Interaction and infiltration behavior of Eyjafjallajokull, Sakurajima volcanic ashes and a synthetic CMAS containing FeO with/in EB-PVD ZrO2-65 wt% Y2 O3 coating at high temperature

Yttria rich-zirconia thermal barrier coatings (TBCs) with a nominal composition of 65 wt % Y2O3 balanced ZrO2 were deposited by electron-beam physical vapor deposition (EB-PVD) and tested for calcium magnesium-aluminum-silicate (CMAS) infiltration resistance. The infiltration studies were performed with a set of one synthetized CMAS composition and two real volcanic ashes from the Eyjafjallajokull volcano located in Iceland and the Sakurajima volcano located in southern Japan. The coatings were tested at 1250 degrees C for short term (5 min) and long term (intervals from 1 to 20 h). The results indicate a significantly different reaction process for the synthesized CMAS compared with the natural volcanic ashes. The yttria-rich zirconia coatings demonstrate promising results against infiltration by vigorously reacting against the molten glass inducing its crystallization by forming apatite and garnet phases. The formed reaction products effectively sealed the columnar gaps of the TBC and generated a uniform reaction layer that prevented further infiltration. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.