S. Wu et al / Composites: Part A 37(2006)1396-140 140 strength of the composite nearly kept the same value as [6] Cheng Laifei, Xu Yongdong, Zhang Litong, Luan Xingang. Corro. that of as-received. From 1200 to 1300oC. the accelerated sion of a 3D C/SiC composite in salt vapor environments. Carbon passive oxidation of CVd SiC coating by water resulted in 2002:40:877-82 weight gain which strongly increased as the temperature or [7] More KL, Tortorelli PF, Walker LR High-temperature stability of experimental time increased. However, volatilization of sil- Am Ceram Soc2003:868):1272-81. ica led to a decreasing of weight gain when experimental [8] Cheng Laifei, Xu Yongdong, Zhang Litong, Yin Xiaowei. Oxidation time was beyond 5 h and further oxidation of the cors,gp!Lowden RA, James RD High temperature corrosion of Nicalon/Sic te substrate Above 1300C, the cooperation of corrosic bustion environment. Compos: Part A 2000: 31: 1015-20 and gas release led to formation of a porous silicate layer composites. ORNL/TM-11893 p. 1-28 of the composite decreased with temperature increase [11] Tortorelli PF, More KL. Effects of high water-vapor on oxidation of silicon carbide at 1200C. J Am Ceram Soc 2003: 86(81): 1249-5 Acknowledgments [12 Opila EJ. Oxidation kinetics of chemically vapor-deposited silicon carbide in wet oxygen. J Am Ceram Soc 1994: 77(3): 730-6 The authors acknowledge the support of the Chinese [13] Opila EJ, Hann Jr rE Paralinear oxidation of CVD Sic in water National Foundation for Natural Sciences under Contract No.90405015 and the NSFC Distinguished Young Scholar [4 Levin EM, Robbins CR, Mcmurdie HE. Phase diagrams for under Contract No. 50425208. 2004. ceramists. Columbus, OH: The American Ceramic Society: 1964 [15] Jacobson NS, Smialek JL. Hot corrosion of sintered a-SiC at References 1000C. J Am Ceram Soc 1985: 68(81): 43 [16] Smialek JL, Jacobson NS. Mechanism of strength degradation for [Kimmel J, Miriyala N, Price J, More K, et al.. Evaluation of CFCC hot corrosion of -SIC. J Am Ceram Soc 1986: 69(101): 741-52. liners with EBC after field testing in a gas turbine. J Eur Ceram Soc Jacobson NS, Smialek JL. Corrosion pitting of by molten salts. J 2002;22(14-15):2769-75 Electrochem Soc Solid State Sci Technol 1986: 133(12): 2615-21 [2]Naslain R. Design, preparation and properties of non-oxide CMCs [8] Federer JI. Corrosion of SiC ceramics by Na2SO4.Adv Ceram Mater for application in engines and nuclear reactors: an overview. Compos 1988;3(1):56-6 Sci Technol 2004: 64: 155-70 [19]Ichikawa Hiroshi. Recent Advances in Nicalon Ceramic Fibres 3]Papakonstantinou CG, Balaguru P, Lyon RE Comparative study of Including Hi-Nicalon Type S Ann Chim Sci Mat 2000: 25: 523-8 high temperature composites Compos: Part B 2001: 32: 637-49. 20] Takeda Michio, Sakamoto Jun-ichi, Imai Yoshikazu, Ichikawa 4 Carruth M, Baxter D, Olivrira F, Coley K. Hot-corrosion of silicon Hiroshi. Thermal stability of the low-oxygen-content silicon carbide carbide in combustion gases at temperatures above the dew point of fiber, Hi-Nicalon. Compos Sci Technol 1999: 59(6): 8 alts. J Eur Ceram Soc 1998: 8: 2331-8. 221]Guo Shuqi, Kagawa Yutaka. Temperature depende 5 Graziani T, Baxter D, Nannetti CA Degradation of silicon carbide. strength for a woven boron-nitride- coated Hi-Nicalo fiber based materials in a high temperature combustion environment. Key einforced silicon-carbide-matrix composite. J Am Ceram Soc Eng mater I996;113:153-64 2001:84(9):2079-85strength of the composite nearly kept the same value as that of as-received. From 1200 to 1300 C, the accelerated passive oxidation of CVD SiC coating by water resulted in weight gain which strongly increased as the temperature or experimental time increased. However, volatilization of sil￾ica led to a decreasing of weight gain when experimental time was beyond 5 h and further oxidation of the compos￾ite substrate. Above 1300 C, the cooperation of corrosion and gas release led to formation of a porous silicate layer and CVD SiC exhibited poor resistance to corrosion of Na2SO4 vapor. Moreover, the residual flexural strength of the composite decreased with temperature increased. Acknowledgments The authors acknowledge the support of the Chinese National Foundation for Natural Sciences under Contract No. 90405015 and the NSFC Distinguished Young Scholar under Contract No. 50425208, 2004. References [1] Kimmel J, Miriyala N, Price J, More K, et al.. Evaluation of CFCC liners with EBC after field testing in a gas turbine. J Eur Ceram Soc 2002;22(14–15):2769–75. [2] Naslain R. Design, preparation and properties of non-oxide CMCs for application in engines and nuclear reactors: an overview. Compos Sci Technol 2004;64:155–70. [3] Papakonstantinou CG, Balaguru P, Lyon RE. Comparative study of high temperature composites. Compos: Part B 2001;32:637–49. [4] Carruth M, Baxter D, Olivrira F, Coley K. Hot-corrosion of silicon carbide in combustion gases at temperatures above the dew point of salts. J Eur Ceram Soc 1998;8:2331–8. [5] Graziani T, Baxter D, Nannetti CA. Degradation of silicon carbide￾based materials in a high temperature combustion environment. Key Eng Mater 1996;113:153–64. [6] Cheng Laifei, Xu Yongdong, Zhang Litong, Luan Xingang. Corro￾sion of a 3D C/SiC composite in salt vapor environments. Carbon 2002;40:877–82. [7] More KL, Tortorelli PF, Walker LR. High-temperature stability of SiC-based composites in high-water–vapor–pressure environments. J Am Ceram Soc 2003;86(8):1272–81. [8] Cheng Laifei, Xu Yongdong, Zhang Litong, Yin Xiaowei. Oxidation behavior of three-dimensional SiC/SiC composites in air and com￾bustion environment. Compos: Part A 2000;31:1015–20. [9] Lowden RA, James RD. High temperature corrosion of Nicalon/SiC composites. ORNL/TM-11893. p. 1–28. [10] Xu Yongdong, Cheng Laifei, Zhang Litong, et al.. High performance 3D textile Hi-Nicalon SiC/SiC composites by chemical vapor infiltration. Ceram Int 2001;27:565–70. [11] Tortorelli PF, More KL. Effects of high water–vapor on oxidation of silicon carbide at 1200 C. J Am Ceram Soc 2003;86(81):1249–55. [12] Opila EJ. Oxidation kinetics of chemically vapor-deposited silicon carbide in wet oxygen. J Am Ceram Soc 1994;77(3):730–6. [13] Opila EJ, Hann Jr RE. Paralinear oxidation of CVD SiC in water vapor. J Am Ceram Soc 1997;80(1):197–205. [14] Levin EM, Robbins CR, Mcmurdie HF. Phase diagrams for ceramists. Columbus, OH: The American Ceramic Society; 1964, p. 81. [15] Jacobson NS, Smialek JL. Hot corrosion of sintered a-SiC at 1000 C. J Am Ceram Soc 1985;68(81):432–9. [16] Smialek JL, Jacobson NS. Mechanism of strength degradation for hot corrosion of a-SiC. J Am Ceram Soc 1986;69(101):741–52. [17] Jacobson NS, Smialek JL. Corrosion pitting of by molten salts. J Electrochem Soc Solid State Sci Technol 1986;133(12):2615–21. [18] Federer JI. Corrosion of SiC ceramics by Na2SO4. Adv Ceram Mater 1988;3(1):56–61. [19] Ichikawa Hiroshi. Recent Advances in Nicalon Ceramic Fibres Including Hi-Nicalon Type S. Ann Chim Sci Mat 2000;25:523–8. [20] Takeda Michio, Sakamoto Jun-ichi, Imai Yoshikazu, Ichikawa Hiroshi. Thermal stability of the low-oxygen-content silicon carbide fiber, Hi-Nicalone. Compos Sci Technol 1999;59(6):813–9. [21] Guo Shuqi, Kagawa Yutaka. Temperature dependence of tensile strength for a woven boron-nitride-coated Hi-Nicalone SiC fiber￾reinforced silicon-carbide-matrix composite. J Am Ceram Soc 2001;84(9):2079–85. S. Wu et al. / Composites: Part A 37 (2006) 1396–1401 1401