Solution precursor thermal spraying of gadolinium zirconate for thermal barrier coating

K Leng,A Rincon Romero,F Venturi,I Ahmed,T Hussain

doi:10.1016/j.jeurceramsoc.2021.11.050

K Leng, A Rincon Romero + Show 3 more

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https://doi.org/10.1016/j.jeurceramsoc.2021.11.050

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Abstract

Gadolinium zirconate (GZ) is an attractive material for thermal barrier coatings (TBCs). However, a single layer GZ coating has poor thermal cycling life compared to Yttria Stabilized Zirconia (YSZ). In this study, Solution Precursor High Velocity Oxy-Fuel (SP-HVOF) thermal spray was used to produce a double layer GZ/YSZ TBC and compared the thermal cycling performance with the single layer YSZ TBC. The temperature behaviour of the solution precursor GZ was studied, and single splat tests were carried out to obtain an optimised spray parameter. In thermal cycling tests, the single-layer YSZ reached 20 % failure at 85 ± 5 cycles, whereas the double-layer GZ/YSZ was at 70 ± 15 cycles. The single-layer failed at the topcoat/TGO interface, whereas the double-layer failed at GZ/YSZ interface and topcoat/TGO interface. Moreover, Gd diffusion occurred near the GZ/YSZ interface, resulting in porosities in the GZ layer.

Highlights

IntroductionThermal barrier coatings (TBCs) are widely used in several industrial applications (i.e., automotive, aerospace, power generation) to protect critical components from harsh thermomechanical conditions
Thermal barrier coatings (TBCs) are widely used in several industrial applications to protect critical components from harsh thermomechanical conditions
Cracks are introduced in the system as the phase transformation of Yttria Stabilized Zirco nia (YSZ) is associ ated with 3–5 % of volume change in the microstructure, leading to coating failure [5,8]

Summary

Introduction

Thermal barrier coatings (TBCs) are widely used in several industrial applications (i.e., automotive, aerospace, power generation) to protect critical components from harsh thermomechanical conditions. A significant reduction in the surface temperature of these components, generally in the range between 100 ◦C and 300 ◦C, could be achieved with these coatings [1,2]; this is dependent on the coating’s thickness which is defined by its deposition techniques (i.e., thermal spray, electron beam physical vapour deposition) as well as the functionality (i.e., rotating/static) of the component. YSZ topcoat is limited to provide thermal insulation at a maximum temperature of 1200 ◦C [3,4,5,6,7]. Beyond 1200 ◦C, YSZ will transform from the metastable tetragonal phase (t’) into tetragonal (t) and cubic phases (c).

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