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5418 |
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Thursday, June 08, 2017, Hall 12 4:00 PM Aviation & Power Generation Industry IV |
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Isothermal oxidation behavior of the HVAF-sprayed NiCoCrAlY coating: Effect of surface modification |
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Pimin Zhang / Linköping University, Sweden Esmaeil Sadeghimeresht / Department of Engineering Science, University West, Sweden Ru Lin Peng*/ Linköping University, Sweden Xin-Hai Li/ Siemens Industrial Turbomachinery AB, Swden Sten Johansson/ Department of Management and Engineering, Linköping University, Sweden Shrikant Joshi/ Department of Engineering Science, University West, Sweden |
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NiCoCrAlY coatings are widely used as bond coats for ceramic thermal barrier coatings (TBCs) in industrial gas turbines. High temperature oxidation behavior of the bond coat has a great influence on the performance and lifetime of TBCs. It has been reported that the oxidation rate of HVOF NiCoCrAlY strongly depends on surface modification after the deposition and a uniform alumina scale in the surface treated coatings develops with a considerably lower growth rate compared to the as-sprayed coatings. In this paper, the effect of surface treatment by means of shot-peening, grinding, and vacuum heat treatment methods on the oxidation resistance of HVAF-sprayed NiCoCrlY is studied. Isothermal oxidation at 1000 pC were carried out. The as treated surfaces and the oxide scales developed after the isotheral oxidation are analyzed using the X-Ray diffraction technique and Scanning Electron Microscope to correlate the oxidation behavior of the coatings to their surface conditions. HVAF is a relatively new thermal spray technique for depositing Ni- or Co-based MCrAlY coatings and the purpose of the current work is to improve the oxidation resistance of HVAF-sprayed NiCoCrAlY coatings and their suitability as a bond coat for TBCs. |