Study on intrinsic mechanical behavior and erosion resistance of multi-rare earth doped La2Zr2O7 coating

Lanthanum zirconate coatings (La2Zr2O7, LZ) have a high Poisson’s ratio and low fracture toughness, making it indescribable for long service life at high temperatures. Rare earth doped lanthanum zirconate (RE-LZ) is an effective way to improve its mechanical properties. In this study, the lanthanum zirconate ceramic coating modified by binary rare earth ((La1/3Gd1/3Y1/3)2Zr2O7, LGYZ; and (La1/3Sm1/3Yb1/3)2Zr2O7, LGYZ) and multi-principal rare earth modified ((La1/5Gd1/5Y1/5Sm1/5Yb1/5)2Zr2O7, HEC-LZ) was studied, aiming to improve the intrinsic mechanical properties of lanthanum zirconate ceramic coating. By comparing the mechanical properties such as fracture toughness, bonding strength, microhardness dissipation parameter, and solid erosion properties of various types of coatings, the results show that compared with binary rare earth modified coatings such as LGYZ and LSYZ, the elastic modulus of the HEC-LZ ceramic coating is reduced by 4.7–6.3%, the microhardness dissipation parameter (MDP) is increased by 4.8–10.2%, and the fracture toughness is increased by 5.2–7.4%. The HEC-LZ ceramic coating showed favorable toughness and crack resistance. Regarding the erosion resistance of the coatings, the ability of RE-LZ coatings is significantly better than that of LZ coatings, and the erosion rate at 45° and 90° is reduced by 44.9–66.0% and 45.7–62.9%, respectively.