Research on Thermal Stability and Properties of Ca3ZrSi2O9 as Potential T/EBC Materials

Yangyang Pan,Xuebin Zheng,Dongdong Liu,Dijuan Han,Bo Liang,Yaran Niu

doi:10.3390/coatings11050583

Yangyang Pan, Xuebin Zheng + Show 4 more

Open Access

https://doi.org/10.3390/coatings11050583

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Abstract

In this study, a new coating material for thermal barrier coating (TBC) or environment barrier coating (EBC) application, Ca3ZrSi2O9 (CZSO), was synthesized and prepared by atmospheric plasma spray (APS) technology. The evolution of the phases and microstructures of the coatings with different thermal-aged were characterized by XRD, XRF, EDS and SEM, respectively. The thermal stability was measured by TG-DTA and DSC. The mechanical and thermal properties, including Vickers hardness (HV), fracture toughness (KIC), thermal conductivity (κ) and coefficient of thermal expansion (CTE) were focused on. It was found that the as-sprayed CZSO coating contained amorphous phase. Crystalline transformation happened at 900–960 °C and no mass changes took place from room temperature (RT) to 1300 °C. The phenomena of microcrack self-healing and composition uniformity were observed during thermal aging. The κ of coating was very low at about 0.57–0.80 W·m−1·K−1 in 200–1200 °C. The combined properties indicated that the CZSO coating might be a potential T/EBC material.

Highlights

With the purpose of improving the efficiency and extending the service life of air or land-based advanced gas turbines, the thermal barrier coating (TBC) are necessary in hot components [1,2].As TBCs materials, the primary property is thermal insulation capacity, that is, low thermal conductivity (κ)
Fleig et al [6] analyzed the influence of the high grain boundaries on the κ, by establishing a brick layer model based on the finite element method, getting a formula for the influence of amorphous phase on κ, as follows
It was observed that the mass loss of the powders happened at about 600–830 ◦C, which was about 24%, and there was an endothermic peak observed

Summary

Introduction

With the purpose of improving the efficiency and extending the service life of air or land-based advanced gas turbines, the TBCs are necessary in hot components [1,2]. MFP and larger spacing resulted in lower κ For this reason, a nanocrystalline yttria partially stabilized zirconia (YSZ) coating was developed, and almost all nanocrystalline. Qiu et al [5] studied the effect of different content SiO2 (amorphous phase) additions on the κ of h-BN-La2O3-Al2O3-SiO2 coatings. They found that the κ was about 5 W/m·K when it contained 30 vol.% SiO2, which was much lower than that of the coating without SiO2 addition. Which κpoly is the κ of polycrystalline YSZ, κYSZ is the κ of single crystal YSZ, n is the grain boundaries’ average number of per unit length, R is the thermal resistance value of this. This research indicates that Ca3ZrSi2O9 might be a potential T/EBCs material for high temperature applications

Powder and Coating Preparation

Thermal-Aging

Thermal–Physical and Microstructure Characterization of CZSO Powder

Thermo-Physics Properties of As-Sprayed and 3 h Aged Coatings