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4883 |
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Wednesday, May 11, 2016, Yellow River Hall 11:00 AM Aviation Industry I |
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Influence of bond coat structures on the lifetime of suspension sprayed thermal barrier coatings during thermo-cycling |
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Richard Trache / Fraunhofer IWS Dresden, Germany Kenny Assan/ Dresden Technical University, Germany Filofteia-Laura Toma/ Fraunhofer IWS, Germany Daniel Eichner/ Dresden Technical University, Germany Christoph Leyens*/ Dresden Technical University, Germany |
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Yttria stabilized zirconia based thermal barrier coatings are one of the most promising applications for the suspension spray technology in the gas turbine industry. Different types of microstructures and porosity levels can be achieved by varying the suspension feedstock and spray process parameters. However, the critical location for functional failure is the interface between metallic bond coat and ceramic thermal barrier coating (TBC). Heat cycling, temperature shock and oxidation can result in large-area delamination of the TBC. In this study different types of CoNiCrAlY-bond coats are investigated including conventional APS and EB-PVD bond coats. Additional surface treatment was applied by laser-cladding of (positive) structure elements and by laser-ablation of (negative) texture. These bond coat samples were then coated by suspension plasma spraying using water-based ZrO2-7ma.%Y2O3 suspension. The lifetime of the coating systems was investigated by thermo-cycling at 1100 °C in 1 h cycles. Microstructures were compared before and after thermo-cycling focusing on interface bonding, TBC morphology and crack initiation. The results show that additional laser treatment of the bond coat surface can be beneficial for the coating lifetime. |