EBC Protection of SiC/SiC Composites in the Gas Turbine Combustion Environment: Continuing Evaluation and Refurbishment Considerations

Author(s):  
Harry E. Eaton ◽  
Gary D. Linsey ◽  
Ellen Y. Sun ◽  
Karren L. More ◽  
Joshua B. Kimmel ◽  
...  

Silicon carbide fiber reinforced silicon carbide composites (SiC/SiC CMC’s) are attractive for use in gas turbine engines as combustor liner materials because the temperature capability allows for reduced cooling. This enables the engine to operate more efficiently and enables the design of very stringent emission goals for NOx and CO. It has been shown, however, that SiC/SiC CMC’s and other silica formers can degrade with time in the high steam environment of the gas turbine combustor due to accelerated oxidation and subsequent volatilization of the silica due to reaction with high pressure water (ref.s 1, 2, 3, & 4). As a result, an environmental barrier coating (EBC) is required in conjunction with the SiC/SiC CMC in order to meet long life goals. Under the U.S. Department of Energy (DOE) sponsored Solar Turbines Incorporated Ceramic Stationary Gas Turbine (CSGT) engine program (ref. 5), EBC systems developed under the HSCT EPM program and improved under the CSGT program have been applied to both SiC/SiC CMC coupons and SiC/SiC CMC combustion liners which have been evaluated in long term laboratory testing and in ground based turbine power generation. This paper discusses the continuing evaluation (see ref. 6) of EBC application to SiC/SiC CMC’s and the results from laboratory and engine test evaluations along with refurbishment considerations.

Author(s):  
Harry E. Eaton ◽  
Gary D. Linsey ◽  
Karren L. More ◽  
Joshua B. Kimmel ◽  
Jeffrey R. Price ◽  
...  

Silicon carbide fiber reinforced silicon carbide composites (SiC/SiC) are attractive for use in gas turbine engines as combustor liner materials, in part, because the temperature capability allows for reduced cooling. This enables the engine to operate more efficiently and to meet very stringent emission goals for NOx and CO. It has been shown, however, that SiC/SiC and other silica formers can degrade with time in the high steam environment of the gas turbine combustor due to accelerated oxidation and subsequent volatilization of the silica due to reaction with high pressure water (ref.s 1 & 2). As a result, an environmental barrier coating (EBC) is required in conjunction with the SiC composite in order to meet long life goals. Under the U.S. Department of Energy (DOE) sponsored Solar Turbines Incorporated Ceramic Stationary Gas Turbine (CSGT) engine program (ref. 3), EBC systems developed under the HSCT EPM program (NASA contract NAS3-23685) were applied to both SiC/SiC composite coupons and SiC/SiC combustion liners which were then evaluated in long term laboratory testing and in ground based turbine power generation, respectively. This paper discusses the application of the EBC’s to SiC/SiC composites and the results from laboratory and engine test evaluations.


Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4214
Author(s):  
Kranthi Kumar Maniam ◽  
Shiladitya Paul

The increased demand for high performance gas turbine engines has resulted in a continuous search for new base materials and coatings. With the significant developments in nickel-based superalloys, the quest for developments related to thermal barrier coating (TBC) systems is increasing rapidly and is considered a key area of research. Of key importance are the processing routes that can provide the required coating properties when applied on engine components with complex shapes, such as turbine vanes, blades, etc. Despite significant research and development in the coating systems, the scope of electrodeposition as a potential alternative to the conventional methods of producing bond coats has only been realised to a limited extent. Additionally, their effectiveness in prolonging the alloys’ lifetime is not well understood. This review summarises the work on electrodeposition as a coating development method for application in high temperature alloys for gas turbine engines and discusses the progress in the coatings that combine electrodeposition and other processes to achieve desired bond coats. The overall aim of this review is to emphasise the role of electrodeposition as a potential cost-effective alternative to produce bond coats. Besides, the developments in the electrodeposition of aluminium from ionic liquids for potential applications in gas turbines and the nuclear sector, as well as cost considerations and future challenges, are reviewed with the crucial raw materials’ current and future savings scenarios in mind.


Author(s):  
Tania Bhatia ◽  
Venkat Vedula ◽  
Harry Eaton ◽  
Ellen Sun ◽  
John Holowczak ◽  
...  

Environmental barrier coatings (EBCs) are being developed for silicon carbide (SiC) based composites and monolithic silicon nitride (Si3N4) to protect against the accelerated oxidation and subsequent silica volatilization in high temperature, high-pressure steam environments encountered in gas turbine engines. While EBCs for silicon carbide (EBCSiC) have been demonstrated in combustor liner applications, efforts are ongoing in the development of EBC systems for silicon nitride (EBCSiN). The challenges of adapting EBCSiC to monolithic Si3N4 are discussed in this paper. Progress in the area of EBCSiN including development and performance during field tests and tests simulating engine conditions are reviewed.


Author(s):  
M. A. Alvin ◽  
B. Gleeson ◽  
K. Klotz ◽  
B. McMordie ◽  
B. Warnes ◽  
...  

The National Energy Technology Laboratory-Regional University Alliance (NETL-RUA) has been developing extreme temperature coating systems that consist of a diffusion barrier coating (DBC), a low-cost wet slurry bond coat, a commercial yttria stabilized zirconia (YSZ) thermal barrier coating (TBC), and an extreme temperature external coating that are deposited along the surface of nickel-based superalloys and single crystal metal substrates. Thermal cyclic testing of these multi-layer coatings was conducted in steam-containing environments at temperatures ranging between 1100–1550°C. This paper discusses the response of these materials during bench-scale testing, and their potential use in advanced H- and J-class land-based gas turbine engines.


Author(s):  
Narendernath Miriyala ◽  
Josh Kimmel ◽  
Jeffrey Price ◽  
Karren More ◽  
Peter Tortorelli ◽  
...  

Under the Ceramic Stationary Gas Turbine (CSGT) Program and the Advanced Materials Program, sponsored by the U.S. Department of Energy (DOE), several silicon carbide/silicon carbide (SiC/SiC) combustor liners were field tested in a Solar Turbines Centaur 50S gas turbine, which accumulated approximately 40000 hours by the end of 2001. To date, five field tests were completed at Chevron, Bakersfield, CA, and one test at Malden Mills, Lawrence, MA. The evaluation of SiC/SiC liners with an environmental barrier coating (EBC) after the fifth field test at Bakersfield (13937 hours) and the first field test at Malden Mills (7238 hours) is presented in this paper. The work at Oak Ridge National Laboratory (ORNL) in support of the field tests was supported by DOE’s Continuous Fiber-Reinforced Ceramic Composite (CFCC) Program.


Author(s):  
Bruno Facchini ◽  
Daniele Fiaschi ◽  
Giampaolo Manfrida

The potential performance of optimized gas-steam combined cycles built around latest-generation gas turbine engines is analyzed, by means of energy/exergy balances. The options here considered are the reheat gas turbine and the H-series with closed-loop steam blade cooling. Simulations of performance were run using a well-tested Modular Code developed at the Department of Energy Engineering of Florence and subsequently improved to include the calculation of exergy destruction of all types (heat transfer, friction, mixing and chemical irreversibilities). The blade cooling process is analyzed in detail as it is recognized to be of capita] importance for performance optimization. The distributions of the relative exergy destruction for the two solutions — both capable of achieving energy/exergy efficiencies in the range of 60% — are compared and the potential for improvement is discussed.


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