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 deg. 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 deg. C, while above 400 deg. C they transformed to the tetragonal (t) phase. On cooling, the coatings transformed back to monoclinic below ∼375 deg. C. Between 375 and 400 deg. 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