Abstract No.:
3669

 Scheduled at:
Friday, May 23, 2014, Hall H2 9:40 AM
Power Generation - Steam


 Title:
Effect of temperature gradient on thermal cyclic lifetime of APS YSZ thermal barrier coatings under gradient thermal cycling test

 Authors:
Chang-Jiu Li* / Xi'an Jiaotong University, P.R. China
Hui Dong / 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

 Abstract:
Gradient thermal cycling test was performed on atmospheric plasma sprayed (APS) yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC) to examine the influence of temperature gradient in ceramic top coat and thermally grown oxide (TGO) thickness on the thermal cyclic lifetime. The TBC system consisted of Inconel 738 substrate, cold-sprayed NiCoCrAlTaY bond coat (BC) and plasma-sprayed YSZ top coat. The YSZ surface was heated to temperatures of 1150oC, 1200oC and 1250oC, respectively, during the test. Every thermal cycling test includes 120s heating and 120s cooling. The temperature gradients across YSZ coating were 150°C, 200°C and 250°C per 250 ¼m thickness, respectively. The thickness of TGO growed to 5.0 ¼m through pre-treatment. Results indicate that the lifetime of APS TBC is significantly affected by temperature gradient that exists through YSZ. The thermal cyclic lifetime prediction model of TBC is established through examining effect of temperature gradient on lifetime of APS TBC. The failure mechanism of the TBC is discussed.

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