Low-temperature transformation kinetics of electron-beam deposited 5 wt.% yttria-stabilized zirconia

The transformation kinetics of ZrO2 coatings stabilized with 5.6 mol% YO1.5 (5YSZ), and deposited by electron-beam physical vapor deposition, were studied between room temperature and 600 degrees C using in situ Raman spectroscopy, and are described in the form of a transformation-time-temperature diagram. The coatings were found to be monoclinic (m) at temperatures below 375 degrees C, while above 400 degrees C they transformed to the tetragonal (t) phase. On cooling, the coatings transformed back to monoclinic below similar to 375 degrees C. Between 375 and 400 degrees C, the transformation rates approached zero, indicating that the thermodynamic driving force for the transformation also approaches zero in this temperature range. This provides a direct measurement of the T-0(m-t) temperature for the 5YSZ composition. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.