Optimization of process parameters for thermal shock resistance and thermal barrier effects of 8YSZ thermal barrier coatings through orthogonal test

The thermal shock resistance and the thermal barrier effects are the key indices for thermal barrier coating (TBC) performances. The performance optimization of 7∼8 wt. % Y2O3 stabilized ZrO2 (7∼8YSZ) TBCs is a research focus at present. In this work, an orthogonal test was employed to study the relationship between parameters and performances and match process parameters for TBCs preparation. The scanning electron microscope was employed to analyze the microstructures of 8YSZ TBCs. The thermal shock resistance test and thermal barrier effect test were conducted to judge the performances of 8YSZ TBCs. It was found that the process factor had the greatest influences on porosity and elastic modulus was spraying distance and the factor had the greatest influence on bond strength was spraying power. The selected parameters were a spraying distance of 90 mm, an argon flow of 32 L/min, a hydrogen flow of 8 L/min, an electric current of 550 A, a spraying power of 35 kW, a feeding rate of 45 g/min, and a substrate preheating temperature of 373 K. The thermal shock life was ∼100 times under 1173∼298 K, and the thermal barrier temperature of optimized 8YSZ TBCs with thicknesses of 250 and 300 µm was ∼90 and ∼130 K under 1473 K, respectively. Through a comparative study, both thermal shock resistance and thermal barrier effects of 8YSZ TBCs were improved after process parameters’ optimization conducted by this method.