Doped effect of Gd and Y elements on corrosion resistance of ZrO2 in CMAS melt: First-principles and experimental study

The effects of Gd and Y doping on the corrosion resistance of ZrO2 in CMAS (CaO, MgO, Al2O3, SiO2) melts were investigated via first-principle calculations and experimental investigations. It is found that, although Gd2Zr2O7 with single Gd-doped ZrO2 has the lowest cohesive energy Ecohesive and formation enthalpy Hformation, YSZ(Gd) exhibits the lowest chemical activity with Y and Gd composite doping. The small Griffith's rupture work (W = −3.498 J m−2) is beneficial to the flow of the CMAS melt on the YSZ(Gd) surface. Furthermore, the low Fermi energy and low O and Y electronegativities cause the weakest chemical activity. Additionally, the diffusion coefficients of Y, Zr, and O elements are also decreased through Gd-doping in YSZ. EDS investigations also demonstrate that the CMAS/YSZ(Gd) has the smallest reaction depth (6.65 μm) and the lowest elements penetration ability. Thus, the best corrosion resistance is originated from Y and Gd composite doping in YSZ(Gd) TBCs.