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Materials
For DE
PROJECTS
Characterization
of Advanced Ceramics for Industrial and Microturbine Applications
The
development and performance of advanced gas turbine engines is strongly
dependent on the capabilities of the materials utilized to withstand
increasing stress and temperature for long periods of time. Further,
the development of ever improving performance of gas turbines is
strongly dependent on the development of advanced materials. As
both the operating temperatures and durability requirements are
pushed, so an understanding of how the materials will perform is
critical to developmental progress. Ceramics and ceramic composite
materials are of interest to the gas turbine development community
because they offer potential approaches to significant increases
in engine performance. Consequently, these materials are being characterized
both to understand their capabilities and limitations, and to explore
methods to overcome the limitations.
Projects
Oxidation/Corrosion Characterization of Monolithic Si3N4 and EBCs
- Dr.
Karren More
Microstructural
Characterization of CFCCs and Protective Coatings
- Dr. Karren More
Posters
Ceramic Matrix Composites for Industrial Gas Turbines (PDF 848KB)
Oxidation/Corrosion Characterization of Monolithic Si3N4 and EBCs
Contact:
Dr. Karren More
Oak Ridge National Laboratory
Bethel Valley Rd
PO Box 2008
Oak Ridge, TN 37831-6064
(865) 574-7788
morekl1@ornl.gov
Si3N4 is a primary candidate ceramic material for hot section components in microturbines, and thus, the oxidation behavior of Si3N4 exposed to microturbine combustor conditions (elevated water-vapor-pressure and high gas velocities) must be understood. An environmental exposure test facility (Keiser Rig) has been developed at ORNL to expose candidate Si3N4 materials and EBCs to high water vapor pressures representative of the high-temperature, high-pressure environmental typical of industrial gas turbines and microturbines. The objective of this project is to work with ceramic suppliers to expose ceramic materials in the Keiser Rig and characterize the surface recession / corrosion. Currently, there are two promising Si3N4 materials being evaluated in the ORNL Keiser Rigs at very high H2O pressures (~18 atm), NT-154 (produced by Saint Gobain) and SN-282 (produced by Kyocera). The very high H2O pressures are being utilized in these experiments to compensate for low gas velocities in the Keiser Rig (and to induce volatilization) and will enable Si3N4 recession rates and degradation mechanisms to be evaluated.
The EBC evaluation will focus on exposure of the experimental EBCs (usually produced as “stand-alone” coupons, not yet applied to a Si3N4 substrate) to very high water-vapor-pressures in the Keiser Rigs, followed by extensive post-exposure microstructural and mechanical characterization to evaluate compositional stability and volatilization-resistance to rank effectiveness. Coated Si3N4 materials (with the most promising EBCs) will be exposed under the same conditions as the uncoated Si3N4 materials and stand-alone EBCs. The
latest and archived Quarterly Progress Reports
are available in the on-line material in the Reports section.
Recent
Publications: Refer to the Bibliography section for more publications
More,
K., Tortorelli, P., "Verification of an EBC’s Protective
Capability by First-Stage Evaluation in a High Temperature, High
Pressure Furnace, " ASME Technical Paper GT2003-38923, To
be published in the Proceedings of 2003 ASME Turbo Expo Power for
Land, Sea, & Air, June 16-19, 2003, Atlanta GA. (PDF
1.05MB)
Schenk,
B., Strangman, T., Opila, E., Robinson, C., Fox, D., Klemm,
H., Taut, C., More, K., Tororelli, "Oxidation Behavior of Prospective
Silicon Nitride Materials for Advanced Microturbine Applications," 2001-GT-0459,
Proceedings of ASME Turbo Expo 2001, July 4-7, 2001, New
Orleans, LA. (PDF
4.67MB)
More,
K.., Tortorelli, P., Ferber, M., Keiser, J., "Observations
of Accelerated Silicon Carbide Recession by Oxidation at High Water-Vapor
Pressures," J. Am. Ceram. Soc., 83 [1] 211-13 (2000).
(PDF
279KB)
Recent Presentations: Refer to the Bibliography section for more presentations
No current presentations available.
Microstructural
Characterization of CFCCs and Protective Coatings
Contact:
Dr. Karren More
Oak Ridge National Laboratory
Bethel Valley Rd
PO Box 2008
Oak Ridge, TN 37831-6064
(865) 574-7788
morekl1@ornl.gov
Continuous-fiber ceramic matrix composites (CFCCs) have been incorporated into the hot-sections (combustion and hot-gas flow paths) of industrial gas turbines so that these engines can meet strict emission standards by operating at higher temperatures. The objective of this project is to characterize CFCCs and EBC-coated monolithic ceramics that have been exposed to simulated (ORNL’s Keiser Rig) and actual (engine tested) combustion environments. Researchers work with materials manufacturers and coating suppliers to evaluate new or improved materials and optimize the composition and processing materials or coatings.
EBCs have played a critical role in the successful use of CFCCs for this particular application, but there are volatility and stability problems with the current state-of-the-art EBC systems, limiting their life-times. Thus, there remains a critical need for research on the development of more stable EBC compositions for use in combustion (high gas velocity, H2O-containing) environments.
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In collaboration with CFCC manufacturers, EBC developers, and turbine manufacturers, the characterization effort will continue to focus on the evaluation of high temperature materials degradation mechanisms (for CFCC materials and new EBC formulations) in combustion environments in order to improve the understanding of a material’s environmental stability. The work will focus on conducting extremely high water-vapor-pressure exposures in the high Keiser Rigs. In addition, microstructural and mechanical characterization of engine-exposed combustor liners will continue. Laboratory-exposed materials will be compared to actual components from engines to evaluate chemical and microstructural stability to determine degradation modes and failure mechanisms.
The
latest and archived Quarterly Progress Reports
are available in the on-line material in the Reports section.
Recent
Publications: Refer to the Bibliography section for more publications
Tortorelli, P.F. and K.L. More, “Use of Very High Water Vapor Pressures to Evaluate Candidate Compositions for Environmental Barrier Coatings,” paper GT2005-69064 in Proc. 2005 ASME Turbo Expo, ASME International, 2005. (PDF 111KB)
More, K.L., P.F. Tortorelli, T. Bhatia, and G.D. Linsey, “Evaluating the Stability of BSAS-Based EBCs in High Water-Vapor Pressure Environments,” paper GT2004-53863 in Proc. 49th ASME Turbo Expo, ASME International, 2004. (PDF 537KB)
More, K., Tortorelli, P., Walker, L., Kimmel, J, Miriyala, N., Price. J., Eaton, H., Sun, E., Linsey, "Evaluating Environmental Barrier Coatings on Ceramic Matrix Composites After Engine and Laboratory Exposures," ASME GT-2002-30630, Proceedings of ASME Turbo Expos 2002, June 3-6, 2002, Amsterdam, The Netherlands. (PDF 600KB)
Recent Presentations: Refer to the Bibliography section for more presentations
No recent presentations available at this time.
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