Papers

ICMCTF2007 Session A1-1A: Coatings to Resist High Temperature Oxidation and Wear

Monday, April 23, 2007 10:00 AM in Room Sunrise

Monday Morning

Start	Invited?	Item
10:00 AM		A1-1-1 An Overview of MCrAlY Coatings for Oxidation Resistance and as TBC Bond Coats R.C. Tucker, Jr. (The Tucker Group, LLC) MCrAlY coatings are one of the most common bond coat systems for thermal barrier coatings and for corrosion protection of gas turbine hot section components. In spite of being in use for decades, research on the understanding of their behavior and the development of new coating compositions continues. This overview considers recent developments in the understanding of the effects of their chemical composition and microstructure on several factors affecting their performance as primary corrosion resistant coatings or as bond coats for TBCs on gas turbine components. Included is consideration of the inter-diffusion of the MCrAlY with the substrate and the subsequent effect on corrosion resistance of the MCrAlY and the thermomechanical properties of the MCrAlY and substrate, consideration of the general corrosion rate of the MCrAlY including the growth of the thermally grown oxide (TGO), and consideration of the performance of the MCrAlY and its TGO on the life of the thermal barrier when used as a bond coat.
10:40 AM		A1-1-3 MCrAlY-Base Multilayer Coatings Fabricated by Sparks Plasma Sintering (SPS) C. Estournes (Cirimat - Ups, France); D. Oquab, D. Monceau (Cirimat - Inpt, France) MCrAlY coatings (where M = Co, Ni or Co/Ni) are widely used on turbine blades and vanes. They are used as oxidation and corrosion resistant overlays or as bond-coats in thermal barrier coatings systems. MCrAlY coatings for high temperature applications are usually fabricated by Plasma Spraying (APS, VPS), Physical Vapor Deposition (PVD), High Velocity Oxyfuel spraying (HVOF) or electrolytic techniques. The present work concerns NiCoCrAlYTa single and multi layered coatings, with aluminization and/or platinum addition, deposited on an AM3 nickel base superalloy using the Sparks Plasma Sintering technique. The first results reported in this paper are promising and open the way to faster development of new coatings with complex structure and composition.
11:00 AM		A1-1-4 Temperature Dependance of Phase Relationships in Different Types of MCrAlY-Coatings J. Toscano (Forschungszentrum Juelich GmbH, Germany); A. Gill (AGH University of Science and Techology, Poland); T. Hüttel, E. Wessel, D. Naumenko, L. Singheiser, W.J. Quadakkers (Forschungszentrum Juelich GmbH, Germany) Phase compositions of different MCrAlY-coatings were studied in the temperature range of 800 to 1100°C. For this purpose free-standing coatings were quenched after different annealing treatments and subsequently extensive characterization of the microstructures using XRD and SEM/EDX was preformed. The experimental results were correlated with the phase equlibria calculations using commercially available software (Thermocalc) and dilatometric measurements of the physical coefficient of thermal expansion. The obtained results demonstrate that the thermal stability of the coating microstructure is sensitive to variations in major elements contents in the range of just a few percent. The obtained results can be used as an indicator of local temperature variation during service of real gas turbine components as well as for prediction of coating interdiffusion behaviour with the superalloy components.