Oxidation behavior of rare earth doped zirconia thermal barrier coating at 1100 °C

Thermal barrier coatings (TBCs) necessitate increased temperatures to enhance the efficiency of gas turbine engines, however, the oxidation of the bonding coat will decrease the lifetime of TBCs. In this study, the 1.0La-2.0Gd-2.0Yb-4.5Y-ZrO₂ (LGYYSZ) and yttria-stabilized zirconia (YSZ) were deposited on Ni-based alloy substrate via atmosphere plasma spray for long-term isothermal oxidation at 1100 °C to investigate oxidation behaviour of LGYYSZ TBCs. The early oxidation stage of LGYYSZ TBC is characterized by a higher oxygen vacancy content, leading to a higher growth rate of TGO compared to YSZ TBC. Following 20 h, the Al₂O₃ layer within the TGO of LGYYSZ coating hindered oxygen ionic diffusion, resulting in a notable slowdown in weight gain comparable to that of the YSZ TBC after the same duration. At 100 h, more significant growth stress caused by the emergence and expansion of an unfavorable multilayer structure of mixed oxides leads to the failure of LGYYSZ coating. The LGYYSZ coating exhibited a slightly higher oxidation weight gain throughout the process than YSZ, which reveals that the parabolic oxidation rate of LGYYSZ was reduced compared to YSZ. Consequently, LGYYSZ demonstrated comparable high-temperature oxidation resistance to YSZ at long-term isothermal oxidation at 1100 °C.