Abstract No.:	1316
Scheduled at:	Wednesday, June 04, 2008, Room 04 11:00 AM Gasturbines 4 Coatings for mobile and stationary turbines, protection against wear, high temperature corrosion and thermal stresses, clearance control coatings for a better efficiency
Title:	Development and investigation on new composite and ceramic coatings as possible abradable seals
Authors:	Carlo Giolli* / Turbocoating SpA, Parma Ugo Bardi / Dipartimento di Chimica, University of Firenze, Italy Andrea Scrivani/ Turbocoating SpA, Italy Gabriele Rizzi/ Turbocoating SpA, Italy Alessio Fossati/ Dipartimento di Ingegneria Civile, Università di Firenze, Italy Francesca Borgioli/ Dipartimento di Ingegneria Civile, Università di Firenze, Italy K. Partes/ BIAS, Germany T. Seefeld/ BIAS, Germany D. Sporer/ Sulzer Metco (Canada) Inc., Canada
Abstract:	Development and investigation on new composite and ceramic coatings as possible abradable seals. U. Bardia,b, C. Giollia,c, A. Scrivanic, G. Rizzic, F. Borgiolid and A. Fossatid aUniversità di Firenze, Dip. di Chimica, Via della Lastruccia 3, Sesto Fiorentino 50019 Firenze bConsorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Benedetto Varchi 59, 50132 Firenze, Italy cTurbocoating S.p.A., Via Mistrali 7, 43010 Rubbiano di Solignano, Italy dDipartimento di Ingegneria Civile, Università di Firenze, via S. Marta 3, 50139 Firenze, Italy Abstract In order to improve gas turbine performances it is possible to decrease back flow gases in the high temperature combustion region of the turbo machine reducing shroud/rotor gap. Thick and Porous TBC systems and composite CoNiCrAlY/Al2O3 coatings made by Air Plasma Spray (APS) and composite CoNiCrAlY/Graphite coatings made by Laser Cladding were studied as possible high temperature abradable seal on shroud. Oxidation and thermal fatigue resistance of the coatings were assessed by means of isothermal and cyclic oxidation tests. Composite CoNiCrAlY/Al2O3 and CoNiCrAlY/graphite coatings tested for 1000 hours at 1100°C do not show relevant microstructural modifications. The oxidation resistance of new composite coatings satisfies Original Equipment Manufacturer (OEM) specification. Thick and Porous TBC systems passed the thermal fatigue test according to the considered OEM procedures. According to the OEM specification for abradable coatings the hardness evaluation suggests that this kind of coatings must be used with abrasive tipped blades. Thick and porous TBC coating has shown good abradability versus tipped blades.

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