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1322 |
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Tuesday, June 03, 2008, Auditorium 2 9:30 AM Gasturbines 1 Coatings for mobile and stationary turbines, protection against wear, high temperature corrosion and thermal stresses, clearance control coatings for a better efficiency |
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Contamination free interface for thermal spray deposition of MCrAIY coatings through a new surface preparation named eXclean |
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Carlo Giolli* / Turbocoating SpA, Parma Dario Russo / Turbocoating SpA, Italy Gabriele Rizzi/ Turbocoating SpA, Italy Andrea Scrivani/ Turbocoating SpA, Italy |
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Development of New Surface Preparation of Turbine Components for Deposition of MCrAlY Coatings with Zero Pollution Interface. D. Russoa, A. Scrivania and G. Rizzia aTurbocoating S.p.A., via Mistrali 7, 43010 Rubbiano di Solignano, Italy Abstract The most commonly used structural materials for blades and other high temperature components of gas turbines are nickel superalloys. A TBC protection coating system consist of a top coat of yttria stabilized zirconia and an underlying bond coat, usually MCrAlY. MCrAlY are normally deposited by thermal spray processes: air plasma spray (APS), vacuum plasma spray (VPS), low pressure plasma spray (LPPS) or high velocity oxygen fuel (HVOF). The adhesion between the bond coat and the substrate, and so of the whole thermal barrier system, is strongly dependent on the roughness of the surface. An high roughness means a better adhesion, especially with HVOF thermal spray process where it is a must. Generally the roughness is reached by means of sand blasting with an abrasive media that involve a variable level of surface pollution due to abrasive particles entrapment. The scope of this work was to set up a new surface preparation process in order to obtain a completely pollution free surface with an adequate roughness to be coated afterwards with HVOF or VPS/LPPS thermal spray technology. The results of the tests executed with this process on turbine blades, coated with HVOF system, shown an interface ,coating/base material, pollution free. These results represent an important innovation in the field of turbine components coatings, especially with the advancement of the HVOF thermal spray process, where a clean interface is normally impossible to reach without modify the base material composition (silicon carbide dissolution). |