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4685 |
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Thursday, May 12, 2016, Room 3E 9:20 AM Characterization & Testing Methods |
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Stress analysis and failure mechanisms of plasma sprayed thermal barrier coatings through spectroscopy technique |
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Jiasheng Yang* / Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Liang Wang / Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Dachuan Li/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Xinghua Zhong/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Huayu Zhao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China Shunyan Tao/ Shanghai Institute of Ceramics, Chinese Academy of Sciences, China |
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Yttria stabilized zirconia coatings were deposited by plasma spraying and heat treated at 1100for 50h, 100h, 150h and 200h in air, respectively. The microstructure and phase composition of coatings were analyzed. Residual stresses in the ceramic topcoat and the thermally grown oxide (TGO) layer before and after thermal exposure were measured using Raman spectroscopy and photoluminescence piezo-spectroscopy techniques, respectively. It was found that the accumulated tensile stress in the as-sprayed topcoat changed to compressive after thermal exposure, and the compressive stress in the topcoat increased with an increase of thermal exposure time up to 150h. The average compressive stresses in the TGO layer were higher than that of the cross-sectional topcoat, and the measured in-plane compressive stress increased firstly and then gradually decreased with increasing exposure time.The local interface geometry strongly affect the nature and evolution of hydrostatic stresses in the TGO. Finally, The crack initiation and propagation in the ceramic topcoat and at the topcoat/TGO/bond coat interface has been discussed with respect to the residual stresses in the plasma-sprayed TBC system. Keywords: Thermal Barrier Coatings (TBCs); Plasma Spraying; Residual Stresses; Raman Spectroscopy; Photoluminescence Piezo-Spectroscopy (PLPS) |