Calcium–magnesium–aluminum‐silicate melt viscosities influenced by lanthanides, yttrium, and zirconium

Abstract Lanthanides (Ln 2 O 3 ) and elements like Zr and Y find application in the highest temperature‐resistant thermal and/or environmental barrier coatings. Such coatings are routinely exposed to silicate particles (e.g., sand, dust, volcanic ash), leading to chemical reactions that degrade the coating. The dissolution of 13.5 wt.% Ln 2 O 3 into a calcium–magnesium–aluminum‐silicate (CMAS) melt leads to a viscosity reduction for the light lanthanides, while viscosity increases toward heavier lanthanides. For Gd, Y, and Zr, various amounts up to 13.5 wt.% (Gd 2 O 3 , Y 2 O 3 , ZrO 2 ) were added to the CMAS melt, showing a tendency of increased viscosity for low concentrations (2.5‐3 wt.%) and a decreasing viscosity for higher values of the added component.