Wetting kinetics and corrosion of CMAS and CMAS-NaCl to plasma-sprayed YSZ and Al2O3-YSZ thermal barrier coatings

Transient wetting and corrosion behavior of CMAS and CMAS-NaCl on 7YSZ and Al2O3-YSZ TBCs were investigated at 1250 ℃. NaCl addition decreased the melting point and viscosity of CMAS while improving the dynamic wettability during melt spreading. This intensified melt interactions with TBCs, facilitating CMAS infiltration and coating degradation. The Al2O3 addition to coatings promoted interfacial reactions between glassy melts and TBCs, generating anorthite products. Such reactive wetting decreased spreading velocity and increased contact angles of glassy melts at early interaction stages, but the densely stacked anorthite layer mitigated CMAS and CMAS-NaCl attacks for a longer duration of 10h.