Versatility of potential protective layer material Ti2AlC on resisting CMAS corrosion to thermal barrier coatings

Alleviating calcium-magnesium-alumina-silicate (CMAS) hazard to thermal barrier coatings (TBCs) has attracted increasing attentions. Here, we demonstrate that Ti2AlC is a promising protective layer material for TBCs against CMAS attack, and clarify its corrosion resistance mechanisms. The results reveal that pre-oxidized Ti2AlC has obvious advantages over its non-oxidized counterpart on promoting CMAS crystallization and inhibiting the melt infiltration. Pre-oxidation produces a continuous Al2O3 layer and TiO2 particles on Ti2AlC surface, and Al2O3 reacts with molten CMAS to form anorthite crystals, while TiO2, in the form of either Ti-rich particles or Ti dissolution (there is a content threshold), promotes the crystallization.