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

Shuo Wu,Wenge Li,Fukang Liu,Yuantao Zhao,Weilai Liu,Yanpeng Wu

doi:10.1063/5.0053054

Abstract

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.

Highlights

Various gas turbines are applied to surface ships as power plants, such as cruisers, frigates, and destroyers
Mutter et al.8 found that porosity, elastic modulus, and residual stress evolution were strongly affected by spraying power and spraying distance and were weakly influenced by the feeding rate and cooling
Khan et al.13 found that thermal barrier coating (TBC) prepared by the solution precursor plasma spray (SPPS) technique with a spraying distance of 42 mm exhibited lowest thermal conductivity, and the coating with spraying distance 40 mm displayed high hardness

Summary

Introduction

Various gas turbines are applied to surface ships as power plants, such as cruisers, frigates, and destroyers. Scholars carried out a great deal of research on parameter matching to modify microstructures and improve the performances of 8YSZ TBCs. Mutter et al. found that porosity, elastic modulus, and residual stress evolution were strongly affected by spraying power and spraying distance and were weakly influenced by the feeding rate and cooling. Khan et al. found that TBCs prepared by the solution precursor plasma spray (SPPS) technique with a spraying distance of 42 mm exhibited lowest thermal conductivity, and the coating with spraying distance 40 mm displayed high hardness These excellent works have found some correlations between the parameters and performances, the comprehensive relationship between parameters and microstructures is still not clear due to the complex assembly of various parameters such as power, spraying distance, powder feeding rate, gas speed, and so on. Further explorations into the influences of various parameters on the microstructure and property of the 8YSZ TBCs need to be carried out, which is important and meaningful for performance improving of 8YSZ TBCs

Methods

Results

Conclusion