Advanced Bond Coats for Thermal Barrier Coating Systems Based on High Entropy Alloys

Statement of the problem or situation that is being addressed. The availability of ultraclean (near-zero emission), abundant, low-cost domestic energy is critical to providing economic prosperity, strengthening energy independence, and enhancing environmental quality. To accomplish this, it is required to develop a new generation of clean fossil fuel based power systems capable of producing affordable electric power while significantly reducing CO2 emissions to meet environmental standards and help achieve target efficiency goal of 50% or higher. To meet the desired efficiency goals in gas turbine engines, higher temperature operation, as well as, increased durability is anticipated to be required. This is driving the need for the development of advanced coating systems that can operate at very high temperatures, reduce the thermal exposure of metallic turbine engine components, and provide improved durability. Statement of how this problem or situation is being addressed. To help meet this need, an advanced thermal barrier coating (TBC) bond coat materials will be identified through the use of high-entropy alloys (HEA). These alloys are near eqi-atomic combinations of five or more elements having unique combinations of strength, ductility and thermal stability due to their simple underlying lattices (BCC, FCC) and their very high entropy of mixing compared to unwanted intermetallic compounds. Alloys based on these concepts when combined with minor alloying additions may also demonstrate excellent oxidation and hot corrosion resistance making them of high interest as bond coats for TBCs or even as next generation structural alloys for gas turbine components that may not require the application of oxidation resistant coatings. Commercial Applications and Other Benefits. It is envisioned that this work will lead to an economical approach for applying advanced, high temperature capable TBCs onto turbine components. DVTI will license the technology to coating service providers or provide coating services to gas turbine manufacturers. These advanced coatings will enable new turbine designs which enable cleaner, more affordable power generation. In addition to power generation, other commercial sectors including aero gas turbines for the airline industry will benefit. Commercial and non-profit entities utilizing smaller gas turbines to generate power (i.e. hospitals, hotels, refrigerated warehouses) may also benefit. Key Words. High Entropy Alloys, Thermal Barrier Coatings, Gas Turbine Engines, Hot Gas Path Components, Ceramics, High Temperature Materials, Integrated Gasification Combined Cycle Engines, Electron Beam Physical Vapor Deposition, Directed Vapor Deposition Summary for Members of Congress. Higher operating temperatures and improved component durability are required to improve the efficiency of power generation turbine engines utilizing fossil fuels (e.g., coal). Directed Vapor Technologies International and University of Pittsburgh will develop high temperature capable thermal barrier coating systems to protect metallic turbine engine components during increased temperature operation.