Journal of the American Ceramic Sociery-Pere--Rigueiro et al. Vol. 82. No. 12 nterlayer at the BN/fiber interface of the as-received compos- Fabricated by Direct Metal Oxidation, "Ceram. Eng. Sci. Proc., 14 19-10 ite. No distinct oxidation interlayer was seen in the samples treated at 800oC, and such a layer developed only after I h at 12E. Y. Sun, S.R. Nutt, and JJ an,"High-Temperature Tensile Be- havior of a boron Nitride- Coated Silicon Carbide- Fiber Glass-Ceramic Com- 1200C. However, the layer that developed was significantly posite, J.Amt Ceram. Soc., 79[6] 1521-29(1996 thinner than that developed in the Al2O3-matrix composite at the same temperature(20 nm versus 100 nm). This difference ior at 20 and 1200.C of Nicalon-Silicon-Carbide- Fiber-Reinforced Alumina- suggests that the presence of a carbon-rich layer at the BN/fiber 14F E. Heredia, J C. McNulty, F. W. Zok, and A.G. Evans, "Oxidation nterface is deleterious to interface stability at high tempera- brittlement Probe for Ceramic-Matrix Composites, ". Am. Ceram. Soc., 78 ture, because carbon is rapidly burned out, facilitating the entry of oxygen into the sample ISE. Y. Sun, H.-T. Lin, and JJ. Brennan, "Interme Envi- ronmental Effects on Boron Nitride-Coated Silicon iber-Reinforced Acknowledgment: The authors are indebted to Dr. J. Y Pastor for his 16A. J. Eckel and R C. Bradt, "Strength Distributio rcing Fibers in help with the high-temperature mechanical test Infiltrated Silicon Carbide Matrix Compos- ite, " J. Am. Ceram Soc., 72 3J455-58(1989 racture Mirrors, "J. Am. Ceram Soc., 77[4J1075-78(1994 References JJ. Brennan and K. M. Prewo, "Silicon Carbide Fibre-Reinforced Glas acterization of Si-C(O) Fibe (CVI)Matrix Composites with a BN Inter- -K M. Prewo, JJ. Brennan, and G K. Layden, "Fiber-Reinforced Glasses Chemistry of SiC/BN Dual-Coated Nicalon-Fiber-Reinforced Glass-Ceramic 2R. Naslain, O. Dugne, A. Guette, J. Sevely, C R. Brosse, J.-P. Rocher, and amico, G. A. Bernhart, M. M. Dauchier, and J H. Mace, "SIC/SIC J. Cotteret, "Boron Nitride Interphase in Ceramic-Matrix Composites, "J.Am. Composites with Multilayered Interfaces,"J. Am. Ceram. Soc., 79 14] 849-58 with Carbon and Boron Nitride Interphases at Elevated Temperatures in Air, J. K M. Prewo, JJ. Brennan, B. Johnson, and S. Starrett, "Silicon Carbide H -T Lin and P. F. Becher "Effect of Fiber Coating on Lifetime of Nicalon Fibre-Reinforced Glass-Ceramic Composite Tensile Behaviour at Elevated Fiber-Silicon Carbide Composites, " Mater Sci Eng, A, A231, 143-50(1997). osed to High-Temperature Gaseous Environments, "J. Am. Ceram. Soc., 74 rials", pp. 111-22 in Fracture Mechanics of Ceramics, VoL 9. Edited by R C. J Clark, M. Jaffe, J. Rabe, and N. R. Langley, "Thermal Stability Char- radt, D P H Hasselman, D Munz, M. Sakai, and v. Y Schevchenko. Plenum acterization of SiC Ceramic Fibers: I, Mechanical Property and Chemical Struc- Timms, and J. 2L. C. Sawyer, R. T. Chen, F. Haimbach, P. J. Harget, E P. Prack, and M. [),si-6astng the Tensile Properties of Ceramic-Matrix Composites,"J.Met raphy and Structure, "Ceram. Eng. Sci. Proc., 719-10J914-30(1986) N. Frety and M. Boussuge, "Relationship between High-Temperature De E. Heredia, A. G. Evans, and C.A. Anderson, "Tensile and Shear Prop- ed SiC/AL,O, Composites Processed by op p. psucknens, s. sutherland. 4. M. Daniel. R.L. Cain, G. West. D. M. R der and R.T Chen,Strength, Structure, and Fracture Properties of Ceramic Fibers Produced Fibre-Reinforced Glass-Ceramic Matrix Composite, "J. Microsc., 177[3 251 from Polymeric Precursors: I, Base-Line Studies, "J. Am. Ceram. Soc., 70 [111 IoJ. LLorca, M. Elices, and J.A n,Toughness and Microstructural E. Erauzkin, M. Gutierrez, and J. LLorca, "Mechanical Properties of Ce- opposites for Aeroengine Applications"; pp. 761-68 in Ceramic and Metal Matrix Composites, CMMC 96. Edited by M. Fuentes, J M. Mar- oky, and C.R. ent of BN/ tinez-Esnaola, and A M. Daniel. Trans Tech Publications, Zurich, Switzerland SiC Duplex Fiber Coatings in Fiber-Reinforced Alumina Matrix Composites 1996interlayer at the BN/fiber interface of the as-received compos￾ite. No distinct oxidation interlayer was seen in the samples treated at 800°C, and such a layer developed only after 1 h at 1200°C. However, the layer that developed was significantly thinner than that developed in the Al2O3-matrix composite at the same temperature (20 nm versus 100 nm). This difference suggests that the presence of a carbon-rich layer at the BN/fiber interface is deleterious to interface stability at high tempera￾ture, because carbon is rapidly burned out, facilitating the entry of oxygen into the sample. Acknowledgment: The authors are indebted to Dr. J. Y. Pastor for his help with the high-temperature mechanical tests. References 1 J. J. Brennan and K. M. Prewo, “Silicon Carbide Fibre-Reinforced Glass￾Ceramic Matrix Composites Exhibiting High Strength and Toughness,” J. Mater. Sci., 17, 2371–83 (1982). 2 K. M. Prewo, J. J. Brennan, and G. K. Layden, “Fiber-Reinforced Glasses and Glass-Ceramics for High-Performance Applications,” Am. Ceram. Soc. Bull., 65 [2] 305–13 (1986). 3 P. J. Lamicq, G. A. Bernhart, M. M. Dauchier, and J. H. Mace, “SiC/SiC Composite Ceramics,” Am. Ceram. Soc. Bull., 65 [2] 336–38 (1986). 4 C. Droillard and J. Lamon, “Fracture Toughness of 2-D Woven SiC/SiC CVI Composites with Multilayered Interfaces,” J. Am. Ceram. Soc., 79 [4] 849–58 (1996). 5 K. M. Prewo, J. J. Brennan, B. Johnson, and S. Starrett, “Silicon Carbide Fibre-Reinforced Glass-Ceramic Composite Tensile Behaviour at Elevated Temperature, J. Mater. Sci., 24, 1371–79 (1989). 6 M. Gomina, J.-L. Chermant, and P. 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Jaffe, “Thermal Stability Characterization of SiC Ceramic Fibers: II, Fractog￾raphy and Structure,” Ceram. Eng. Sci. Proc., 7 [9–10] 914–30 (1986). 26F. E. Heredia, A. G. Evans, and C. A. Anderson, “Tensile and Shear Prop￾erties of Continuous Fiber-Reinforced SiC/Al2O3 Composites Processed by Melt Oxidation,” J. Am. Ceram. Soc., 78 [10] 2790–800 (1995). 27L. C. Sawyer, M. Jamieson, D. Brikowski, M. Ishaq Haider, and R. T. Chen, “Strength, Structure, and Fracture Properties of Ceramic Fibers Produced from Polymeric Precursors: I, Base-Line Studies,” J. Am. Ceram. Soc., 70 [11] 798–810 (1987). 28E. Erauzkin, M. Gutierrez, and J. LLorca, “Mechanical Properties of Ce￾ramic-Matrix Composites for Aeroengine Applications”; pp. 761–68 in Ceramic and Metal Matrix Composites, CMMC 96. Edited by M. Fuentes, J. M. Mar￾tínez-Esnaola, and A. M. Daniel. TransTech Publications, Zurich, Switzerland, 1996. h 3500 Journal of the American Ceramic Society—Pe´rez-Rigueiro et al. Vol. 82, No. 12