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3667 |
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Enhancing high sintering resistance of thermal barrier coating through increased inter-lamella gaps |
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Chang-Jiu Li* / Xi'an Jiaotong University, P.R. China Tao Liu / State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China Guan-Jun Yang/ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China Cheng-Xin Li/ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, China |
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Inter-splat pores in plasma-sprayed ceramic coatings are the key microstructure factor that endows the thermal barrier coatings (TBCs) a low thermal conductivity. Maintaining the lamellar structure features under high temperature is essentially important to keep high thermal insulating performance of TBC. However, many investigations indicate that most of Inter-splat pores heal in a short time when the ceramic coatings are exposed to a high temperature. In this study, 8 wt.% yttria stabilized zirconia (8YSZ) and La2O3/8YSZ freestanding coatings were deposited by atmospheric plasma spraying. La2O3 was also dissolved off in a hydrochloric acid to produce the inter-lamella pores with relatively large gaps. The samples were subjected to a thermal exposure at 1300oC for different durations to investigate the evolution of inter-lamellaar pores with different initial gap sizes. The microstructure feature and fracture surface were characterized by scanning electron microscopy. The thermophysical properties of the coatings after thermal exposure were also examined to investigate the effects of the initial pore gap sizes on sintering process. |