《复合材料 Composites》课程教学资源（学习资料）第五章陶瓷基复合材料_fiber107.pdf_大学文库

E噩≈S Journal of the European Ceramic Society 22(2002)2769-2775 www.elsevier.com/locate/jeurceramsoc Evaluation of CFCC liners with EBC after field testing in a gas turbine Josh Kimmela, * Narendernath Miriyalaa, Jeffrey Pricea, Karren More Peter Tortorelli, Harry Eaton Gary Linsey, Ellen Sun corporated, San Diego, CA, US.A bOak Ridge National Laboratory, Oak Ridge, TN, USA United Technologies Research Center, East Hartford, CT, US/ Received 21 October 2001; received in revised form I February 2002: accepted 25 February 2002 Abstract Under the Ceramic Stationary Gas Turbine(CSGT) Program sponsored by the U. s. Department of Energy(doe), a team led by Solar Turbines Incorporated has successfully designed engines, utilizing silicon carbide/silicon carbide(SiC/Sic)continuous fiber-reinforced ceramic composite(CFCC) combustor liners. Their potential for low NO and CO emissions was demonstrated ht field-engine tests for a total duration of more than 35,000 h. In the first four field tests, the durability of the liners was limited primarily by the long-term stability of Sic in the high steam environment of the gas turbine combustor. Consequently, the need for an environmental barrier coating(EBC) to meet the 30,000-h life goal was recognized. An eBC developed under the National Aeronautics and Space Administration high speed civil transport, enabling propulsion materials program was improved and opti- mized under the CsGT program and applied on the Sic/SiC liners by United Technologies Research Center (UTRC) from the fifth field test onwards. The evaluation of the EBC on SiC/SiC liners after the fifth field test with 13, 937-h at Texaco, Bakersfield, CA, USA is presented in this paper. C 2002 Elsevier Science Ltd. All rights reserved Keywords: Composites; EBC; Electron microscopy; Engine components; SiC 1. Introduction Engine tests were performed at two sites: Texaco (Bakersfield, CA, USA)and Malden Mills(Lawrence In pursuance of its mission to conserve the nations MA, USA). Since July 2000, the field tests are being nergy resources and reduce environmental pollution, performed under the Advanced Materials Program the U.S. Department of Energy, Office of Industrial sponsored by the DOE's Office of Power Technologies Technologies, initiated a program in 1992 to develop SiC/Sic CFCC combustor liners were tested in Solars and demonstrate a ceramic stationary gas turbine for Centaur 50s industrial gas turbine with a nominal power-and-steam cogeneration operation. Solar Tur- power output of 4 MWe. To date, five field tests bines Incorporated (Solar) is the prime contractor on were completed at the Texaco site and one at Malden the program, with participation from major ceramic Mills. A second test at Malden Mills, and a sixth test at component suppliers, research laboratories and two Texaco are currently in progress. I ndustrial end users. The main objective of the program a high rate of SiC recession was exhibited on the is to demonstrate ceramic technology by selective repla- CFCC liners in the first four engine tests due to volati cement of cooled metallic hot-section components by lization of Sic in a combustion environment. In the ceramic parts(blades, nozzles and combustor liners). fourth field test at Texaco, up to 80% of wall thicknes The focus of this paper is on the evaluation of the ebc reduction was exhibited in some areas with localized hot on engine tested Sic/SiC CFCC combustor liners spots, after only 5028 h 1.2 Silicon-based materials such as sic are limited by Corresponding author. Tel: +1-619-544-2819; fax: +1-619-544- their poor environmental durability in combustion environments. SiC is known to perform very well in E-mailaddresskimmel_josh_b@solarturbines.com(.Kimmel).oxidationenvironmentsbyformingaslowgrowing 0955-2219/02/S- see front matter C 2002 Elsevier Science Ltd. All rights reserved. PII:S0955-2219(02)00142-5

Evaluation of CFCC liners with EBC after field testing in a gas turbine Josh Kimmela,*, Narendernath Miriyalaa , Jeffrey Pricea , Karren Moreb, Peter Tortorellib, Harry Eatonc , Gary Linseyc , Ellen Sunc a Solar Turbines Incorporated, San Diego, CA, USA bOak Ridge National Laboratory, Oak Ridge, TN, USA c United Technologies Research Center, East Hartford, CT, USA Received 21 October 2001; received in revised form 1 February 2002; accepted 25 February 2002 Abstract Under the Ceramic Stationary Gas Turbine (CSGT) Program sponsored by the U.S. Department of Energy (DOE), a team led by Solar Turbines Incorporated has successfully designed engines, utilizing silicon carbide/silicon carbide (SiC/SiC) continuous fiber-reinforced ceramic composite (CFCC) combustor liners. Their potential for low NOx and CO emissions was demonstrated in eight field-engine tests for a total duration of more than 35,000 h. In the first four field tests, the durability of the liners was limited primarily by the long-term stability of SiC in the high steam environment of the gas turbine combustor. Consequently, the need for an environmental barrier coating (EBC) to meet the 30,000-h life goal was recognized. An EBC developed under the National Aeronautics and Space Administration high speed civil transport, enabling propulsion materials program was improved and optimized under the CSGT program and applied on the SiC/SiC liners by United Technologies Research Center (UTRC) from the fifth field test onwards. The evaluation of the EBC on SiC/SiC liners after the fifth field test with 13,937-h at Texaco, Bakersfield, CA, USA is presented in this paper. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Composites; EBC; Electron microscopy; Engine components; SiC 1. Introduction In pursuance of its mission to conserve the nation’s energy resources and reduce environmental pollution, the U.S. Department of Energy, Office of Industrial Technologies, initiated a program in 1992 to develop and demonstrate a ceramic stationary gas turbine for power-and-steam cogeneration operation. Solar Turbines Incorporated (Solar) is the prime contractor on the program, with participation from major ceramic component suppliers, research laboratories and two industrial end users. The main objective of the program is to demonstrate ceramic technology by selective replacement of cooled metallic hot-section components by ceramic parts (blades, nozzles and combustor liners). The focus of this paper is on the evaluation of the EBC on engine tested SiC/SiC CFCC combustor liners. Engine tests were performed at two sites: Texaco (Bakersfield, CA, USA) and Malden Mills (Lawrence, MA, USA). Since July 2000, the field tests are being performed under the Advanced Materials Program sponsored by the DOE’s Office of Power Technologies. SiC/SiC CFCC combustor liners were tested in Solar’s Centaur 50S industrial gas turbine with a nominal power output of 4 MWe. To date, five field-engine tests were completed at the Texaco site and one at Malden Mills. A second test at Malden Mills, and a sixth test at Texaco are currently in progress.1 A high rate of SiC recession was exhibited on the CFCC liners in the first four engine tests due to volatilization of SiC in a combustion environment. In the fourth field test at Texaco, up to 80% of wall thickness reduction was exhibited in some areas with localized hot spots, after only 5028 h.1,2 Silicon-based materials such as SiC are limited by their poor environmental durability in combustion environments. SiC is known to perform very well in oxidation environments by forming a slow growing, 0955-2219/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0955-2219(02)00142-5 Journal of the European Ceramic Society 22 (2002) 2769–2775 www.elsevier.com/locate/jeurceramsoc * Corresponding author. Tel.: +1-619-544-2819; fax: +1-619-544- 2830. E-mail address: kimmel_josh_b@solarturbines.com (J. Kimmel)

2770 J. Kimmel et al. /Journal of the European Ceramic Society 22(2002)2769-2775 The rate of SiC recession is, thus, controlled by the volatility rate of silica rather than the oxidation rate of Hole The recession of SiC in high pressure, water vapor environments was quantified at Oak Ridge National Laboratory (ORNL). SiC material was tested in the ORNL high temperature, high steam rig(Keiser rig) at 1200C, 10 atm total and 1. 5 atm water vapor pressures for periods of 500 h at a time. Long term testing has shown that the recession rate is approximately 90 um in 1000 h.6 The SiC recession rates seen in the Keiser rig is onsistent with the engine tests. The need for an ebC to achieve the goal of 30.000-h life The fifth Csgt field test of cfcc liners at Texaco Fig. 1. A hole in the EBC spalled area of the inner liner after the was the first test of EBC protected liners in a gas tur 13.937-h field test. bine. The test was stopped in November 2000 after 13, 937-h of engine operation with 59 starts/stops when lense, adherent silica layer that constitutes a barrier to a small hole was observed in the inner liner during further oxidation. However, combustion environments routine borescope inspection. The maximum CFCC consist of approximately 10% water vapor, as well as liner hot wall temperatures were estimated to be oxygen, carbon dioxide, nitrogen, and hydrogen. Water 1200C. Honeywell Advanced Composites Incorp vapor raises the oxidation rate of Sic by more than an rated(HACD) fabricated the inner and outer liners used order of magnitude. In addition. the silica scale formed in the test. The inner liner was made of a Hi-Nicalon volatilizes in a water vapor environment, leading to SiC-Si composite made by the melt infiltration (MI higher rates of degradation. process. The outer liner was made of an Enhanced Hi Water vapor volatilizes the silica scale primarily by Nicalon/Sic composite made by the che emica vapor the following reaction: infiltration(CVI) process. Boron nitride was used as the fiber/matrix interfacial coating for the inner liner and Sio2(s)+2H20(g)->Si(oh)(g) pyrolitic carbon for the outer liner. Prior to EBC appli cation, a seal coat of Sic was applied on both liners The silica volatilization occurs very quickly and using a chemical vapor deposition process. The seal coat bits a linear rate constant. In conditions such as com- was applied in two steps. An initial seal coat was bustion environments where both SiC oxidation and applied immediately after the fabrication of the two SiO2 volatilization occurs, paralinear kinetics are liners. An additional seal coat was given prior to EBC observed. The overall sample weight change is the sum application, which occurred several months after first of the weight gain due to the growth of the scale and the seal coat application. The EBCs were applied to the gas- weight loss due to volatilization of silica. Over long path surfaces of the two liners by UTRC using a ther periods of time, oxide growth occurs at the same rate as mal spray process. The eBC system consisted of three oxide volatilization so that a constant oxide thickness is layers, each layer approximately 125 um in thickness formed. After a constant oxide thickness is established. silicon mullite and barium strontium aluminum near weight loss and Sic recession rates are observed.(BSaS)was used for the inner liner, and silicon Forward Cold side Forward Hot Side 8 20.3cm 1016cm Fig. 2. Environmental barrier coated Hi-Nicalon/SiC-Si MI inner liner after the 13,937-h field test

dense, adherent silica layer that constitutes a barrier to further oxidation. However, combustion environments consist of approximately 10% water vapor, as well as oxygen, carbon dioxide, nitrogen, and hydrogen. Water vapor raises the oxidation rate of SiC by more than an order of magnitude. In addition, the silica scale formed volatilizes in a water vapor environment, leading to higher rates of degradation. Water vapor volatilizes the silica scale primarily by the following reaction: SiO2(s)+2H2O(g)!Si(OH)4(g) The silica volatilization occurs very quickly and exhibits a linear rate constant. In conditions such as combustion environments where both SiC oxidation and SiO2 volatilization occurs, paralinear kinetics are observed. The overall sample weight change is the sum of the weight gain due to the growth of the scale and the weight loss due to volatilization of silica. Over long periods of time, oxide growth occurs at the same rate as oxide volatilization so that a constant oxide thickness is formed. After a constant oxide thickness is established, linear weight loss and SiC recession rates are observed. The rate of SiC recession is, thus, controlled by the volatility rate of silica rather than the oxidation rate of SiC.35 The recession of SiC in high pressure, water vapor environments was quantified at Oak Ridge National Laboratory (ORNL). SiC material was tested in the ORNL high temperature, high steam rig (Keiser rig) at 1200 C, 10 atm total and 1.5 atm water vapor pressures for periods of 500 h at a time. Long term testing has shown that the recession rate is approximately 90 mm in 1000 h.6 The SiC recession rates seen in the Keiser rig is consistent with the recession rates seen in the first four engine tests. The need for an EBC to achieve the goal of 30,000-h life was apparent. The fifth CSGT field test of CFCC liners at Texaco was the first test of EBC protected liners in a gas turbine. The test was stopped in November 2000 after 13,937-h of engine operation with 59 starts/stops when a small hole was observed in the inner liner during routine borescope inspection. The maximum CFCC liner hot wall temperatures were estimated to be 1200 C. Honeywell Advanced Composites Incorporated (HACI) fabricated the inner and outer liners used in the test. The inner liner was made of a Hi-Nicalon/ SiC-Si composite made by the melt infiltration (MI) process. The outer liner was made of an Enhanced HiNicalon/SiC composite made by the chemical vapor infiltration (CVI) process. Boron nitride was used as the fiber/matrix interfacial coating for the inner liner and pyrolitic carbon for the outer liner. Prior to EBC application, a seal coat of SiC was applied on both liners using a chemical vapor deposition process. The seal coat was applied in two steps. An initial seal coat was applied immediately after the fabrication of the two liners. An additional seal coat was given prior to EBC application, which occurred several months after first seal coat application. The EBCs were applied to the gaspath surfaces of the two liners by UTRC using a thermal spray process. The EBC system consisted of three layers, each layer approximately 125 mm in thickness; silicon, mullite and barium strontium aluminum silicate (BSAS) was used for the inner liner, and silicon, mullite Fig. 1. A hole in the EBC spalled area of the inner liner after the 13,937-h field test. Fig. 2. Environmental barrier coated Hi-Nicalon/SiC-Si MI inner liner after the 13,937-h field test. 2770 J. Kimmel et al. / Journal of the European Ceramic Society 22 (2002) 2769–2775

2772 J. Kimmel et al. Journal of the European Ceramic Society 22(2002)2769-2775 Fig. 6.(a) Thermal diffusivity image of Hi-Nicalon/SiC-Si MI inner liner after the EBC application; (b) digital image of the liner after the after the 13.937-h field test. The low density (red) area in the thermal image corresponds to the ebc-spalled area after the test. loss occurred at the aft end edges and in the middle (from aft to forward)on both liners. The EBC loss in the middle of the liners occurred in areas where fuel injectors were located and, thus, were in the hottest L BSAS areas. It was hypothesized that the EBC loss was due to licon oxidation and volatilization of the silicon-based coating layers. At the aft end edges, it appeared that the top and intermediate layers had spalled off, while the Sio2 silicon layer remained intact. The coating spallation at the aft end edges is due to mechanical interference between the EBC and the metallic combustor that sup ports the liners. Clearly, there was a need to revisit the attachment scheme to minimize/eliminate the EB Fig. 7. Baseline micrograph of the EBC in the aft end of the inner spallation in future engine tests. The combustor design liner after the 13,937-h field test was modified to accomplish this, and the modified design is being used in the sixth field test at Texaco Localized oxidation, manifested by"pinholes,was observed on the outer liner(Fig. 4). The location of inholes correlated with a repeatable pattern of surface asperities from CFCC liner proces- sing steps. However, pinholes were also observed in some locations that did not correlate with processing The pinholes were of different depths, some of them 段念 Mullite+ BSAS extending up 1.5 mm(about half of the liner thickness At one location on the liner the localized oxidation was severe enough to form a pinhole through the wall 2. 2. Nondestructive evaluation of liners Fig 8. Baseline micrograph of the EBC in the aft end of the outer An infrared thermal diffusivity image technique and liner after the 13, 937-h field test an air-coupled ultrasonic method were used to examine the CfCC liners before and after the EBC application correlated with the eBC spalled area after the field test and after the conclusion of the field test. The non-(Fig 6). Thus, it appears that nde can be successfully destructive evaluation (NDE) was performed by ANL. used as a screening tool to select EBC liners for engine Thermal diffusivity images indicated low diffusivity use. 7 (debonding) of the EBC layers on several locations where EBC appeared to be intact to visual observation 23. Microstructural evaluation at the end of the test(Fig. 5). For the inner liner, NDE images after the EBC application showed a significant Representative microstructures of the eBC applied to area of low density, the area and geometry of which the aft end of the inner and outer liner after the 13, 937-h

loss occurred at the aft end edges and in the middle (from aft to forward) on both liners. The EBC loss in the middle of the liners occurred in areas where fuel injectors were located and, thus, were in the hottest areas. It was hypothesized that the EBC loss was due to silicon oxidation and volatilization of the silicon-based coating layers. At the aft end edges, it appeared that the top and intermediate layers had spalled off, while the silicon layer remained intact. The coating spallation at the aft end edges is due to mechanical interference between the EBC and the metallic combustor that supports the liners. Clearly, there was a need to revisit the attachment scheme to minimize/eliminate the EBC spallation in future engine tests. The combustor design was modified to accomplish this, and the modified design is being used in the sixth field test at Texaco. Localized oxidation, manifested by ‘‘pinholes’’, was observed on the outer liner (Fig. 4). The location of many of these pinholes correlated with a repeatable pattern of surface asperities from CFCC liner processing steps. However, pinholes were also observed in some locations that did not correlate with processing. The pinholes were of different depths, some of them extending up 1.5 mm (about half of the liner thickness). At one location on the liner, the localized oxidation was severe enough to form a pinhole through the wall. 2.2. Nondestructive evaluation of liners An infrared thermal diffusivity image technique and an air-coupled ultrasonic method were used to examine the CFCC liners before and after the EBC application and after the conclusion of the field test. The nondestructive evaluation (NDE) was performed by ANL. Thermal diffusivity images indicated low diffusivity (debonding) of the EBC layers on several locations where EBC appeared to be intact to visual observation at the end of the test (Fig. 5). For the inner liner, NDE images after the EBC application showed a significant area of low density, the area and geometry of which correlated with the EBC spalled area after the field test (Fig. 6). Thus, it appears that NDE can be successfully used as a screening tool to select EBC liners for engine use.7 2.3. Microstructural evaluation Representative microstructures of the EBC applied to the aft end of the inner and outer liner after the 13,937-h Fig. 6. (a) Thermal diffusivity image of Hi-Nicalon/SiC-Si MI inner liner after the EBC application; (b) digital image of the liner after the after the 13,937-h field test. The low density (red) area in the thermal image corresponds to the EBC-spalled area after the test. Fig. 7. Baseline micrograph of the EBC in the aft end of the inner liner after the 13,937-h field test. Fig. 8. Baseline micrograph of the EBC in the aft end of the outer liner after the 13,937-h field test. 2772 J. Kimmel et al. / Journal of the European Ceramic Society 22 (2002) 2769–2775

J. Kimmel et al. /Journal of the European Ceramic Society 22(2002)2769-2775 2773 Middle Fig. 9. Recession of BSAS top layer EBC on the inner liner after 13, 937-h field test. engine test are presented in Figs. 7 and 8, respectively. A three-layer EBC that was applied to both liners con sisted of a BSAs top layer, a mullite or mulli te +BSAs intermediate layer, and a silicon bottom layer. A layer of silica was formed during the engi test due to oxidation of the silicon layer. The EBC on 妈点 he inner liner consisted of silicon (90-125 um), silica (60-100um), mullite(75-100um), and bsas(150-200 Hm). On the outer liner, the EBC consisted of silicon (75-140 um), silica(25-60 Hm), mullite+ BSAS (175- 225m), and bsas(175-200um). The three-layer EBC system used on the outer liner performed better than on the inner liner. The addition Fig 10. EBC after recession of BSAS top layer on the outer liner after 13.937-h field test. The EBC is still protective even after some recession of BSAS to mullite in the intermediate layer minimized/ of the BSAS top layer reduced cracks and porosity in that layer, resulting in reduced oxidation of the silicon layer, and thus better protection of the liner. In addition, separation at the interface of the mullite intermediate layer and the silica layer was greatly reduced with the addition of bSAs lumina These results are consistent with Keiser rig testing results A mullite BSAs intermediate layer was used to ,alumina coat the SiC/Sic liners used in first two Malden Mills and the sixth Texaco engine tests. Recession of the Bsas top layer, which was not observed in over 5000-h Keiser rig tests at ORNL was observed on both liners exposed to engine environ- ment(Fig. 9). The main difference between the Keiser rig and combustion environment is the gas velocity Velocity plays an important role in the volatilization of silica. 2 The Keiser rig operates at low velocities, less Fig. Il. Mullite phase separation of the intermediate layer into silica and alumina phases. Silica volatilization within the mullite layer leads than 1 cm/s, versus gas velocities on the order of 85 m/s to porosity in the engine. The low velocity in the Keiser rig does not allow for complete volatilization, and recession results was consistent with 6500 h of Keiser Rig testing at are reported based upon oxidation depth. Fortunately, 1200oC. In order to reduce the bsas recession in future even after partial BSAS recession, the EBC was still engine tests, either its thickness can be increased or the protective(Fig. 10). A uniform layer of approximately composition modified to achieve a more resistant top 30 um of silica has formed after engine testing, which layer

engine test are presented in Figs. 7 and 8, respectively. A three-layer EBC that was applied to both liners consisted of a BSAS top layer, a mullite or mullite+BSAS intermediate layer, and a silicon bottom layer. A layer of silica was formed during the engine test due to oxidation of the silicon layer. The EBC on the inner liner consisted of silicon (90–125 mm), silica (60–100 mm), mullite (75–100 mm), and BSAS (150–200 mm). On the outer liner, the EBC consisted of silicon (75–140 mm), silica (25–60 mm), mullite+BSAS (175– 225 mm), and BSAS (175–200 mm). The three-layer EBC system used on the outer liner performed better than on the inner liner. The addition of BSAS to mullite in the intermediate layer minimized/ reduced cracks and porosity in that layer, resulting in reduced oxidation of the silicon layer, and thus better protection of the liner. In addition, separation at the interface of the mullite intermediate layer and the silica layer was greatly reduced with the addition of BSAS. These results are consistent with Keiser rig testing results. A mullite+BSAS intermediate layer was used to coat the SiC/SiC liners used in first two Malden Mills and the sixth Texaco engine tests. Recession of the BSAS top layer, which was not observed in over 5000-h Keiser rig tests at ORNL, was observed on both liners exposed to engine environment (Fig. 9). The main difference between the Keiser rig and combustion environment is the gas velocity. Velocity plays an important role in the volatilization of silica.1,2 The Keiser rig operates at low velocities, less than 1 cm/s, versus gas velocities on the order of 85 m/s in the engine. The low velocity in the Keiser rig does not allow for complete volatilization, and recession results are reported based upon oxidation depth. Fortunately, even after partial BSAS recession, the EBC was still protective (Fig. 10). A uniform layer of approximately 30 mm of silica has formed after engine testing, which was consistent with 6500 h of Keiser Rig testing at 1200 C. In order to reduce the BSAS recession in future engine tests, either its thickness can be increased or the composition modified to achieve a more resistant top layer. Fig. 9. Recession of BSAS top layer EBC on the inner liner after 13,937-h field test. Fig. 10. EBC after recession of BSAS top layer on the outer liner after 13,937-h field test. The EBC is still protective even after some recession of the BSAS top layer. Fig. 11. Mullite phase separation of the intermediate layer into silica and alumina phases. Silica volatilization within the mullite layer leads to porosity. J. Kimmel et al. / Journal of the European Ceramic Society 22 (2002) 2769–2775 2773

J. Kimmel et al. Journal of the European Ceramic Society 22(2002)2769-2775 2775 3. Concluding remarks Acknowledgements The CfCc inner and outer liners used in the fifth This work was performed under DOE Contracts DE CSGT field test(13, 937 h) were destructively and non- ACo2-92CE40960 and DE-FC02-00CH11049. We are destructively evaluated. The EBCs spalled off at the aft- grateful to Stephen Waslo and Jill Jonkouski of the DOe end edges of both liners. The combustor design was Chicago Operations Office, and Patricia Hofman and modified to minimize/eliminate the spallation in the Debbie Haught of the DOE Office of Power Technologies sixth field test at Texaco. Several pinholes were for their technical and programmatic support. We observed on the outer liner, many of which correlated appreciate the contributions and guidance of Jerry Woods, with a repeatable pattern of surface asperities in the as- Don Leroux, Anthony Fahme, Zaher Mutasim, and Mark protected the liners effectively in the berities. The EBC HACL, Bill Ellingson, J.G. Sun and Chris Deemer ofA fabricated liner. The CFCC liner fabrication process is van Roode of Solar, Dennis Landini and Ali Fareed being modified to reduce surface a herethere was no spallation or localized oxidation. The (u ended) thick SiC seal coat layer was partly responsible References for the inner liner surviving almost 14,000 h despite a 1. Miriyala, N. Fahme, A and van Roode, M, Ceramic stationary major EBC spall in the earlier part(900 h) of the test as turbine program--combustor liner development summary The nDe techniques could detect flaws in the EBC ASME Paper 2001-GT-512, presented at the International Gas inner liner. the location of which correlated with the Turbine and Aeroengine Congress and Exposition, New Orleans major spall observed during the field test. Recession of LA. USA. June 2001 the Bsas top layer was observed, but even after partial 2. Eaton, H.E. et al. EBC protection of SiC/SiC composites in the as turbine combustion environment. ASME Paper 2000-GT BSAS recession the EBC was still protective. In order to 231, presented at the International Gas Turbine and Aeroengine reduce BSAS recession in future engine tests, either its Congress and Exposition, Munich, Germany, May 2000. ckness can be increased or the composition modified 3. Opila, E J and Hann, R. E, Paralinear oxidation of CVD SiC in to achieve a more resistant top layer. The three-layer 4. Pila. E.et al. sic recession due to s EBC system used on the outer liner was better than that combustion conditions. Part Il: thermodynamics and gaseous used on the inner liner. The addition of bsas to mullite diffusion model. J. Am. Ceram Soc. 1999, 827. 1826-1834 in the intermediate layer minimized /reduced cracks in 5. Jacobson. N. S. Corrosion of silicon-based ceramics in combus- that layer, resulting in better protection of the liner tion environments. J. Am. Ceram. Soc., 1993, 761. 3-28 However, the stability of mullite in the combustion of ceramics and ceramic matrix ites in simulated and actua tor environments environment appears to be an issue. The use of EBC ASME Paper 1999-GT-292, presented International gas coating increased the life of CFCC liners from approxi- Turbine and Aeroengine Congress and on, Indianapolis, mately 5000 to 14,000 h, roughly a 3-fold increase. It IN. USA. June 1999 appears that by avoiding/minimizing surface asperities 7. Elingson, WA. Sun, J.G. More, KL and Hines, R- Non- during the manufacture of the liners and making a few EBC compositional and processing changes, the desired bustor liners in advanced gas turbines. ASME Paper 2000-GT-68 presented at the International Gas Turbine and Aeroengine liner life of 30,000 h could potentially be achieved ongress and Exposition, Munich, Germany, May 2000

3. Concluding remarks The CFCC inner and outer liners used in the fifth CSGT field test (13,937 h) were destructively and nondestructively evaluated. The EBCs spalled off at the aftend edges of both liners. The combustor design was modified to minimize/eliminate the spallation in the sixth field test at Texaco. Several pinholes were observed on the outer liner, many of which correlated with a repeatable pattern of surface asperities in the asfabricated liner. The CFCC liner fabrication process is being modified to reduce surface asperities. The EBC protected the liners effectively in the areas where there was no spallation or localized oxidation. The (unintended) thick SiC seal coat layer was partly responsible for the inner liner surviving almost 14,000 h despite a major EBC spall in the earlier part (900 h) of the test. The NDE techniques could detect flaws in the EBC inner liner, the location of which correlated with the major spall observed during the field test. Recession of the BSAS top layer was observed, but even after partial BSAS recession the EBC was still protective. In order to reduce BSAS recession in future engine tests, either its thickness can be increased or the composition modified to achieve a more resistant top layer. The three-layer EBC system used on the outer liner was better than that used on the inner liner. The addition of BSAS to mullite in the intermediate layer minimized/reduced cracks in that layer, resulting in better protection of the liner. However, the stability of mullite in the combustion environment appears to be an issue. The use of EBC coating increased the life of CFCC liners from approximately 5000 to 14,000 h, roughly a 3-fold increase. It appears that by avoiding/minimizing surface asperities during the manufacture of the liners and making a few EBC compositional and processing changes, the desired liner life of 30,000 h could potentially be achieved. Acknowledgements This work was performed under DOE Contracts DEAC02-92CE40960 and DE-FC02-00CH11049. We are grateful to Stephen Waslo and Jill Jonkouski of the DOE Chicago Operations Office, and Patricia Hoffman and Debbie Haught of the DOE Office of Power Technologies for their technical and programmatic support. We appreciate the contributions and guidance of Jerry Woods, Don Leroux, Anthony Fahme, Zaher Mutasim, and Mark van Roode of Solar, Dennis Landini and Ali Fareed of HACI, Bill Ellingson, J.G. Sun and Chris Deemer of ANL. References 1. Miriyala, N., Fahme, A. and van Roode, M., Ceramic stationary gas turbine program—combustor liner development summary. ASME Paper 2001-GT-512, presented at the International Gas Turbine and Aeroengine Congress and Exposition, New Orleans, LA, USA, June 2001. 2. Eaton, H.E. et al., EBC protection of SiC/SiC composites in the gas turbine combustion environment. ASME Paper 2000-GT- 231, presented at the International Gas Turbine and Aeroengine Congress and Exposition, Munich, Germany, May 2000. 3. Opila, E. J. and Hann, R. E., Paralinear oxidation of CVD SiC in water vapor. J. Am. Ceram. Soc., 1997, 80[1], 197–205. 4. Opila, E. J. et al., SiC recession due to SiO2 scale volatility under combustion conditions. Part II: thermodynamics and gaseous diffusion model. J. Am. Ceram. Soc., 1999, 82[7], 1826–1834. 5. Jacobson, N. S., Corrosion of silicon-based ceramics in combustion environments. J. Am. Ceram. Soc., 1993, 76[1], 3–28. 6. More, K.L. et al., Exposure of ceramics and ceramic matrix composites in simulated and actual combustor environments. ASME Paper 1999-GT-292, presented at the International Gas Turbine and Aeroengine Congress and Exposition, Indianapolis, IN, USA, June 1999. 7. Ellingson, W.A., Sun, J.G., More, K.L., and Hines, R., Nondestructive characterization of ceramic composites used as combustor liners in advanced gas turbines. ASME Paper 2000-GT-68, presented at the International Gas Turbine and Aeroengine Congress and Exposition, Munich, Germany, May 2000. J. Kimmel et al. / Journal of the European Ceramic Society 22 (2002) 2769–2775 2775

《复合材料 Composites》课程教学资源（学习资料）第五章 陶瓷基复合材料_fiber107

《复合材料 Composites》课程教学资源（学习资料）第五章陶瓷基复合材料_fiber107