Tailoring columnar microstructure of axial suspension plasma sprayed TBCs for superior thermal shock performance

Ashish Ganvir,Shrikant Joshi,Nicolaie Markocsan,Robert Vassen

doi:10.1016/j.matdes.2018.02.011

Ashish Ganvir, Shrikant Joshi + Show 2 more

Open Access

https://doi.org/10.1016/j.matdes.2018.02.011

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Journal: Materials & Design	Publication Date: Feb 4, 2018
Citations: 63	License type: cc-by

Affiliation: University West

Abstract

This paper investigates the thermal shock behavior of thermal barrier coatings (TBCs) produced by axial suspension plasma spraying (ASPS). TBCs with different columnar microstructures were subjected to cyclic thermal shock testing in a burner rig. Failure analysis of these TBCs revealed a clear relationship between lifetime and porosity. However, tailoring the microstructure of these TBCs for enhanced durability is challenging due to their inherently wide pore size distribution (ranging from few nanometers up to few tens of micrometers). This study reveals that pores with different length scales play varying roles in influencing TBC durability. Fracture toughness shows a strong correlation with the lifetime of various ASPS TBCs and is found to be the prominent life determining factor. Based on the results, an understanding-based design philosophy for tailoring of the columnar microstructure of ASPS TBCs for enhanced durability under cyclic thermal shock loading is proposed.

Highlights

Thermal barrier coatings (TBCs) are frequently used to provide thermal and oxidation protection to hot section components of gas turbine⁎ Corresponding author at: Department of Engineering Science, University West, Trollhättan 46186, Sweden.A
Microstructures of TBCs in actual use on hot-section components of aero turbine engines are of both lamellar [9] and columnar [10] type. The former is produced by atmospheric plasma spraying (APS) [9] and the latter by electron beam physical vapor deposition (EBPVD) [10]
This study was aimed at understanding of the role of porosity on the durability of the rather complex columnar Suspension plasma spraying (SPS) TBCs to serve as the basis for tailoring their columnar microstructures to achieve superior TBC performance

Summary

Introduction

Microstructures of TBCs in actual use on hot-section components of aero turbine engines are of both lamellar [9] and columnar [10] type. The former is produced by atmospheric plasma spraying (APS) [9] and the latter by electron beam physical vapor deposition (EBPVD) [10]. APS sprayed lamellar TBCs are known to provide superior thermal insulation due to their inherent porous microstructure [11] whereas the EBPVD TBCs exhibit extended durability due to their strain tolerant columnar structure [3]

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