Hot corrosion behavior of LaMgAl11O19 ceramic coated with molten CMAS deposits at temperature of 1250 °C in air

Hot corrosion is one of the significant failure mechanisms in hot-section components, especially when molten CaO-MgO-Al2O3-SiO2 (CMAS) deposits attack the thermal barrier coating and facilitate its degradation at elevated temperatures. This work concentrates on the hot corrosion behavior of LaMgAl11O19 ceramic as a promising candidate for TBCs after exposure to CMAS at 1250 °C for 1-16 h in air. The phase constituents and morphologies of the hot corrosion products were investigated by X-ray diffraction and scanning electron microscopy, respectively. Energy-dispersive X-ray spectroscopy was employed for elemental and microstructure analysis. The corrosion products are identified to be CaAl2Si2O8 and Ca(Mg,Al)(Al,Si)2O6 due to the interaction between LaMgAl11O19 ceramic and melt-CMAS by dissolution-reprecipitation. The hot corrosion mechanism was further proposed based on the phase diagram.