Effect of Lanthanum Zirconate on High Temperature Resistance of Thermal Barrier Coatings

Thermal barrier coatings (TBCs) typically have low thermal conductivity and high resistance to oxidation at elevated temperatures. TBCs are used to protect the turbine blades of aircraft engines operating at high temperature. The commonly used YSZ (8 wt% Y2O3-stabilized ZrO2) cannot function at temperatures higher than 1200 degrees C for an extended period of time, which hinders the necessary improvement in the aircraft thrust-to-weight ratio. In this work, thermal barrier coatings consisting of a YSZ ceramic layer and of a lanthanum zirconate (LZ) + YSZ composite structure were prepared on a nickel-based high-temperature substrate using atmospheric plasma spraying. Thermal insulation properties and high temperature oxidation performance of TBCs with single layer structure and double layer structure were compared. The growth mechanism and influencing factors of high-temperature oxidation of thermally grown oxide (TGO) were discussed. The results showed that the LZ had good thermal insulation performance and oxygen isolation compared to the YSZ layer. This performance effectively reduces the growth of TGO in TBCs, thereby delaying the coating failure.