Development of Multifunctional Damping Coating Systems for Turbine Engine Components

Research is proposed to investigate the feasibility of modifying the composition and microstructure of thermal barrier coating (TBC) systems to enable enhanced damping capacity while retaining or improving overall system performance. The rotating components, used in gas turbine engines typically operate in severe operating conditions which include high temperatures, loads, vibrations and oxidizing conditions. TBC systems are often used to provide thermal, oxidation and hot corrosion protection to the surface of these components. However, state-of-the-art TBC systems are not currently optimized for damping vibrations stresses which can lead to inefficient engine operation and high cycle fatigue failures. Multiple damping mechanisms exist which could enhance the high temperature damping efficiency of these systems through modifications to their composition, microstructure and architecture. In this work, novel TBC bond coat compositions along with structurally (on the nano-, micro- and macro-scale) modified TBC top coats will be employed to enable multi-functional, damping enhanced TBC systems that are envisioned for use on the low pressure turbine components of gas turbine engines. Such coatings will be deposited using a physical vapor deposition based processing approach which enables enhanced control of the composition and microstructural of TBC layers and a means to apply them onto complex components. BENEFIT: This research is anticipated to result in multifunctional damping coating systems that can reduce vibrational stresses at high temperatures while still providing the required thermal and environmental protection to engine components. The resulting coatings will provide engine designers an additional means to eliminate harmful vibrational stresses, thus, expanding their ability to optimize engine designs for maximized performance. Currently, engine designers of turbine components must assure that there are no resonant frequencies that match the operating points of the airfoil, putting significant constraints on turbine designs operating across a spectrum of speeds and with several different excitations per revolution. The reduction of the vibrational stresses would therefore enable more aerodynamically advanced airfoil designs that may otherwise not be feasible. As a result, damping technologies that can be applied to high cycle fatigue critical components would have a significant impact of engine performance and affordability. These advances will not only benefit military engines which require improvements in engine efficiency and performance, but also commercial and industrial gas turbines. The innovative approach proposed here will also reduce the time and expense for refurbishing and repairing blades during engine overhauls, thus improving military readiness and reducing the cost of maintaining commercial aircraft.