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3651 |
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Preparation and oxidation behavior of air plasma sprayed thermal barrier coatings with a diffusion TiAl3 bond coating on ³-TiAl |
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Lingyan Kong* / Institute of Metal Research, P.R. China Jiqiang Wang / Institute of Metal Research, Chinese Academy of Sciences, China Tiefan Li/ Institute of Metal Research, Chinese Academy of Sciences, China Tianying Xiong/ Institute of Metal Research, Chinese Academy of Sciences, China |
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The thermal barrier coatings comprise a air plasma sprayed yttria-stabilized zirconia ceramic coating on a TiAl3 bond coating which was made by cold sprayed aluminium and subsequent annealing in Ar atmosphere. The TiAl3 coating did not have any cracks and formed a good bond with the top ceramic coating. Oxidation in air at 900 for 500h under quasi-isothermal condition indicated that the thermal barrier coatings exhibited parabolic oxidation kinetics and showed no sign of spallation. Microstructure analysis showed that diffusion occurred between TiAl3 coating and substrate and a thermally grown oxide (TGO) layer formed after oxidation. A small number of protrusions which were mixture of Al2O3 and a small mount of TiO2 interspersed in the vicinity of TGO. Even the existance of these protrusions, the TGO layer generally exhibited an excellent adherence to both TiAl3 coating and ceramic coating and prevented inward oxygen diffusion effectively. Thus the results demonstrated that the thermal barrier coatings largely improved the oxidation resistance of ³-TiAl. |