Transformation of Electron-Beam Physical Vapor-Deposited 8 wt% Yttria-Stabilized Zirconia Thermal Barrier Coatings
Yttria-stabilized (8.6 mol% YO1.5) zirconia thermal barrier coatings evolve at high temperatures from the “non-transformable,” metastable tetragonal-prime phase in their as-deposited condition to a mixture of the tetragonal and cubic phases. The kinetics of the transformation at 1200° and 1425°C are reported based on X-ray diffraction measurements. Complementary Raman spectroscopy measurements indicate a sharpening of the tetragonal bands at 263 and 465 cm−1 that is attributed to a systematic decrease in disorder of the Y3+ and oxygen vacancies with annealing. No transformation to the monoclinic form of zirconia is observed immediately after high-temperature treatment. However, partial transformation to monoclinic occurs after a prolonged time (months) at room temperature in those samples treated at 1425°C, indicating the development of isothermal martensite.
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Document Type: Research Article
Affiliations: Materials Department, College of Engineering, University of California, Santa Barbara, California 93106-5050
Publication date: 2005-09-01