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2557 |
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Wednesday, September 28, 2011, Saal A 12:15 PM Industrial Gas Turbines 1 |
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Milling and cryo-milling affecting MCrAlY high temperature oxidation mechanism |
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Carlo Giolli / Turbocoating SpA, Italy Andrea Scrivani / Turbocoating SpA, Italy Andrea Giorgetti*/ Turbocoating SpA, Italy Benedetta Bonferroni/ University of Modena, Italy Giovanni Bolelli/ University of Modena, Italy George E. Kim/ Perpetual Technologies Inc., Canada |
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MCrAlY coatings are applied on gas turbine buckets and nozzles by thermal spray techniques (APS, HVOF, LPPS/VPS) as over-layer or as bond coat for TBC systems to improve high temperature corrosion and oxidation resistance of the coated components. The effect of Cryo-Milling and Milling processes has been studied on MCrAlY powders with different chemical compositions in order to evaluate the oxidation mechanism in comparison with the standard one. The chemical and structural characteristics of MCrAlY powders before and after milling processes have been evaluated. HVOF, LPPS and Spark Plasma Sintering techniques have been used to make dense samples to study the oxidation mechanism at high temperature. Oxidation tests have been performed at 1000°C and 1100°C in isothermal condition. The oxidation mechanism has been studied by SEM-EDS system, XRD and Raman Spectroscopy. Milled and cryomilled powders show similar high temperature isothermal oxidation resistance. The milled systems show a high temperature oxidation resistance of about two times greater than standard MCrAlY systems. The different oxidation mechanisms of milled and standard MCrAlYs are presented. |