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5426 |
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Thursday, June 08, 2017, Hall 12 2:00 PM Aviation & Power Generation Industry III |
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Multilayered suspension plasma sprayed thermal barrier coatings for high temperature applications |
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Mohit Gupta* / University West, Sweden Nicolaie Markocsan / University West, Sweden Riston Rocchio-Heller/ Oerlikon Metco, USA Jing Liu/ Oerlikon Metco, USA Brian Callen/ Oerlikon Metco, USA Xin-Hai Li/ Siemens Turbomachinery, Sweden Lars Östergren/ GKN Aerospace, Sweden |
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Improvement in the performance of thermal barrier coating systems (TBCs) is a key objective for further development of gas turbine applications. The material most commonly used as a TBC topcoat is yttria stabilised zirconia (YSZ). However, the usage of YSZ is limited by the operating temperature range which restricts the engine efficiency. Materials such as pyrochlores, perovskites, rare earth garnets, etc. are suitable candidates which could replace YSZ as they usually exhibit lower thermal conductivity and higher phase stability. Columnar microstructures produced by Suspension Plasma Spraying (SPS) are of significant commercial interest as SPS offers a cheaper alternative than the conventionally used Electron Beam Physical Vapour Deposition (EB-PVD) process. The objective of this research work was to investigate different multi-layered TBCs consisting of advanced topcoat materials fabricated by SPS. The single layer topcoat architectures which were investigated were YSZ, and dysprosia stabilised zirconia, while the bilayer topcoat architectures which were investigated were YSZ / YSZ + gadolinium zirconate, YSZ / cerium zirconate, and YSZ / yttria fully stabilised zirconia. All topcoats were deposited with the TriplexPro-210 spray gun manufactured by Oerlikon Metco. The bondcoat material NiCoCrAlY was kept the same for all samples. Lifetime of these samples was examined by thermal cyclic fatigue and thermal shock testing. Microstructure analysis of as-sprayed and failed specimens was performed with scanning electron microscope. The failure mechanism in each case has been discussed in this article. The results show that SPS seems to be a promising route to produce multilayered TBCs for high temperature applications. |