《复合材料 Composites》课程教学资源（学习资料）第五章陶瓷基复合材料_SiC-SiC-1.pdf_大学文库

Availableonlineatwww.sciencedirect.com Part A: applied science and manufacturing ELSEVIER Composites: Part A 37(2006)1396-1401 Corrosion of SiC/SiC composite in Na SO4 vapor environments from1000to1500°C Shoujun Wu, Aifei Cheng, Litong Zhang, Yongdong Xu, Xingang Luan, Hui mei National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, 547 Mailbox, Xian, Shaanxi 710072, People's Republic of china Received 21 December 2004: received in revised form 9 May 2005: accepted 9 July 2005 Abstract Corrosion of a three-dimensional SiC/SiC composite with a Cvd SiC coating was investigated in environments containing Na sO vapor, oxygen and water vapor at temperatures from 1000 to 1500C. The corrosion behavior was greatly related to temperature Below 1200C, the composite exhibited excellent resistance to corrosion, and then the residual flexural strength nearly kept the same value as the as-received strength. From 1200 to 1300C, the interaction of oxidation and corrosion led to a rapid weight gain. Above 1300C, weight loss due to volatilization and sublimation of si(oH)4 and Na,o. xSio on the surface increased continuously. At the same time, the gas release resulted in the formation of bubbles/corrosion pits and the maximum diameters of them increased with an increasing temperature Additionally, above 1200C, with an increasing temperature, the residual fexural strength of the composite decreased greatly 2005 Elsevier Ltd. All rights reserved Keywords: A. 3D SiC/SiC composite; B Corrosion; A Na2SO4 1. Introduction studied. However. the corrosion behaviors of SiC/SiC composite in environments contain- ites(SiC/SiC) are considered as the most promising ther- 1200C, have not been reported up to now. por above Silicon carbide fiber-reinforced silicon carbide compos- ing Na2SO4 vapor, oxygen and water vapor above mal structural materials due to their high toughness, The present investigation deals with the corrosion of a good resistance to thermal shock, good mechanical proper- 3D SiC/SiC composite with a CVD SiC coating in environ- ties at high temperature, especially improved iaw tolerance ments containing Na2 SO4 vapor, oxygen and water vapor and noncatastrophic mode of failure [1-3]. Besides oxida- at a range of temperature from 1000 to 1500C. Much of tion resistance, corrosion resistance is another important the analysis and discussion will then focus on the corrosion property of the composites that should be taken into con- mechanism of the composite assessed by the weight change sideration for long-time service, such as components for kinetics, residual flexural strength change and th e micro- high thrust/weight jet engines because the combustion gas structural analysis contains salts [4, 5]. The oxidation behavior of Sic-based composites in oxidizing environments containing water va- 2. Materials and experimental procedure por [6-8] and the corrosion behavior in Na2 SO4 [9]atmo- 2.1. Specimens preparation Corresponding author. Tel +86 29 8849 4616: fax: +86 29 8849 4620 Hi-Nicalon silicon carbide fiber from Japan Nippon E-inailaddress:shoujun_wu(@163.com(S.Wu) Carbon was employed. The fiber preformed was prepared 1359-835X/S- see front matter c 2005 Elsevier Ltd. All rights reserved

Corrosion of SiC/SiC composite in Na2SO4 vapor environments from 1000 to 1500 C Shoujun Wu *, Laifei Cheng, Litong Zhang, Yongdong Xu, Xingang Luan, Hui Mei National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, 547 Mailbox, Xi’an, Shaanxi 710072, People’s Republic of China Received 21 December 2004; received in revised form 9 May 2005; accepted 9 July 2005 Abstract Corrosion of a three-dimensional SiC/SiC composite with a CVD SiC coating was investigated in environments containing Na2SO4 vapor, oxygen and water vapor at temperatures from 1000 to 1500 C. The corrosion behavior was greatly related to temperature. Below 1200 C, the composite exhibited excellent resistance to corrosion, and then the residual flexural strength nearly kept the same value as the as-received strength. From 1200 to 1300 C, the interaction of oxidation and corrosion led to a rapid weight gain. Above 1300 C, weight loss due to volatilization and sublimation of Si(OH)4 and Na2O Æ xSiO2 on the surface increased continuously. At the same time, the gas release resulted in the formation of bubbles/corrosion pits and the maximum diameters of them increased with an increasing temperature. Additionally, above 1200 C, with an increasing temperature, the residual flexural strength of the composite decreased greatly. 2005 Elsevier Ltd. All rights reserved. Keywords: A. 3D SiC/SiC composite; B. Corrosion; A. Na2SO4 1. Introduction Silicon carbide fiber-reinforced silicon carbide composites (SiC/SiC) are considered as the most promising thermal structural materials due to their high toughness, good resistance to thermal shock, good mechanical properties at high temperature, especially improved flaw tolerance and noncatastrophic mode of failure [1–3]. Besides oxidation resistance, corrosion resistance is another important property of the composites that should be taken into consideration for long-time service, such as components for high thrust/weight jet engines because the combustion gas contains salts [4,5]. The oxidation behavior of SiC-based composites in oxidizing environments containing water vapor [6–8] and the corrosion behavior in Na2SO4 [9] atmosphere have been studied. However, the corrosion behaviors of SiC/SiC composite in environments containing Na2SO4 vapor, oxygen and water vapor above 1200 C, have not been reported up to now. The present investigation deals with the corrosion of a 3D SiC/SiC composite with a CVD SiC coating in environments containing Na2SO4 vapor, oxygen and water vapor at a range of temperature from 1000 to 1500 C. Much of the analysis and discussion will then focus on the corrosion mechanism of the composite assessed by the weight change kinetics, residual flexural strength change and the microstructural analysis. 2. Materials and experimental procedure 2.1. Specimens preparation Hi-Nicalone silicon carbide fiber from Japan Nippon Carbon was employed. The fiber preformed was prepared 1359-835X/$ - see front matter 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.compositesa.2005.07.010 * Corresponding author. Tel.: +86 29 8849 4616; fax: +86 29 8849 4620. E-mail address: shoujun_wu@163.com (S. Wu). www.elsevier.com/locate/compositesa Composites: Part A 37 (2006) 1396–1401

S. Wu et al /Composites: Part A 37(2006)1396-140 1397 using a four-step three-dimensional (4-step 3D) braiding 3. Results method, and was supplied by the Nanjing Institute of chemical vapor infiltration(LPCVI) process was em- degradatior change and residual flexural strength Glass Fiber, People's Republic of China. Low pressure 3. 1. Weight ployed to deposit pyrolytic carbon interphase and the sil- icon carbide matrix. The volume fraction of fibers was Fig. I shows weight change of the SiC/SiC composite about 40% and the braiding angle was about 200. The specimens with temperature after corrosion in environ interfacial layer of pyrocarbon(PyC) was deposited for ments containing Na2SO4 vapor, oxygen and water vapor I h at 870C and 5 kPa with C3H6. The deposited Pyc for different time Below 1200C, the weight gain increased interphase layer is about 0.2 um. Methyltrichlorosilane slowly as the temperature or experimental time increases (MTS, CH3 SiCl3) was used for the deposition of the From 1200 to 1300C, the weight gain strongly increased SiC matrix. MTS vapor was carried by bubbling hydro- with the temperature increasing. Additionally, the weight gen. The conditions for deposition of Sic matrix were as gain strongly increased with the experimental time increas- follows: the deposition temperature 1100C, pressure ing for the primordial 5 h, then decreased with the experi 5 kPa, time 20 h, the molar ratio of H, to methyltrichlo- mental time increasing. Above 1300C, the weight gain rosilane(MTS)10. Argon was employed as the dilute gas kept the same value for the primordial 2 h, and then it in to slow down the chemical reaction rate of deposition creased as the experimental time increases while decreased [10]. Specimens with dimension of 2.4 4.2 X 30.0 mm with the experimental time increases after 5 h. As experi were machined from the as-received composite and pol- mental time exceeded 2 h, the weight gain decreased as ished. The Sic coating was prepared on the substrates the temperature increased for 5 h to seal the open ends of the fibers after cutting ig. 2 shows the effect of temperature on the residual from the prepared composite flexural strength of SiC/SiC composite after corrosion in environments containing Na2SO4 vapor, oxygen and water 2. Corrosion tests vapor for 10 h. Below 1200C, the residual flexural strength nearly kept the same value as that of as-received The corrosion tests were conducted in simulated specimens(1193 MPa). Above 1200C, the residual flex- combustion environments containing Na SO4 vapor, oxy- ural strength strongly decreased with an increasing and water vapor at temperatures to 1500C for 10 h in a special device [6]. The Na2SO vapor was obtained by volatilization of Na 2SO4 in a corundum crucible at 900C after Na2SO4 powder was ntered at 900C for I h. The Na2SO4 vapor was carried into the reaction region by the mixed gas containing argon, oxygen and water vapor. The concen- tration of Na2SO4 was about 100 ppm, which was calcu lated by the measured weight loss of crucible with melted salt inside. The partial pressure of oxygen and water vapor were about 8000 and 14000 Pa, respectively. Three pecimens were used for each experimental condition 100011001200130014001500 The mass of the specimens were recorded after the specimens were corroded for 0, 2, 5, and 10 h at the Temperature(C) given temperature (1000, 1100, 1200, 1300, 1400, Fig. 1. Weight change of the SiC/SiC composite with temperature after 1500C),respectively. They were measured using an corrosion for different time electronic balance (METTLER TOLEDO AG204 sensitivity =0.I mg) 1200 2.3. Measurements of the composite specimens The flexural strength of the specimens before and after 10 h corrosion was measured by a three-point bending method. which was carried out on an Instron 1195 machine at room temperature. The span dimension was 20 mm and the loading rate was 0.5 mm/min. The fracture sections and the surfaces of the corrosive specimens were observed on a 100011001200130014001500 SEM(model JEOL JXA-840, SEM). The corrosion prod- ucts were analyzed by EDS (INCA 300)and XRD(Rigaku Fig. 2. Flexural strength change of the Sic/SiC composite with temper- DMAX-2400) ature after corrosion for 10 h

using a four-step three-dimensional (4-step 3D) braiding method, and was supplied by the Nanjing Institute of Glass Fiber, Peoples Republic of China. Low pressure chemical vapor infiltration (LPCVI) process was employed to deposit pyrolytic carbon interphase and the silicon carbide matrix. The volume fraction of fibers was about 40% and the braiding angle was about 20. The interfacial layer of pyrocarbon (PyC) was deposited for 1 h at 870 C and 5 kPa with C3H6. The deposited PyC interphase layer is about 0.2 lm. Methyltrichlorosilane (MTS, CH3SiCl3) was used for the deposition of the SiC matrix. MTS vapor was carried by bubbling hydrogen. The conditions for deposition of SiC matrix were as follows: the deposition temperature 1100 C, pressure 5 kPa, time 20 h, the molar ratio of H2 to methyltrichlorosilane (MTS) 10. Argon was employed as the dilute gas to slow down the chemical reaction rate of deposition [10]. Specimens with dimension of 2.4 · 4.2 · 30.0 mm were machined from the as-received composite and polished. The SiC coating was prepared on the substrates for 5 h to seal the open ends of the fibers after cutting from the prepared composite. 2.2. Corrosion tests The corrosion tests were conducted in simulated combustion environments containing Na2SO4 vapor, oxygen, and water vapor at temperatures ranging from 1000 to 1500 C for 10 h in a special device [6]. The Na2SO4 vapor was obtained by volatilization of Na2SO4 in a corundum crucible at 900 C after Na2SO4 powder was sintered at 900 C for 1 h. The Na2SO4 vapor was carried into the reaction region by the mixed gas containing argon, oxygen and water vapor. The concentration of Na2SO4 was about 100 ppm, which was calculated by the measured weight loss of crucible with melted salt inside. The partial pressure of oxygen and water vapor were about 8000 and 14000 Pa, respectively. Three specimens were used for each experimental condition. The mass of the specimens were recorded after the specimens were corroded for 0, 2, 5, and 10 h at the given temperature (1000, 1100, 1200, 1300, 1400, 1500 C), respectively. They were measured using an electronic balance (METTLER TOLEDO AG204, sensitivity = 0.1 mg). 2.3. Measurements of the composite specimens The flexural strength of the specimens before and after 10 h corrosion was measured by a three-point bending method, which was carried out on an Instron 1195 machine at room temperature. The span dimension was 20 mm and the loading rate was 0.5 mm/min. The fracture sections and the surfaces of the corrosive specimens were observed on a SEM (model JEOL JXA-840, SEM). The corrosion products were analyzed by EDS (INCA 300) and XRD (Rigaku D/MAX-2400). 3. Results 3.1. Weight change and residual flexural strength degradation Fig. 1 shows weight change of the SiC/SiC composite specimens with temperature after corrosion in environments containing Na2SO4 vapor, oxygen and water vapor for different time. Below 1200 C, the weight gain increased slowly as the temperature or experimental time increases. From 1200 to 1300 C, the weight gain strongly increased with the temperature increasing. Additionally, the weight gain strongly increased with the experimental time increasing for the primordial 5 h, then decreased with the experimental time increasing. Above 1300 C, the weight gain kept the same value for the primordial 2 h, and then it increased as the experimental time increases while decreased with the experimental time increases after 5 h. As experimental time exceeded 2 h, the weight gain decreased as the temperature increased. Fig. 2 shows the effect of temperature on the residual flexural strength of SiC/SiC composite after corrosion in environments containing Na2SO4 vapor, oxygen and water vapor for 10 h. Below 1200 C, the residual flexural strength nearly kept the same value as that of as-received specimens (1193 MPa). Above 1200 C, the residual flexural strength strongly decreased with an increasing temperature. –0.4 –0.2 0 0.2 0.4 0.6 0.8 1 1000 1100 1200 1300 1400 1500 Temperature(°C) Weight change(%) 2h 5h 10h Fig. 1. Weight change of the SiC/SiC composite with temperature after corrosion for different time. 500 600 700 800 900 1000 1100 1200 Residual flexural strength(MPa) 1000 1100 1200 1300 1400 1500 Temperature(°C) Fig. 2. Flexural strength change of the SiC/SiC composite with temperature after corrosion for 10 h. S. Wu et al. / Composites: Part A 37 (2006) 1396–1401 1397

S. Wu et aL. Composites: Part A 37(2006)1396-140 Na,OSIO B-Sic a a-Cristobalite AΔ△△ 1500°C 人A1400°C 1300°C 1200°C 1100°C 人A_10 Fig. 6. XRD patterns of the specimens' surface after corrosion at different temperature for 10 h. accelerated with an increasing temperature and the corro- composite was well protected from oxidation of reactions sion resistance of CVD Sic was poor (1H6) and nearly kept the same strength value as that in room temperature Above 1200C, though the accelerated 4. Discussion oxidation of Sic was strong. the volatilization and subli- mation of Si(oH)4 and Na20. xSiOz on the surfa In the present experimental condition, main reactions creased continuously, which led to weight loss. Along include the following with the experimental processing, the corrosion layer was Na2O(g)+SO: (1) more and more thick, which slow down the gas diffusion into the unreacted region while the weight loss on the sur SiC(s+3H2O(g= SiOz(s)+ 3H2(g)+ cog (2) face layer kept the constant. Moreover, bubbles/corrosion SiC(s)+ 302(g)= 2SiO2(s)+ 2CO(g) (3) pits, as shown in Fig 3(eHg) and 5 were formed in the cor SiOz(s)+ 2H2O()=Si(oH)4g (4) rosion layers. The diameter of them increased with increasing temperature. As a result, the weight gain Na2O(g)+x SiOz(s)= Na2O (5) reached the maximum value at 1300C, while it kept the SiC(s)+3SO3(g)=3SO2(g)+ Sic O C(s)+HO(g)=CO(g)+ hz(g) experimental time increased and decreased with the expe imental time increasing after 5h. Moreover, above C(s)+Orig)=Co (8) 1300C, the H2O, SO3 and O2 gas might diffuse into the composite and reacted with the pyrolytic carbon interlayer O3(g)+C(s)=SO2(g+ COc (9) according to reaction(7)9), though the diffusion was Below 1200C, according to reaction(2)4), accelerated slow. Furthermore, the strength of Hi-Nicalon fibers exhib oxidation of CVD Sic by water resulted in a thin layer ited degradation as temperature increased above 1200C protective SiO2 formed on the coating surface, which led [19-21]. Consequently, the residual flexural strength of to weight gain of the specimen [11-13]. Moreover, a low the composite strongly decreased as temperature increased. melting point Na20. xSio2 [14] was formed by reaction (5), as the surface EDS of specimens after corrosion for 5. Conclusions 10 h at 1100 and 1200C showed in Fig. 4. As a result, the defects in the coating and oxidation film would be The corrosion behavior of the 3D SiC/Sic composite sealed as shown in Fig 3(b)d). This behavior occurred was investigated in environments containing Na2 SO4 until all the available sodium was used up. At or near the vapor, oxygen and water vapor at temperatures from melt/gas interface, SiO2 could reform [15]. Under the coop- 1000 to 1500C. The corrosion behavior of the composite eration of them, the composite exhibited a slow slight was greatly related to temperature. Below 1200C, the ra- weight gain and the corrosion behaviors were similar to pid passive oxidation of CVD Sic coating by oxygen and oxidation in air, which differed from those showed by water vapor led to formation of a protective silica film Smialek et al. and Federer [15-18]. In this case, the and a slight weight gain, and then the residual flexural

accelerated with an increasing temperature and the corrosion resistance of CVD SiC was poor. 4. Discussion In the present experimental condition, main reactions include the following: Na2SO4ðlÞ ¼ Na2OðgÞ þ SO3ðgÞ ð1Þ SiCðsÞ þ 3H2OðgÞ ¼ SiO2ðsÞ þ 3H2ðgÞ þ COðgÞ ð2Þ 2SiCðsÞ þ 3O2ðgÞ ¼ 2SiO2ðsÞ þ 2COðgÞ ð3Þ SiO2ðsÞ þ 2H2OðgÞ ¼ SiðOHÞ4ðgÞ ð4Þ Na2OðgÞ þ xSiO2ðsÞ ¼ Na2O xSiO2ðlÞ ð5Þ SiCðsÞ þ 3SO3ðgÞ ¼ 3SO2ðgÞ þ SiO2ðsÞ þ COðgÞ ð6Þ CðsÞ þ H2OðgÞ ¼ COðgÞ þ H2ðgÞ ð7Þ CðsÞ þ O2ðgÞ ¼ COðgÞ ð8Þ SO3ðgÞ þ CðsÞ ¼ SO2ðgÞ þ COðgÞ ð9Þ Below 1200 C, according to reaction (2)–(4), accelerated oxidation of CVD SiC by water resulted in a thin layer protective SiO2 formed on the coating surface, which led to weight gain of the specimen [11–13]. Moreover, a low melting point Na2O Æ xSiO2 [14] was formed by reaction (5), as the surface EDS of specimens after corrosion for 10 h at 1100 and 1200 C showed in Fig. 4. As a result, the defects in the coating and oxidation film would be sealed as shown in Fig. 3(b)–(d). This behavior occurred until all the available sodium was used up. At or near the melt/gas interface, SiO2 could reform [15]. Under the cooperation of them, the composite exhibited a slow slight weight gain and the corrosion behaviors were similar to oxidation in air, which differed from those showed by Smialek et al. and Federer [15–18]. In this case, the composite was well protected from oxidation of reactions (1)–(6) and nearly kept the same strength value as that in room temperature. Above 1200 C, though the accelerated oxidation of SiC was strong, the volatilization and sublimation of Si(OH)4 and Na2O Æ xSiO2 on the surface increased continuously, which led to weight loss. Along with the experimental processing, the corrosion layer was more and more thick, which slow down the gas diffusion into the unreacted region while the weight loss on the surface layer kept the constant. Moreover, bubbles/corrosion pits, as shown in Fig. 3(e)–(g) and 5 were formed in the corrosion layers. The maximum diameter of them increased with increasing temperature. As a result, the weight gain reached the maximum value at 1300 C, while it kept the same value for the primordial 2 h, then increased as the experimental time increased and decreased with the experimental time increasing after 5 h. Moreover, above 1300 C, the H2O, SO3 and O2 gas might diffuse into the composite and reacted with the pyrolytic carbon interlayer according to reaction (7)–(9), though the diffusion was slow. Furthermore, the strength of Hi-Nicalon fibers exhibited degradation as temperature increased above 1200 C [19–21]. Consequently, the residual flexural strength of the composite strongly decreased as temperature increased. 5. Conclusions The corrosion behavior of the 3D SiC/SiC composite was investigated in environments containing Na2SO4 vapor, oxygen and water vapor at temperatures from 1000 to 1500 C. The corrosion behavior of the composite was greatly related to temperature. Below 1200 C, the rapid passive oxidation of CVD SiC coating by oxygen and water vapor led to formation of a protective silica film and a slight weight gain, and then the residual flexural Fig. 6. XRD patterns of the specimens surface after corrosion at different temperature for 10 h. 1400 S. Wu et al. / Composites: Part A 37 (2006) 1396–1401

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):2079-85

strength 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 silica led to a decreasing of weight gain when experimental time was beyond 5 h and further oxidation of the composite 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 carbidebased materials in a high temperature combustion environment. Key Eng Mater 1996;113:153–64. [6] Cheng Laifei, Xu Yongdong, Zhang Litong, Luan Xingang. Corrosion 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 combustion 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 fiberreinforced 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

《复合材料 Composites》课程教学资源（学习资料）第五章 陶瓷基复合材料_SiC-SiC-1

《复合材料 Composites》课程教学资源（学习资料）第五章陶瓷基复合材料_SiC-SiC-1