Papers

ICMCTF2008 Session G8: Coatings for Aerospace Applications

Wednesday, April 30, 2008 8:00 AM in Room Royal Palm 1-3

Wednesday Morning

Start	Invited?	Item
8:00 AM		G8-1 Processing and Performance of Ceramic Protective Coatings B.E. Williams, M.E. Harmon, T.R. Stewart (Ultramet) Ultramet is an established leader in manufacturing advanced materials by chemical vapor deposition (CVD) and infiltration (CVI), utilizing a broad variety of refractory metals and ceramics for high temperature and/or extreme environment applications. This technology has been applied to develop a broad range of ceramic protective coatings for aerospace applications. The coatings provide high temperature oxidation protection for both metal and ceramic components, including intricate shapes and textures. The coatings are fully dense and comprise metal carbides, oxides, nitrides, and borides. Layered hafnium carbide/silicon carbide structures offer outstanding oxidation protection up to 1800°C for extended periods and to 2000°C for shorter periods. Yittria-stabilized zirconia thermal barrier coatings have been developed as a low-coat alternative and are also suitable for a broader range of substrates due to the lower deposition temperature. The coatings have been applied to engine and airframe components, fiber interface coatings, and thermal protection systems. The presentation will give an overview of these and other thermal protective coatings developed at Ultramet, focusing on the effects of coating composition and microstructure.
8:40 AM		G8-4 Materials Systems Approach to Meeting Turbine Airfoil Durability Goals: Role of Alloys, Coatings, and Interactions S. Bose (Pratt and Whitney) There is increasing demand on gas turbine engines to improve performance through higher thrust levels at reduced fuel consumption. The performance improvement is often achieved by increasing turbine gas path temperature. This trend strongly influences the choice of materials used in the turbine section. In the past, the requirements were met by choosing materials for individual components that provided the maximum capability. Now the gas path temperature demands have reached such high levels that maximizing individual materials capability is no longer adequate. A "materials systems" approach in the design of the component is now the only option. An example of a component is the turbine blade. In the past, the blade consisted of a nickel base superalloy providing the maximum in creep strength. Increasing gas temperature required internal cooling of the blade. Further increase in temperature required the use of metallic surface coating on the single crystal blade to address environmental degradation through oxidation and corrosion. In today’s engine, however, a nickel base single crystal superalloy blade coated with oxidation resistant metallic coating is not adequate enough. It will still undergo severe oxidation if not melting. Newer and more innovative materials systems approach is now being used including thermally insulating Thermal Barrier Coatings together with advances in heat transfer design. The full paper and presentation will address each element of the systems approach.
9:20 AM		G8-6 Coatings for Polymer Turbine Blades S. Dixit, R. Dixit, M. Chin (Plasma Technology Inc.); K. Hoover (Pratt & Whitney); T. Storage (Wright Patterson Air Force Base) Erosion resistant coatings on high temperature polymer matrix composites are of great interest for aerospace turbine blade applications. In this study, we report evaluation of erosion resistant thermal spray coatings using optical interferometry and conventional weight loss methods in order to compute the net erosion volume loss and erosivity. The erosion tests were carried out at University of Cincinnati high temperature wind tunnel facility. The coated polymer composite coupons were subjected to runway sand and aluminum oxide erodent at room temperature and 600°F at two different angles of incidence.