragonality on Tetragonal-to-Monoclinic Phase Transformation during Hydrothermal Aging in Plasma-Sprayed Yttria-Stabilized Zirconia Coatings
Article first published online: 20 DEC 2004
Journal of the American Ceramic Society
Volume 84, Issue 5, pages 1037–1042, May 2001
How to Cite
Yasuda, K., Goto, Y. and Takeda, H. (2001), Influence of Tetragonality on Tetragonal-to-Monoclinic Phase Transformation during Hydrothermal Aging in Plasma-Sprayed Yttria-Stabilized Zirconia Coatings. Journal of the American Ceramic Society, 84: 1037–1042. doi: 10.1111/j.1151-2916.2001.tb00787.x
J. L. Smialek—contributing editor
- Issue published online: 20 DEC 2004
- Article first published online: 20 DEC 2004
- Manuscript No. 189524. Received March 1, 1999; approved December 4, 2000.
- phase transformations;
- zirconia: yttria-stabilized;
The influence of tetragonality, which is defined as the lattice parameter ratio c/a, on the tetragonal-to-monoclinic phase transformation during hydrothermal aging was investigated in yttria-stabilized zirconia coatings. The yttria content was adjusted in the range of 4–8 mass% (denoted as xYZ, where x= 4–8 and YZ represents the yttria-stabilized zirconia). The tetragonality of the zirconia in the as-sprayed coatings was less than that in the powders. To change the tetragonality for each yttria content, the coatings were annealed at 1273 K before aging. Without annealing, the phase transformation was prevented only in 8YZ. When annealing was applied, an increase of the tetragonality (i.e., recovery of the tetragonality) was observed, and transformation during hydrothermal aging was also suppressed in 6YZ. It was concluded that the increase in tetragonality that occurred without a change in the yttria content was suggested to be caused by the lattice relaxation of the tetragonal phase, and this relaxation is believed to cause a reduction of the critical yttria concentration, thus preventing the phase transformation.