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 °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 °C, while above 400 °C they transformed to the tetragonal (t) phase. On cooling, the coatings transformed back to monoclinic below ∼375 °C. Between 375 and 400 °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 T0(m–t) temperature for the 5YSZ composition.