Effect of Particle In-Flight Behavior on the Microstructure and Fracture Toughness of YSZ TBCs Prepared by Plasma Spraying

Yanqiu Xiao,Kun Liu,Mingyang Hu,Erzhou Ren

doi:10.3390/coatings8090309

Yanqiu Xiao, Kun Liu + Show 2 more

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https://doi.org/10.3390/coatings8090309

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Abstract

The present study aims to elaborate particle in-flight behavior during plasma spraying and its significance in determining the microstructure and mechanical properties of plasma sprayed yttria partially stabilized zirconia (YSZ) thermal barrier coatings (TBCs). The as-sprayed YSZ coatings were characterized in terms of defects (such as pores, unmelted particles and cracks) and fracture toughness. The results showed that, due to the higher temperature and velocity of in-flight particles in a supersonic atmospheric plasma spraying (SAPS) compared to that of atmospheric plasma spraying (APS), denser coatings were formed leading to a better fracture toughness. The percentage of defects of the microstructure was similar to the temperature and velocity of particles in-flight during plasma spraying. Furthermore, the structural defects had a strong effect on its mechanical behavior. The total defect percentage and fracture toughness in SAPS-TBCs spanned 6.9 ± 0.17%–13.26 ± 0.22% and 2.52 ± 0.06 MPa m1/2–1.78 ± 0.19 MPa m1/2; and 11.11 ± 0.36%–17.15 ± 0.67% and 2.13 ± 0.08 MPa m1/2–1.4 ± 0.12 MPa m1/2 in APS-TBCs.

Highlights

The thermal spraying process (TSP) aims to deposit some special metallic or nonmetallic materials onto the surfaces of pretreated matrices
The complex variables and parameters at the different links of the plasma spraying process mainly contain the structural parameters of spray torch, the production process parameters of the plasma, the size and morphology of the powder, the powder feeding conditions, the in-flight behavior of powder particles in the plasma jet, and the matrix conditions when depositing coatings [5,6,7,8,9,10,11]
The coatings were deposited by two kinds spraying devices, atmospheric spray

Summary

Introduction

The thermal spraying process (TSP) aims to deposit some special metallic or nonmetallic materials onto the surfaces of pretreated matrices. The complex variables and parameters at the different links of the plasma spraying process mainly contain the structural parameters of spray torch, the production process parameters of the plasma, the size and morphology of the powder, the powder feeding conditions, the in-flight behavior of powder particles in the plasma jet, and the matrix conditions when depositing coatings [5,6,7,8,9,10,11] They have a direct influence on the melting state and movement behavior of the particles before impacting the matrix and affect the microstructure of deposited coatings, which further influences the thermodynamic properties (adhesion strength, hardness, Young’s modulus, fracture toughness, and thermal conductivity) and service properties

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Discussion

Conclusion