Stress evolution in thermal barrier coatings for rocket engine applications

Martin Bäker,Torben Fiedler,Joachim Rösler

doi:10.1186/s40759-015-0005-2

Martin Bäker, Torben Fiedler + Show 1 more

Open Access

https://doi.org/10.1186/s40759-015-0005-2

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Abstract

Abstract Background Thermal barrier coatings are a promising concept to improve the lifetime of the copper liner of a rocket engine. Due to the high heat fluxes and the large thermal conductivity of copper, coatings have to be designed especially for this application. Methods In this paper, we perform fully thermo-mechanically coupled finite element analyses of a small section of a combustion chamber with a coating system comprising a NiCuCrAl bond coat and a NiCrAlY top coat. Results Heat fluxes are calculated to determine reasonable coating thickness values. Elastic and plastic deformation in the materials is considered to study the stress evolution. A crack model serves to estimate the possibility of vertical cracks propagating through the coating system. Conclusions Several design guidelines are developed from these results that will aid future development of thermal barrier coatings.

Highlights

Thermal barrier coatings are a promising concept to improve the lifetime of the copper liner of a rocket engine
Since this is far beyond the service temperature of engineering materials, the chamber wall is cooled on the inside with liquid hydrogen, and a copper alloy with high thermal conductivity is used so that the surface temperature of the copper wall is exposed to temperatures of about 600 ◦C (Raj et al 2007)
Due to the large thermal stresses caused by the high surface temperature, copper liners can fail at the cooling channel

Summary

Introduction

Thermal barrier coatings are a promising concept to improve the lifetime of the copper liner of a rocket engine. Due to the high heat fluxes and the large thermal conductivity of copper, coatings have to be designed especially for this application. The combustion chamber of rocket engines can be exposed to gas temperatures exceeding 3200 ◦C (Greuel et al 2002) Since this is far beyond the service temperature of engineering materials, the chamber wall is cooled on the inside with liquid hydrogen, and a copper alloy with high thermal conductivity is used so that the surface temperature of the copper wall is exposed to temperatures of about 600 ◦C (Raj et al 2007). One possibility to avoid failure of the copper is to reduce the surface temperature. This can be achieved with thermal barrier coatings (TBCs), using a material of

Methods

Results

Conclusion