October 2004 Zirconia-Silica-Carbon Coatings on Ceramic Fibers 1975 2.5 2.2 四5苏鸟 ZN-C 1.5 0.2? ZNS-C 15 Precursor Wt Loss% above t Fig 14. Strengths of ZrOx-SiO-carbon- and ZrO carbon-coated Nex. telM 720 after heat treatment for I h at 1000 C in air. Strengths are plotted 0.5 a function of coating precursor weight loss above 1000C(see Fig. 3). Results are mposed on results for monazite-coated Nextel 720 from an earlier study(Ref. 51). The weight loss value for ZNS-C is questionable because of weight gain that may be from oxidation of trace carbide. Long-Term Exposure at High Temperature, "J. Am. Ceram. Soc., 86(21 325-32 C Kaya, E. G. Butler, A Selcuk, A R. Boccaccini, and M. H. Lewis, "Mullite 40060080010001200 Properties, J. Eur. Ceram. Soc., 22, 2333-42(2002). E. D. Morgan and D. B. Marshall, "Ceramic Composites of Monazite and Temperature(C) eram.Soe.,7861553-63(1995) tel 720 fibers after coating and heat treatment in air and roated Nex. Oxide-Oxide Composites,"J. Eur. Ceram Soc, 20(51583-87(200Containing and Performance of an All-Oxide Ceramic Composite. "J Am. Cera Soc., 81 [8] 2077-86(1998) C. G. Levi and F. w. Zok. "Effects e on the Mechanical Properties of a Porous-Matrix. All-Oxide Ceramic Composi Hi-Nicalon s and Nextel720 fiber strengths are not "Performance of Four Ceramic-Matrix Com- significantly affected by coating as long as carbon remains in the posite Divergent Flap Inserts Following Ground Testing on an F110 Turbofan coating. Coated-fiber strengths degrade when carbon is removed by heat treatment in air at 21000C. Strength degradation of 上VcmH1123w面 of thermalA Hi-Nicalon s is so severe that thorough characterization of relationships between strength, temperature, and microstructures low-C. Tu. F. F. Lange. and A. G. Evans, "Concept for a Damage-Tolerant cannot be done Ceramic Composite with"" Interfaces, J. Am. Ceram. Soc., 79 [2]417-24 Degradation of Nextel 720 fibers is more severe when SiO, is present and when coating precursors contain a nitrate. A small Interface. Ceram. Eng. Sci. Proc. 16(41497-505 (1995). ant Fiber Coating for CMC containing coatings. bu with monazite-coated fibers, this1"E. BPakite, ". Mater. Res, 12 (5)1287-96(1997. ber Coating in SiC-Si, amount of fiber grain growth may be associated with Zro rain growth does not correlate with strength degradation. Degra R. S. Hay, and M. D. Petry, "Mixed Carbon-Aluminum Oxide dation may be caused by high-temperature stress corrosion from a Geochemisty of Oxides, 0onshandr stides and elated Ma en al. Edited by l. voight. surface-active decomposition product of the coating precursors T Wood, B Bunker, and B. casey. Materials Research Socicty. Pittsburgh, PA 1997 that contains nitrogen. This also is consistent with previous conclusions for monazite-coated fibers. This gas may be trapped and Oxide Coatings on Continuous Ceramic Fibers": Pp. 377-82 in Ceramic Matrix at higher local partial pressures by dense coatings, such as those aterials. M: 365. Edited by R. A. Lowden, M. K. Ferber that contain SiO,, and, consequently, degradation may be more J.R. Hellmann, and S G. DiPetro. Materials Research Society. Pittsburgh, PA, 1995 serious. It is possible that surface-active carbon in a coating may scavenge this gas and, consequently, decrease the fiber strength Porous Zio=SiO, and Monazite Coatings using Nextel ni 720 Fiber- Reinton d IeM. 3. 0Brien and B. W. Sheldon. "Porous Alumina Coating with Ta opposites. "J Am. Ceran. Soc., 82(1235 (1999) References J.B. Davis, AKristoffersson, E Carlstrom, and W.I.Clegg."Fabrication and tion in Ceramic Laminates with Porous Interlayers, "J. Am. Ceram Soc IR. J. Kerans, R. S. Hay, T. A. Parthasarathy, and M. K. Cinibulk, 8310]2369-74(2000 Design for Oxidation-Resistant Ceramic Composites, J. Am. Ceran. Soc., 85 [11] K.A. Keller. T Mah, T.A. Parthasarathy, EE Boakye, P. Mogilevsky, and M.K. Kanno, "Thermodynamic and Crystallographic Discussion of the Formation Cinibulk,"Effectiveness of Monazite Coatings in Oxide/Oxide Composites after and Dissociation of Zircon J. Mater. Sci. 24. 2415-20(1989).Hi-Nicalon STM and NextelTM 720 fiber strengths are not significantly affected by coating as long as carbon remains in the coating. Coated-fiber strengths degrade when carbon is removed by heat treatment in air at
1000°C. Strength degradation of Hi-Nicalon S is so severe that thorough characterization of relationships between strength, temperature, and microstructures cannot be done. Degradation of Nextel 720 fibers is more severe when SiO2 is present and when coating precursors contain a nitrate. A small amount of fiber grain growth may be associated with ZrO2- containing coatings, but, as with monazite-coated fibers,53 this grain growth does not correlate with strength degradation. Degra￾dation may be caused by high-temperature stress corrosion from a surface-active decomposition product of the coating precursors that contains nitrogen. This also is consistent with previous conclusions for monazite-coated fibers.51 This gas may be trapped at higher local partial pressures by dense coatings, such as those that contain SiO2, and, consequently, degradation may be more serious. It is possible that surface-active carbon in a coating may scavenge this gas and, consequently, decrease the fiber strength degradation. References 1 R. J. Kerans, R. S. Hay, T. A. Parthasarathy, and M. K. Cinibulk, “Interface Design for Oxidation-Resistant Ceramic Composites,” J. Am. Ceram. Soc., 85 [11] 2599–632 (2002). 2 K. A. Keller, T. Mah, T. A. Parthasarathy, E. E. Boakye, P. Mogilevsky, and M. K. Cinibulk, “Effectiveness of Monazite Coatings in Oxide/Oxide Composites after Long-Term Exposure at High Temperature,” J. Am. Ceram. Soc., 86 [2] 325–32 (2003). 3 C. Kaya, E. G. Butler, A. Selcuk, A. R. Boccaccini, and M. H. Lewis, “Mullite (NextelTM 720) Fibre-Reinforced Mullite-Matrix Composites Exhibiting Favourable Thermomechanical Properties,” J. Eur. Ceram. Soc., 22, 2333– 42 (2002). 4 P. E. D. Morgan and D. B. Marshall, “Ceramic Composites of Monazite and Alumina,” J. Am. Ceram. Soc., 78 [6] 1553– 63 (1995). 5 J. B. Davis, D. B. Marshall, and P. E. D. Morgan, “Monazite-Containing Oxide–Oxide Composites,” J. Eur. Ceram. Soc., 20 [5] 583– 87 (2000). 6 C. G. Levi, J. Y. Yang, B. J. Dalgleish, F. W. Zok, and A. G. Evans, “Processing and Performance of an All-Oxide Ceramic Composite,” J. Am. Ceram. Soc., 81 [8] 2077– 86 (1998). 7 M. A. Mattoni, J. Y. Yang, C. G. Levi, and F. W. Zok, “Effects of Matrix Porosity on the Mechanical Properties of a Porous-Matrix, All-Oxide Ceramic Composite,” J. Am. Ceram. Soc., 84 [11] 2594 – 602 (2001). 8 J. M. Staehler and L. P. Zawada, “Performance of Four Ceramic-Matrix Com￾posite Divergent Flap Inserts Following Ground Testing on an F110 Turbofan Engine,” J. Am. Ceram. Soc., 83 [7] 1727–38 (2000). 9 E.A. V. Carelli, H. Fujita, J. Y. Yang, and F. W. Zok, “Effects of Thermal Aging on the Mechanical Properties of a Porous-Matrix Composite,” J. Am. Ceram. Soc., 85 [3] 595– 602 (2002). 10W.-C. Tu, F. F. Lange, and A. G. Evans, “Concept for a Damage-Tolerant Ceramic Composite with ‘Strong’ Interfaces,” J. Am. Ceram. Soc., 79 [2] 417–24 (1996). 11L. U. J. T. Ogbuji, “A Porous, Oxidation-Resistant Fiber Coating for CMC Interface,” Ceram. Eng. Sci. Proc., 16 [4] 497–505 (1995). 12L. U. J. T. Ogbuji, “Evaluation of a Porous Fiber Coating in SiC–Si3N4 Minicomposite,” J. Mater. Res., 12 [5] 1287–96 (1997). 13E. Boakye, R. S. Hay, and M. D. Petry, “Mixed Carbon–Aluminum Oxide Coatings from Aqueous Sols and Solutions”; pp 363– 68 in Aqueous Chemistry and Geochemistry of Oxides, Oxyhydroxides, and Related Materials. Edited by J. Voight, T. Wood, B. Bunker, and B. Casey. Materials Research Society, Pittsburgh, PA, 1997. 14R. S. Hay, M. D. Petry, K. A. Keller, M. K. Cinibulk, and J. R. Welch, “Carbon and Oxide Coatings on Continuous Ceramic Fibers”; pp. 377– 82 in Ceramic Matrix Composites—Advanced High-Temperature Structural Materials, Materials Research Society Symposium Proceedings, Vol. 365. Edited by R. A. Lowden, M. K. Ferber, J. R. Hellmann, and S. G. DiPetro. Materials Research Society, Pittsburgh, PA, 1995. 15T. A. Parthasarathy, E. Boakye, K. A. Keller, and R. S. Hay, “Evaluation of Porous ZrO2–SiO2 and Monazite Coatings using NextelTM 720 Fiber-Reinforced Blackglas-Matrix Minicomposites,” J. Am. Ceram. Soc., 84 [7] 1526 –32 (2001). 16M. J. O’Brien and B. W. Sheldon, “Porous Alumina Coating with Tailored Fracture Resistance for Alumina Composites,” J. Am. Ceram. Soc., 82 [12] 3567–74 (1999). 17J. B. Davis, A. Kristoffersson, E. Carlstrom, and W. J. Clegg, “Fabrication and Crack Deflection in Ceramic Laminates with Porous Interlayers,” J. Am. Ceram. Soc., 83 [10] 2369 –74 (2000). 18B. F. Sorensen and A. Horsewell, “Crack Growth along Interfaces in Porous Ceramic Layers,” J. Am. Ceram. Soc., 84 [9] 2051–59 (2001). 19Y. Kanno, “Thermodynamic and Crystallographic Discussion of the Formation and Dissociation of Zircon,” J. Mater. Sci., 24, 2415–20 (1989). Fig. 13. Strengths of ZrO2–SiO2– carbon- and ZrO2– carbon-coated Nex￾telTM 720 fibers after coating and heat treatment in air and argon. Fig. 14. Strengths of ZrO2–SiO2– carbon- and ZrO2– carbon-coated Nex￾telTM 720 after heat treatment for 1 h at 1000°C in air. Strengths are plotted as a function of coating precursor weight loss above 1000°C (see Fig. 3). Results are superimposed on results for monazite-coated Nextel 720 from an earlier study (Ref. 51). The weight loss value for ZNS-C is questionable because of weight gain that may be from oxidation of trace carbide. October 2004 Zirconia–Silica–Carbon Coatings on Ceramic Fibers 1975