CMAS corrosion behavior of laser-glazed LaYbZrCeO₇/YSZ TBCs: Experimental and first-principles calculation

CaO-MgO-Al₂O₃-SiO₂ (CMAS) corrosion behavior of laser-glazed (LG) LaYbZrCeO₇/YSZ (LYZCO/YSZ) TBCs at 1300 °C was systematically studied utilizing experiment and first-principles calculation. Results indicate that LG-LYZCO coating's equiaxed or columnar grain gaps provide open channels for molten CMAS infiltration. These channels are closed via product Ca₂ ((La,Yb)_xCe_1-x)₈(SiO₄)₆O_6-4x apatite particles under CMAS attack. Compared with as-sprayed YSZ, LZO, and LYZCO coatings, LG-LYZCO coating owns exceptional CMAS resistance (30 min, the reaction layer thickness is just ∼6.4 μm) due to the rapid formation of Ca₂ ((La,Yb)_xCe_1-x)₈(SiO₄)₆O_6-4x. Formation enthalpy of Ca₂ ((La,Yb)_xCe_1-x)₈(SiO₄)₆O_6-4x is merely -(4.500–4.938) eV. Additionally, molten CMAS adheres poorly to the LYZCO surface. Diffusion of (Ca↔RE) and (Si↔RE) is also hard at the CMAS/LYZCO_reactant interface.