Degradation of La2Zr2O7 and other novel EB-PVD thermal barrier coatings by CMAS (CaO-MgO-Al2O3-SiO2) and volcanic ash deposits

Corrosive attack of CMAS deposits is studied for a series of advanced EB-PVD thermal barrier coatings including 14YSZ, HfSZ, 29DySZ, CeSZ, La2Zr2O7, and Gd2Zr2O7 upon a 2 hour anneal at 1260 °C in air. Furthermore, the effects of volcanic ash deposits on La2Zr2O7, and Gd2Zr2O7 are studied. A 7YSZ standard coating is employed for benchmarking the resulting microstructures and the coating performances in terms of infiltration depth and chemical reactivity. While all investigated zirconia-based coatings become fully infiltrated by the deposits, the zirconates form crystalline reaction products that prevent complete infiltration. The La2Zr2O7 system is treated as a case study with detailed insight on the newly formed phases via analytical TEM.