Study of Gd2O3-Doped La2(Zr0.7Ce0.3)2O7 Thermal Barriers for Coating Ceramic Materials for CMAS Resistance

The stability of thermal barrier coating (TBC) materials during service is a prerequisite for the normal operation of aircraft engines. The high-temperature corrosion of CaO–MgO–Al2O3–SiO2 (CMAS) is an important factor that affects the stability of TBCs on turbine blades and causes premature engine failure. For traditional 6-8 YSZ, at temperatures of more than 1200 °C, the thermal insulation performance is significantly reduced, which makes it necessary to find new, alternative materials. La2Zr2O7 has good thermal physical properties; the addition of Ce4+ improves its mechanical properties, while adding Gd2O3 affects its corrosion resistance. Herein, high-temperature corrosion studies of (La1−xGdx)2(Zr0.7Ce0.3)2O7 (L-GZC) (x = 0, 0.3, 0.5, 0.7) ceramic TBC were conducted using CMAS glass at 1250 °C. The results indicate that CMAS rapidly dissolves L-GZC and separates the (La, Gd)8Ca2(SiO4)6O2 apatite phase, ZrO2, and other crystalline phases. These products form a crystalline layer at the contact boundary, which can inhibit further CMAS reactions. Among the coatings examined, the L-GZC ceramic (x = 0.7) exhibits better corrosion resistance, and the penetration depth is <200 μm after high-temperature corrosion at 1250 °C for 5, 10, and 20 h. The failure mechanism and potential risk of CMAS were also analyzed and discussed. The L-GZC ceramic material has good thermal corrosion resistance and is expected to replace the traditional YSZ to better meet the high-temperature working requirements of gas turbines and aircraft engines.