Advances in Coating Design for High-Performance Gas Turbines
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ing Design for HighPerformance Gas Turbines J. R. Nicholls MRS Bulletin / Volume 28 / Issue 09 / September 2003, pp 659 670 Copyright © Materials Research Society 2003 Published online by Cambridge University Press: January 2011 DOI: 10.1557/mrs2003.194
Link to this article: http://journals.cambridge.org/abstract_S0883769400019126 How to cite this article: J. R. Nicholls (2003). Advances in Coating Design for HighPerformance Gas Turbines. MRS Bulletin,28, pp 659670 doi:10.1557/mrs2003.194 Request Permissions : Click here
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Surface engineering is now a key materials technology in the design of future advanced gas-turbine engines. This article focuses on coating systems for hot-gas-path components, which can vary from low-cost aluminide diffusion coatings to the more exotic, and therefore expensive, thermal-barrier coatings. Available coating systems and their relative benefits are reviewed in terms of performance against manufacturing complexity and cost. Future trends in the design of environmental- and thermalprotection coatings are discussed, including the addition of multiple reactive elements, modified aluminide coatings, diffusion-barrier concepts, the design of “smart” corrosionresistant coatings, and the development of structurally modified, low-thermal-conductivity thermal-barrier coatings.
forming a layer of -NiAl on the component surface capable of forming a stable, slow-growing Al2O3 scale (see the sections on Diffusion Coating Processes and Modified Aluminide Coatings for more details). Some 10–12 years later, in the early 1970s,4,8,10–13 overlay coatings were introduced. These offered the capability of custom designing corrosion-resistant alloys—the MCrAlY series of alloys, where M is Ni, Co, or a mixture of Ni and Co—which were overlaid on the superalloy substrates using vacuum deposition, flame/plasma spraying, or, more recently, electroplating technologies, as discussed in the Overlay Coatings section. Most recently, thermal-barrier coatings (TBCs) have been introduced on hot-gaspath components to lower metal surface temperatures. These ceramic overlay coatings work in conjunction with cooling technologies to provide a low-thermalconductivity surface (the thermal barrier) in contact with the hot gases. Plasmasprayed TBCs were first introduced in the mid- to late 1970s on static components. Rotating components were only recently introduced into service, following the development of the electron-beam physical vapor deposition (EB-PVD) process discussed in detail in the section on the Historical Development of Thermal-Barrier Coating Technologies.4,7,11,13–16
Keywords: gas-turbine materials, jet engines, thermal-barrier coatings (TBCs), ultrahigh-temperature coatings.
High-Temperature Surface Protection
Advances in Coating Design for HighPerformance Gas Turbines J.R. Nicholls Abstract
Introduction The drive to improve engine combustion efficiency while reducing em
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