A comparative study on the hot corrosion behavior of plasma sprayed Sm/ Gd doped La2Zr2O7/YSZ and Sm and Gd co-doped La2Zr2O7/YSZ coatings

Gd2O3 and Sm2O3 co-doped LZ ceramic ((La0.5Gd0.25Sm0.25)(2)Zr2O7/YSZ) are designed and prepared by atmospheric plasma spraying (APS). It is the aim of this study to investigate the similarities and differences between co-doped sample and mono-doped samples, (La0.5Gd0.5)(2)Zr2O7/YSZ and (La0.5Sm0.5)(2)Zr2O7/YSZ on hot corrosion behaviors exposed to Na2SO4 + V2O5 molten salts. Thermodynamic calculations are used to predict the hot corrosion mechanism before experiments. Characterization and hot corrosion behavior are analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). Results indicate that the main hot corrosion products are composed of rareearth vanadates ((La, Gd)VO4, (La, Sm)VO4 and (La, Gd, Sm)VO4, respectively) and ZrO2. After 10 h of corrosion, the reaction layer evolves into trilayered structure containing Zr-rich layer, V-rich layer and mixed-layer. The formation mechanism is discussed in detail. The co-doped sample exhibits excellent degradation resistance, which can be attributed to the higher entropy value. The formation of the particular trilayered structure occurs earlier in the co-doped sample, which also provides a role in reducing the degradation rate of ceramics.

Automated summary

In this study, Gd2O3 and Sm2O3 co-doped LZ ceramic samples were prepared using atmospheric plasma spraying (APS). The hot corrosion behaviors of the co-doped sample were compared to mono-doped samples. Thermodynamic calculations were used to predict the corrosion mechanism. Characterization and analysis of the corrosion behavior were conducted using various techniques. The co-doped sample exhibited excellent degradation resistance, attributed to its higher entropy value.