Degradation Behavior of TBC Coatings According to Composition Variation of Bond Coat

Power generation gas turbine engines have been designed to operate at higher to improve efficiency or under a variety of conditions to minimize environmental pollution. This trend requires improved durability and life stability of high-temperature components in the engine. TBCs are essential for protecting high-temperature components of gas turbines, and their performance is greatly influenced by the composition of the ceramic coat. In this study, bond coating powders (Amdry 386-4, Metco 2253A) were applied between the top coating, composed of YSZ, and Substrate of Hastelly X. The growth behavior of the TGO layer in the TBC was investigated with varying bond coating composition. In addition, the relationship between the microstructural change and the oxidation-resistance of TBCs in accordance with their compositions of the bond coats was evaluated by furnace cycling at high temperatures and long-term isothermal oxidation tests. Through this work, the main failure mechanism by thermal fatigue was identified, and the coating's durability and life were evaluated under isothermal conditions by comparing its oxidation resistance at high temperatures. The results offer insights into how bond coating composition affects TBC performance, potentially leading to more advanced coating systems for high-temperature gas turbine applications.