Journal of the American Ceramic Society-Sun et Vol. 80. No. 3 surface at lower temperatures; thus, oxygen can easily diffuse References along the crack via gas-phase J. J. Brennan, " Interfacial Characterization of Glass and Glass-Ceramic consumed by the oxidation of SiC fiber, because of the lower Matrix/Nicalon SiC Fiber Composites": pp. 549-60 in Materials Science reaction rate at the lower temperature, i.e., more oxygen is Research, Vol 20. Plenum, New York, 19 R. F. Cooper and K. Chyung, "Structure and Chemistry of Fibre-Matrix accumulated in the crack The condition be satisfied at 600C, and oxidation may possibly occur both in Microscopy Study,J Mater. ScL, 22, 3148-60(1987 SiC and BN. Also. no solid-state boron oxides formed in the J. Brennan, Fiber Reinforced Ceramic Composites; Ch. 8(Glass and Glass-Ceramic Matrix Composites"). Edited by K S. Mazdiyasni. Noyes, Par oxidized interfacial region in the samples that were tested at Ridge, NJ, 1990 600C, although the main reaction product of bn is the con- C. Cao. E. Bischoff. O. Sbaizero M. Ruhle. A. G. Evans. D. B. Marshall densed B,O, phase, according to thermodynamic calculations and J. J. Brennan, " Effect of Interfaces on the Properties of Fiber-Reinforced This could be caused by convection of gas-phase species. Diffu- ce,"BN Coating of Ceramic Fibers for Ceramic Fiber Com sion of BO(g)and B,O,(g) along the crack into the external U.S. Pat. No 4642271,Feb 10, 1987 environment could reduce the corresponder essures eristics in a Fiber-Reinforced in the crack and promote volatilization of solid BN. Overall, the Ga Narain omposeteand amG cere m bOron N tide interbase in( different oxidation behaviors at high and intermediate tem ratures and volatilization of solid BN at intermediate temper- SE. Y. Sun, S.R. Nutt, and J. J. Brennan, " Interfacial Microstructure and atures contributed to the different static-fatigue behaviors that Chemistry of SiC/BN Dual-Coated Nicalon-F ave been observed 里sm.sRa.,m Fiber-Reinforced Glass-Ceramic Composites, "J. Am. Ceram. Soc., 78 [5]1233- V. Conclusions Y. Sun, SR Nutt, and J J. Brennan, "High-Temperature Tensile Behavior The oxidation behavior of bn-coated Nicalon -fiber-reinforced of a Coated SiC Fiber Glass-Ceramic Composite, " J. Am. Ceram. Soc., 79 [6 1521-29(199 BMAS glass-ceramic composites at intermediate temperatures IR. T. Bhatt, Oxidation Effects on the Mechanical Properties of a Sic-Fiber- was studied. For this composite system, stress-induced degra- Reinforced Reaction-Bonded Si, N, Matrix Composite, "J. Am. Ceram. Soc., 75 dation in an oxidizing environment occurred more readily at 2]405-12(1992) 2K. P Plucknett, S. Sutherland, A M. Daniel, R L. Cain, G. West, D. M.R. intermediate temperatures than at high temperatures. No degra- in, and M. H. Lewis, ""Environmental Ageing Effects in a Silicon Carbide dation of the retained room-temperature strength was observed einforced Glass-Ceramic Matrix Composite, " J. Microsc., 177 [3 251 in composites that were static fatigued at 950%C under an appl ess of 350 MPa for 500 h, whereas an% decrease in the Degradation of Calcium K.P. Plucknett and M. H. Lewis, "Inhibition of Intermediate Temperature Pretreat retained strength was measured after static fatigue at 600oC under similar stress conditions. a porous silicon oxide glassy F. E. Heredia, J. C. McNulty, F. w. Zok, and A, G. Evans, " Oxidation layer was formed at the BN/fiber interface in the sample tested mbrittlement Probe for Ceramic-Matrix Composites, J.Amm. Ceram. Soc., 78 at 600C. because of surface oxidation of the fiber and volatil- S. R Nutt, and E. Y Sun, " Interfacial Studies of Coated Fiber zation of the bn coating layer. The present study suggested Reinforced Glass-Ceramic Matrix Composites, "Annual Rept. R93-970150-2 on that consideration of the kinetic effects, such as oxygen diffu- AFOSR Contract F49620-92-C-000 sion through the condensed phases and convection of gas-phase an, and G. K. Layden, "Fiber Reinforced Glasses species along the crack, is necessary to predict the intermediate- 65(21305-13, 322 gh Performance Applications, Am. Ce temperature oxidation behavior of BN-coated fiber in a ceramic T. Shimon, H. Chen, and K. Okamura, "Mechanism of Oxidation of matrix accurately Si-C-O Fibers, "J. Ceram. Soc. Jpn.(Nippon Seramikkusu Kyokai Gakuyut Ronbunsh),100,918-24(1992) Oxidation Kinetics Acknowledgmen The authors wish to thank Dr. D. N. Braski for CHaSICI3/H, under CVI Conditions, J. Mater. Sci., 27 uger analyses. Drs. P. F. Becher. E. Lara-Curzio and P. F. Tortorelli at ORNL heldon, E. Y. Sun, S. R Nutt, and J. J 当证 Oxidat nd Prof. B. w. Sheldon at Brown University(Providence, RI)are acknowledged BN-Coated SiC Fibers in Ceramic-Matrix Composites, "JAm Ceram Soc. 2]539-43(1996614 Journal of the American Ceramic Society— Sun et al. Vol. 80, No. 3 surface at lower temperatures; thus, oxygen can easily diffuse References 1 J. J. Brennan, “Interfacial Characterization of Glass and Glass-Ceramic along the crack via gas-phase transport. Second, less oxygen is Matrix/Nicalon SiC Fiber Composites”; pp. 549–60 in Materials Science consumed by the oxidation of SiC fiber, because of the lower Research, Vol. 20. Plenum, New York, 1986. reaction rate at the lower temperature; i.e., more oxygen is 2 R. F. Cooper and K. Chyung, “Structure and Chemistry of Fibre–Matrix accumulated in the crack. The condition p Interfaces in SiC Fibre-Reinforced Glass-Ceramic Composites: An Electron SiC O2 pBN O2 pO2 may Microscopy Study,” J. Mater. Sci., 22, 3148–60 (1987). be satisfied at 600C, and oxidation may possibly occur both in 3 J. J. Brennan, Fiber Reinforced Ceramic Composites; Ch. 8 (“Glass and SiC and BN. Also, no solid-state boron oxides formed in the Glass-Ceramic Matrix Composites”). Edited by K. S. Mazdiyasni. Noyes, Park oxidized interfacial region in the samples that were tested at Ridge, NJ, 1990. 4 H. C. Cao, E. Bischoff, O. Sbaizero, M. Ru¨ 600 hle, A. G. Evans, D. B. Marshall, C, although the main reaction product of BN is the con- and J. J. Brennan, “Effect of Interfaces on the Properties of Fiber-Reinforced densed B2O3 phase, according to thermodynamic calculations. Ceramics,” J. Am. Ceram. Soc., 73 [6] 1691–99 (1989). This could be caused by convection of gas-phase species. Diffu- 5 R. W. Rice, “BN Coating of Ceramic Fibers for Ceramic Fiber Composites,” sion of BO(g) and B U.S. Pat. No. 4 642 271, Feb. 10, 1987. 2O3(g) along the crack into the external 6 R. N. Singh, “Fiber–Matrix Interfacial Characteristics in a Fiber-Reinforced environment could reduce the corresponding partial pressures Glass-Ceramic Composite,” J. Am. Ceram. Soc., 72 [9] 1764–67 (1989). in the crack and promote volatilization of solid BN. Overall, the 7 R. Naslain, O. Dugne, and A. Guette, “Boron Nitride Interphase in Ceramic- different oxidation behaviors at high and intermediate tem- Matrix Composite,” J. Am. Ceram. Soc., 74 [10] 2482–88 (1991). 8 peratures and volatilization of solid BN at intermediate temper- E. Y. Sun, S. R. Nutt, and J. J. Brennan, “Interfacial Microstructure and Chemistry of SiC/BN Dual-Coated Nicalon-Fiber-Reinforced Glass-Ceramic atures contributed to the different static-fatigue behaviors that Matrix Composites,” J. Am. Ceram. Soc., 77 [5] 1329–39 (1994). have been observed. 9 E. Y. Sun, S. R. Nutt, and J. J. Brennan, “Flexural Creep of Coated SiC￾Fiber-Reinforced Glass-Ceramic Composites,” J. Am. Ceram. Soc., 78 [5] 1233– 39 (1995). V. Conclusions 10E. Y. Sun, S. R. Nutt, and J. J. Brennan, “High-Temperature Tensile Behavior of a Coated SiC Fiber Glass-Ceramic Composite,” J. Am. Ceram. Soc., 79 [6] The oxidation behavior of BN-coated Nicalon-fiber-reinforced 1521–29 (1996). 11 BMAS glass-ceramic composites at intermediate temperatures R. T. Bhatt, “Oxidation Effects on the Mechanical Properties of a SiC-Fiber￾Reinforced Reaction-Bonded Si was studied. For this composite system, stress-induced degra- 3N4 Matrix Composite,” J. Am. Ceram. Soc., 75 [2] 405–12 (1992). dation in an oxidizing environment occurred more readily at 12K. P. Plucknett, S. Sutherland, A. M. Daniel, R. L. Cain, G. West, D. M. R. intermediate temperatures than at high temperatures. No degra- Taplin, and M. H. Lewis, “Environmental Ageing Effects in a Silicon Carbide dation of the retained room-temperature strength was observed Fibre-Reinforced Glass-Ceramic Matrix Composite,” J. Microsc., 177 [3] 251– 63 (1995). in composites that were static fatigued at 950C under an applied 13K. P. Plucknett and M. H. Lewis, “Inhibition of Intermediate Temperature stress of 350 MPa for 500 h, whereas an
20% decrease in the Degradation of Calcium Aluminosilicate/Nicalon by High-Temperature Pretreat￾retained strength was measured after static fatigue at 600C ment,” J. Mater. Sci. Lett., 14, 1223–26 (1995). 14 under similar stress conditions. A porous silicon oxide glassy F. E. Heredia, J. C. McNulty, F. W. Zok, and A. G. Evans, “Oxidation Embrittlement Probe for Ceramic-Matrix Composites,” J. Am. Ceram. Soc., 78 layer was formed at the BN/fiber interface in the sample tested [8] 2097–100 (1995). at 600C, because of surface oxidation of the fiber and volatil- 15J. J. Brennan, S. R. Nutt, and E. Y. Sun, “Interfacial Studies of Coated Fiber ization of the BN coating layer. The present study suggested Reinforced Glass-Ceramic Matrix Composites,” Annual Rept. R93-970150-2 on AFOSR Contract F49620-92-C-0001, Nov. 30, 1993. that consideration of the kinetic effects, such as oxygen diffu- 16K. M. Prewo, J. J. Brennan, and G. K. Layden, “Fiber Reinforced Glasses sion through the condensed phases and convection of gas-phase and Glass-Ceramics for High Performance Applications,” Am. Ceram. Soc. Bull., species along the crack, is necessary to predict the intermediate- 65 [2] 305–13, 322 (1986). 17 temperature oxidation behavior of BN-coated fiber in a ceramic T. Shimoo, H. Chen, and K. Okamura, “Mechanism of Oxidation of matrix accurately. Si-C-O Fibers,” J. Ceram. Soc. Jpn. (Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi), 100, 918–24 (1992). 18L. Filipuzzi and R. Naslain, “Oxidation Kinetics of SiC Deposited from Acknowledgments: The authors wish to thank Dr. D. N. Braski for CH3SiCl3 /H2 under CVI Conditions,” J. Mater. Sci., 27, 3330–34 (1992). Auger analyses. Drs. P. F. Becher, E. Lara-Curzio, and P. F. Tortorelli at ORNL 19B. W. Sheldon, E. Y. Sun, S. R. Nutt, and J. J. Brennan, “Oxidation of and Prof. B. W. Sheldon at Brown University (Providence, RI) are acknowledged BN-Coated SiC Fibers in Ceramic-Matrix Composites,” J. Am. Ceram. Soc., 79 for helpful discussions. [2] 539–43 (1996).