Corrosion Resistance of Al₂O₃ Coating Prepared by Filtered Cathodic Vacuum Arc for Thermal Barrier Coatings Against CMAS Degradation

To improve the deposit (the main components are CaO, MgO, Al2O3, and SiO2, together referred to as CMAS) corrosion resistance of thermal barrier coatings (TBCs), the filtered cathodic vacuum arc (FCVA) technique was adopted to prepare a dense Al2O3 coating on the surface of TBCs. The wetting behavior and CMAS corrosion resistance of Al2O3-modified TBCs and as-deposited TBCs were compared and analyzed. Results show that the preparation of Al2O3 coating by FCVA technique has no obvious influence on the structure of 7wt% yttria-stabilized zirconia (7YSZ) phase. Besides, the Al2O3-modified TBCs have better comprehensive performance compared with the as-deposited TBCs. Under the CMAS corrosion at 1250 degrees C, the Al2O3 coating effectively restricts the spread of molten CMAS on TBC surface. In addition, the Al2O3 coating fills the gaps between 7YSZ columnar crystals and hinders the infiltration of molten CMAS. It is proved that FCVA method is appropriate to Al2O3 coating preparation in order to improve the CMAS corrosion resistance of TBCs, and the Al2O3 coating and its preparation do not have negative influence on the thermal shock performance of TBCs.