J.M. Ehrman et aL/Ce tes Science and Technology 67(2007)1425-1438 37 condition used in this effort. In steam, prior creep signifi thermal, and environmental testing and performance of ceramic cantly reduced fatigue life of the CMC ts. ASTM STP 1392. American Society for Testing and Materials: 2000. P. 210-5. 4.3. Composite microstructure 9] Hermes EE, Kerans RJ. Degradation of non-oxide reinforcement oxide matrix composites. Mat Res Soc Symp Proc 1988: 125: 73-8 [10] Szweda A, Millard ML, Harrison MG. Fiber-reinforced ceramic- All fracture surfaces obtained in this study exhibit matrix composite member and method for making. US Patent No 5 regions of uncoordinated brushy failure as well as areas of nearly planar fracture. Balance of the two types of frac- a Sim SM, Kerans RJ. Slurry infiltration and 3-D woven composites ture topography within a fracture surface is influenced by [12] Moore EH, Mah T, Keller KA. 3D composite fabrication through test type. Extensive uncorrelated fiber fracture is prevalent matrix slurry pressur in fracture surfaces produced in cyclic loading, while planar 1994: 15(4): 1 13-20 fracture dominates those obtained in creep In air and in [3]Lange FF, Tu wc, Evans AG. Processing of damage-tolerant, steam, the fracture surface appearance can be correlated with time to failure. Predominantly planar fracture surface (4)Mouchon E, Colomban P Oxide ceramic matrix/oxide fiber woven corresponds to a short life, while fibrous fracture is indica fabric composites exhibiting dissipative fracture behavior. Compos- tive of longer life ites I99526:17582 [15] Morgan PED, Marshall DB. Ceramic composites of monazite and 4.4. Energy dispersive X-ray spectroscopy(EDS) alumina. J Am Ceram Soc 1995: 78(6): 1553-63 [6Tu wc, Lange FF. Evans AG. Concept for a damage-tolerant ceramic composite with strong interfaces. J Am Ceram Soc Qualitative EDS analysis showed evidence of Si species 1996;92):417-2 migration from the mullite phase of the fiber to the alumina [17]Kerans RJ, Hay RS, Pagano NJ, Parthasarathy TA. The role of the matrix of the composite subjected to prior testing at fiber-matrix interface in ceramic composites. Am Ceram Soc Bul 1200C in steam. Depletion of the mullite phase in the 1989:68(2):42942. fiber may be the mechanism behind the degraded creep per- [18] Evans AG, Zok Fw. Review: the physics and mechanics of fiber- reinforced brittle matrix composites. J Mater Sci 1994; 29: 3857-96 formance of the composite in steam. Alternatively, poor [19]Kerans RJ, Parthasarathy TA. Crack deflection in ceramic compos- creep resistance in steam may be due to a stress-corrosion ites and fiber coating design criteria. Composites A 1999: 30 mechanism. In this case, crack growth in the fiber is caused 521-4. by a chemical interaction of water molecules with mechan- [20] Kerans R, Hay R, Parthasarathy T, Cinibulk M Interface design for cally strained Si-o bonds at the crack tip with the rate of oxidation-resistant ceramic composites. J Am Ceram Soc hemical reaction increasing exponentially with applied [21] Levi C, Yang J, Dalgleish B, Zok F, Evans AG. Processing and stress. Further experiments are necessary to determine erformance of an all-oxide ceramic composite. J Am Ceram Soc whether the observed behavior is due to the mullite loss from the fiber or to a stress-corrosion mechanism 22]Hegedus AG. Ceramic bodies of controlled pore laking same. US Patent No. 50177522, May 21: 1991 223]Zawada LP, Lee Ss. Evaluation of the fatigue performance of five References CMCs for aerospace applications. In: Proceedings of the sixth international fatigue congress: 1996. p. 1669-74 [U ]Zawada LP, Staehler J, Steel S Consequence of intermittent exposure [24] Lu TJ Crack branching in all-oxide composites. J Am Ceram to moisture and salt fog on the high-temperature fatigue durability of Soel996:791):266-74 eral ceramic-matrix composites. J Am Ceram Soc [25] Zok FW, Levi CG. Me 2003:86(8:1282-91. composites. Adv Eng Mater 2001; 3(1-2): 15-23 [2]Schmidt S, Beyer S, Knabe H, Immich H, Meistring R, Gessler A. [26]Zawada LP, Hay RS, Lee ss, Staehler J. Characterization and high- Advanced ceramic matrix composite materials for current and future mperature mechanical behavior of an oxide/oxide composite. J Am pplications. Acta Astron 2004: 55: 409-20 Ceram Soc2003:86(6:98l-90 [3] Parlier M, Ritti MH. State of the art and perspectives for oxide/oxide [27] Ruggles-Wrenn MB. Mall S, Eber CA, Harlan LB. Effects of steam composites. Aerospace Sci Technol 2003: 7: 211-21 environment on high-temperature mechanical behavior of Nex- [4]Prewo KM, Batt JA. The oxidative stability of carbon fibre reinforced tel720/Alumina (N720/A)continuous fiber ceramic composite glass-matrix composites J Mater Sci 1988: 23: 523-7 Composites Part A 2006 37(11): 2029-40 [5] Mah T, Hecht NL, McCullum DE, Hoenigman JR, Kim HM, Katz [28] Jurf RA, Butner SC. Advances in oxide-oxide CMC In: Proceedings AP, et al. Thermal stability of Sic fibres(Nicalon). J Mater Sci of the 44th ASME gas turbine and aeroengine congress and 984:19:1191-201 Indiana: 199 [6] More KL, Tortorelli PF, Ferber MK, Keiser JR. Observations of [29] Zawada LP, Lee Ss. The effect of hold times on the fatigue behavi ccelerated silicon carbide recession by oxidation at high water-vapor of an oxide/oxide ceramic matrix composite. In: Jenkins et al., ssures. J Am Ceram Soc 2000: 83(1): 211-3 editors. Thermal and mechanical test methods and behavior of [7 More KL, Tortorelli PF, Ferber MK, Walker LR, Keiser JR, ontinuousfiber ceramic composites. ASTM STP 1309. American Brentnall WD, et al. Exposure of ceramic and ceramic-matrix Society for Testing and Materials; 1997. p. 69-101 composites in simulated and actual combustor environments. In: B0] COI Ceramics. Unpublished data of international gas turbine and aerospace congress: [31]Hill RJ. The challenge of IPHTET. In: Bill editor. Eleventh AIAA: 1993 [8] Ferber MK, Lin HT, Keiser JR Oxidation behavior of non-oxide [32] Carelli EAV, Fujita H, Yang JY, Zok FW. Efects of thermal aging ramics in a high-pressure, hi ature steam environment. In. n the mechanical properties of a porous-matrix ceramic composite J Jenkins MG. Lara- Curzio editors. Mechanical Am Ceram soc2002;85(3):595602condition used in this effort. In steam, prior creep signifi- cantly reduced fatigue life of the CMC. 4.3. Composite microstructure All fracture surfaces obtained in this study exhibit regions of uncoordinated brushy failure as well as areas of nearly planar fracture. Balance of the two types of frac￾ture topography within a fracture surface is influenced by test type. Extensive uncorrelated fiber fracture is prevalent in fracture surfaces produced in cyclic loading, while planar fracture dominates those obtained in creep. In air and in steam, the fracture surface appearance can be correlated with time to failure. Predominantly planar fracture surface corresponds to a short life, while fibrous fracture is indica￾tive of longer life. 4.4. Energy dispersive X-ray spectroscopy (EDS) Qualitative EDS analysis showed evidence of Si species migration from the mullite phase of the fiber to the alumina matrix of the composite subjected to prior testing at 1200 C in steam. Depletion of the mullite phase in the fiber may be the mechanism behind the degraded creep per￾formance of the composite in steam. Alternatively, poor creep resistance in steam may be due to a stress-corrosion mechanism. In this case, crack growth in the fiber is caused by a chemical interaction of water molecules with mechan￾ically strained Si–O bonds at the crack tip with the rate of chemical reaction increasing exponentially with applied stress. Further experiments are necessary to determine whether the observed behavior is due to the mullite loss from the fiber or to a stress-corrosion mechanism. References [1] Zawada LP, Staehler J, Steel S. Consequence of intermittent exposure to moisture and salt fog on the high-temperature fatigue durability of several ceramic–matrix composites. J Am Ceram Soc 2003;86(8):1282–91. [2] Schmidt S, Beyer S, Knabe H, Immich H, Meistring R, Gessler A. Advanced ceramic matrix composite materials for current and future propulsion technology applications. Acta Astron 2004;55:409–20. [3] Parlier M, Ritti MH. State of the art and perspectives for oxide/oxide composites. Aerospace Sci Technol 2003;7:211–21. [4] Prewo KM, Batt JA. The oxidative stability of carbon fibre reinforced glass–matrix composites. J Mater Sci 1988;23:523–7. [5] Mah T, Hecht NL, McCullum DE, Hoenigman JR, Kim HM, Katz AP, et al. Thermal stability of SiC fibres (Nicalon). J Mater Sci 1984;19:1191–201. [6] More KL, Tortorelli PF, Ferber MK, Keiser JR. Observations of accelerated silicon carbide recession by oxidation at high water-vapor pressures. J Am Ceram Soc 2000;83(1):211–3. [7] More KL, Tortorelli PF, Ferber MK, Walker LR, Keiser JR, Brentnall WD, et al. Exposure of ceramic and ceramic–matrix composites in simulated and actual combustor environments. In: Proceedings of international gas turbine and aerospace congress; 1999. Paper No. 99-GT-292. [8] Ferber MK, Lin HT, Keiser JR. Oxidation behavior of non-oxide ceramics in a high-pressure, high-temperature steam environment. In: Jenkins MG, Lara-Curzio E, Gonczy ST, editors. Mechanical, thermal, and environmental testing and performance of ceramic composites and components. ASTM STP 1392. American Society for Testing and Materials; 2000. p. 210–5. [9] Hermes EE, Kerans RJ. Degradation of non-oxide reinforcement and oxide matrix composites. Mat Res Soc Symp Proc 1988;125:73–8. [10] Szweda A, Millard ML, Harrison MG. Fiber-reinforced ceramic– matrix composite member and method for making. US Patent No. 5 601 674; 1997. [11] Sim SM, Kerans RJ. Slurry infiltration and 3-D woven composites. Ceram Eng Sci Proc 1992;13(9–10):632–41. [12] Moore EH, Mah T, Keller KA. 3D composite fabrication through matrix slurry pressure infiltration. Ceram Eng Sci Proc 1994;15(4):113–20. [13] Lange FF, Tu WC, Evans AG. Processing of damage-tolerant, oxidation-resistant ceramic matrix composites by a precursor infil￾tration and pyrolysis method. Mater Sci Eng A 1995;195:145–50. [14] Mouchon E, Colomban P. Oxide ceramic matrix/oxide fiber woven fabric composites exhibiting dissipative fracture behavior. Compos￾ites 1995;26:175–82. [15] Morgan PED, Marshall DB. Ceramic composites of monazite and alumina. J Am Ceram Soc 1995;78(6):1553–63. [16] Tu WC, Lange FF, Evans AG. Concept for a damage-tolerant ceramic composite with strong interfaces. J Am Ceram Soc 1996;79(2):417–24. [17] Kerans RJ, Hay RS, Pagano NJ, Parthasarathy TA. The role of the fiber–matrix interface in ceramic composites. Am Ceram Soc Bull 1989;68(2):429–42. [18] Evans AG, Zok FW. Review: the physics and mechanics of fiber￾reinforced brittle matrix composites. J Mater Sci 1994;29:3857–96. [19] Kerans RJ, Parthasarathy TA. Crack deflection in ceramic compos￾ites and fiber coating design criteria. Composites A 1999;30: 521–4. [20] Kerans R, Hay R, Parthasarathy T, Cinibulk M. Interface design for oxidation-resistant ceramic composites. J Am Ceram Soc 2002;85(11):2599–632. [21] Levi C, Yang J, Dalgleish B, Zok F, Evans AG. Processing and performance of an all-oxide ceramic composite. J Am Ceram Soc 1998;81:2077–86. [22] Hegedus AG. Ceramic bodies of controlled porosity and process for making same. US Patent No. 5 0177 522, May 21; 1991. [23] Zawada LP, Lee SS. Evaluation of the fatigue performance of five CMCs for aerospace applications. In: Proceedings of the sixth international fatigue congress; 1996. p. 1669–74. [24] Lu TJ. Crack branching in all-oxide ceramic composites. J Am Ceram Soc 1996;79(1):266–74. [25] Zok FW, Levi CG. Mechanical properties of porous-matrix ceramic composites. Adv Eng Mater 2001;3(1–2):15–23. [26] Zawada LP, Hay RS, Lee SS, Staehler J. Characterization and high￾temperature mechanical behavior of an oxide/oxide composite. J Am Ceram Soc 2003;86(6):981–90. [27] Ruggles-Wrenn MB, Mall S, Eber CA, Harlan LB. Effects of steam environment on high-temperature mechanical behavior of Nex￾telTM720/Alumina (N720/A) continuous fiber ceramic composite. Composites Part A 2006;37(11):2029–40. [28] Jurf RA, Butner SC. Advances in oxide–oxide CMC. In: Proceedings of the 44th ASME gas turbine and aeroengine congress and exhibition, Indiana; 1999. [29] Zawada LP, Lee SS. The effect of hold times on the fatigue behavior of an oxide/oxide ceramic matrix composite. In: Jenkins et al., editors. Thermal and mechanical test methods and behavior of continuous-fiber ceramic composites. ASTM STP 1309. American Society for Testing and Materials; 1997. p. 69–101. [30] COI Ceramics. Unpublished data. [31] Hill RJ. The challenge of IPHTET. In: Billig FS, editor. Eleventh international symposium on air breathing engines. AIAA; 1993. [32] Carelli EAV, Fujita H, Yang JY, Zok FW. Effects of thermal aging on the mechanical properties of a porous-matrix ceramic composite. 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