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Research Papers: Gas Turbines: Heat Transfer

# Development of Advanced Thermal Barrier Coatings With Improved Temperature Capability

[+] Author and Article Information
Gregoire Witz

GE Power,
e-mail: gregoire.witz@ge.com

Markus Schaudinn

GE Power,
e-mail: markus.schaudinn@ge.com

Joerg Sopka

GE Power,
Mannheim 65309, Germany
e-mail: joerg.sopka@ge.com

Tobias Buecklers

GE Power,
Birr 5242, Switzerland
e-mail: tobias.buecklers@ge.com

Contributed by the Heat Transfer Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 20, 2016; final manuscript received February 1, 2017; published online March 28, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(8), 081901 (Mar 28, 2017) (6 pages) Paper No: GTP-16-1239; doi: 10.1115/1.4035903 History: Received June 20, 2016; Revised February 01, 2017

## Abstract

Continuously increasing hot gas temperatures in heavy duty gas turbines lead to increased thermal loadings of the hot gas path materials. Thermal barrier coatings (TBCs) are used to reduce the superalloys temperature and cooling air needs. Until now 6–8 wt. % yttria stabilized zirconia (YSZ) is the first choice material for such coatings, but it is slowly reaching its maximum temperature capability due to the phase transformation at high temperature and sintering. New thermal barrier coating material with increased temperature capability enables the next generation of gas turbine with >60% combined cycle efficiency. Such material solutions have been developed through a multistage selection process. In a first step, critical material performance requirements for thermal barrier coating performance have been defined based on the understanding of standard TBC degradation mechanisms. Based on these requirements, more than 30 materials were a preselected and evaluated as potential coating materials. After carefully reviewing their properties both from literature data and laboratory test results on raw materials, five materials were selected for coating manufacturing and laboratory testing. Based on the coating manufacturing trials and laboratory test results, two materials have been selected for engine testing, in a first step in GT26 Birr Test Power Plant and afterward in customer engines. For such tests, the original coating thickness has been increased such to achieve coating surface temperature ∼100 K higher than with a standard thermal barrier coating. Both coatings performed as predicted in both GT26 Birr Test Power Plant and customer engines.

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## Figures

Fig. 1

Average ranking and average ranking standard deviation for 32 candidate TBC materials

Fig. 2

Furnace cyclic test results for five different TBC candidate materials with results for a single-layer 7YSZ samples as a reference

Fig. 3

Burner rig test results for five different TBC candidate materials with results for a single-layer 7YSZ samples as a reference

Fig. 4

Picture of the SEV combustor liner segment coated with New TBC 4 after GT26 Birr Test Power Plant test campaign

Fig. 5

Picture of the SEV combustor liner segment coated with New TBC 1 after GT26 Birr Test Power Plant test campaign

Fig. 7

Borescopic picture of the SHS-A coated with New TBC 1. The coating was smoothly cut through by the LPT blade 1 without bringing any coating or blade tip damages.

Fig. 6

Borescopic picture of the LPT blade 1 coated with New TBC 1 (first blade) and New TBC 4 (second and subsequent blades) at first A-inspection

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