Effect of critical plasma spraying parameters on mechanical properties of a novel high-entropy (Y0.2Yb0.2Sc0.2Gd0.2Lu0.2)2Si2O7 environmental barrier coating

Abstract

The aim is to investigate the effect of critical plasma spraying parameter (CPSP) on the mechanical properties and thermal shock resistance of a novel (Y0.2Yb0.2Sc0.2Gd0.2Lu0.2)2Si2O7 high-entropy environmental barrier coating prepared by plasma spraying. Based on a modified Vickers indentation method, the residual stress and fracture toughness of coatings were evaluated, and then the relationship between the CPSP value and thermal shock lifetime of coatings was also established. As a result, the residual compressive stress of (Y0.2Yb0.2Sc0.2Gd0.2Lu0.2)2Si2O7 coating is reduced from -(53.24 ± 6.78) MPa to -(17.97 ± 3.04) MPa with the CPSP value decreases from 1.17kW/Lpm to 0.94kW/Lpm, while the corresponding fracture toughness exhibits an increasing tendency. The combination of higher fracture toughness and lower residual stress result in better thermal shock resistance for the coating, and the longest thermal shock lifetime of (136 ± 16) cycles for the coating deposited with a CPSP value of 0.94kW/Lpm is obtained during thermal shock test at 1350 °C.