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<p>Bond coats are used to protect the superalloy from oxidation and to act as a bond between the ceramic thermal barrier coating (TBC) layer and the superalloy. During high-temperature exposures, a thermally grown oxide (TGO) layer forms between the bond coat and the topcoat due to oxygen diffusion. Although being fundamental for the substrate oxidation protection, further growth of the TGO creates severe thermal stresses at the bondcoat&#xa0;-&#xa0;topcoat interface, leading to coating failure in the components. This study aimed to investigate the TGO and microstructure evolution of three TBCs with different cold-sprayed bond coat alloys after isothermal heat treatments. The TBCs were heat treated at 1100&#xa0;°C for periods of 12, 25, and 50 hours to study the effects of temperature on the microstructure and phase distribution. The microstructure of heat-treated bond coat alloys was examined using scanning electron microscopy and x-ray diffraction. The TBC with NiCoCrAlTaReY bond coat demonstrated superior performance compared to the other two systems. All TBC systems failed after 50 hours of thermal exposure, as the ceramic topcoat spalled due to crack propagation assisted by thermal stresses.</p>

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Microstructure Evolution and Oxidation Behavior of Thermal Barrier Coating Systems with Various Cold-Sprayed Bond Coats During Isothermal High-Temperature Oxidation Tests

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年11月19日

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  • Carlos R. C. Lima,
  • Genis Clavé,
  • Victor Crespo,
  • Jaume Nin,
  • Sergi Dosta

摘要

Bond coats are used to protect the superalloy from oxidation and to act as a bond between the ceramic thermal barrier coating (TBC) layer and the superalloy. During high-temperature exposures, a thermally grown oxide (TGO) layer forms between the bond coat and the topcoat due to oxygen diffusion. Although being fundamental for the substrate oxidation protection, further growth of the TGO creates severe thermal stresses at the bondcoat - topcoat interface, leading to coating failure in the components. This study aimed to investigate the TGO and microstructure evolution of three TBCs with different cold-sprayed bond coat alloys after isothermal heat treatments. The TBCs were heat treated at 1100 °C for periods of 12, 25, and 50 hours to study the effects of temperature on the microstructure and phase distribution. The microstructure of heat-treated bond coat alloys was examined using scanning electron microscopy and x-ray diffraction. The TBC with NiCoCrAlTaReY bond coat demonstrated superior performance compared to the other two systems. All TBC systems failed after 50 hours of thermal exposure, as the ceramic topcoat spalled due to crack propagation assisted by thermal stresses.