《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_C-SiC-2-1.pdf_大学文库

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 209(2009)572-576 ELSEVIER journalhomepagewww.elsevier.com/locate/imatprotec Microstructure and tensile behavior of multiply needled C/Sic composite fabricated by chemical vapor infiltration Jingjiang Nie*, Yongdong Xu, Litong Zhang, Laifei Cheng, Jungiang Ma National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi'an Shaanxi 710072, China ARTICLE INFO A BSTRACT Article history: The microstructure and tensile behavior of a multiply needled C/SiC composite fabricated by chemical vapor infltration were investigated. Results showed that the tensile stress-strain Received in revised form curves exhibited a typical nonlinear behavior and can be divided into three regions: a very 16 January 2008 small initial linear region followed by a large nonlinear region and finally a quasi-linear gion Needling process caused a crimp around needling fibers and reduced the bearing fibers in plane Needling process induced damages were the main reasons for the failure of the composite. The fracture mainly occurred at the cross of needling fibers and uni- directional fibers, with the fibers showing multi-step fracture and extensive pullout. The Microstructure lulti-step fracture of clusters and nonlinear curves indicated a typical non-brittle failure Tensile behavior behavior of the multiply needled C/SiC composite due to the various damage patterns Multiply needled @2008 Elsevier B V. All rights reserved. C/SiC composite Chemical vapor infiltration Introduction properties and high fracture toughness(Camus et al., 1996; Wang and Laird, 1995; Wu et al., 2006). However, the 2D Carbon fiber reinforced silicon carbide ceramic matrix(C/Sic) composites have some fabrication problems and poor delam- omposites are widely used as structural materials in aero- ination resistance. 2. 5D and 3D braided composites have a nautic and space industries(.e, thermal protection systems superior delamination resistance(Ma et al., 2006; Boitier et al (Naslain, 2005; Christin, 2002), advanced propulsion(Schmidt 1997; Xu and Zhang, 1997)but have a high cost. To improve et al, 2004; Bouquet et al., 2003)and braking systems(Krenkel the delamination resistance and save cost, a unique kind and Berndt, 2005) due to their high damage tolerance with of multiply preform was developed by the means of the pseudo-ductility and strain-to-failure compared with mono- through-the-thickness needling technique. The multiply nee- lithic ceramics. Chemical vapor infiltration(cvn) is the most dled preforms have 3D architecture in real sense, which ar promising process for fabricating composites with advan- similar to that of Novoltex preforms reported in literatures tages of manipulating and modifying the microstructure of(Lacoste et al., 2002 )but differ significantly from the multiply the matrix, tailoring the fiber/matrix interface, and fabricat- stitched preforms reported in literatures(Mattheij et al., 2000 ing complex net or near-net shaped components at relatively Lomov et al., 2002). The multiply needled preforms consisted low temperatures(Chiang et al., 1989; Cao et al., 199 of unidirectional plies arranged in the desiredorientations and The mechanical properties and microstructure of 2D, 2.5D short-chopped fiber fabrics. The individual plies and fabrics and 3D C/Sic composites have been investigated extensively. were kept together by needling yarns. This structure led to 2D laminated composites have good in-plane mechanical an advantageous combination of high material properties and E-mail address ingiangnieosohucom 4. Niey 0924-0136/$-see front matter e 2008 Elsevier B V. All rights reserved. doi: 10.1016/j jmatprotec. 2008.02.035

journal of materials processing technology 209 (2009) 572–576 journal homepage: www.elsevier.com/locate/jmatprotec Microstructure and tensile behavior of multiply needled C/SiC composite fabricated by chemical vapor infiltration Jingjiang Nie ∗, Yongdong Xu, Litong Zhang, Laifei Cheng, Junqiang Ma National Key Laboratory of Thermostructure Composite Materials, Northwestern Polytechnical University, Xi’an Shaanxi 710072, China article info Article history: Received 3 February 2007 Received in revised form 16 January 2008 Accepted 16 February 2008 Keywords: Microstructure Tensile behavior Multiply needled C/SiC composite Chemical vapor infiltration abstract The microstructure and tensile behavior of a multiply needled C/SiC composite fabricated by chemical vapor infiltration were investigated. Results showed that the tensile stress–strain curves exhibited a typical nonlinear behavior and can be divided into three regions: a very small initial linear region followed by a large nonlinear region and finally a quasi-linear region. Needling process caused a crimp around needling fibers and reduced the bearing fibers in plane. Needling process induced damages were the main reasons for the failure of the composite. The fracture mainly occurred at the cross of needling fibers and unidirectional fibers, with the fibers showing multi-step fracture and extensive pullout. The multi-step fracture of clusters and nonlinear curves indicated a typical non-brittle failure behavior of the multiply needled C/SiC composite due to the various damage patterns. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Carbon fiber reinforced silicon carbide ceramic matrix (C/SiC) composites are widely used as structural materials in aeronautic and space industries (i.e., thermal protection systems (Naslain, 2005; Christin, 2002), advanced propulsion (Schmidt et al., 2004; Bouquet et al., 2003) and braking systems (Krenkel and Berndt, 2005)) due to their high damage tolerance with pseudo-ductility and strain-to-failure compared with monolithic ceramics. Chemical vapor infiltration (CVI) is the most promising process for fabricating composites with advantages of manipulating and modifying the microstructure of the matrix, tailoring the fiber/matrix interface, and fabricating complex net or near-net shaped components at relatively low temperatures (Chiang et al., 1989; Cao et al., 1990). The mechanical properties and microstructure of 2D, 2.5D and 3D C/SiC composites have been investigated extensively. 2D laminated composites have good in-plane mechanical ∗ Corresponding author. Fax: +86 29 8849 4620. E-mail address: jingjiangnie@sohu.com (J. Nie). properties and high fracture toughness (Camus et al., 1996; Wang and Laird, 1995; Wu et al., 2006). However, the 2D composites have some fabrication problems and poor delamination resistance. 2.5D and 3D braided composites have a superior delamination resistance (Ma et al., 2006; Boitier et al., 1997; Xu and Zhang, 1997) but have a high cost. To improve the delamination resistance and save cost, a unique kind of multiply preform was developed by the means of the through-the-thickness needling technique. The multiply needled preforms have 3D architecture in real sense, which are similar to that of Novoltex preforms reported in literatures (Lacoste et al., 2002) but differ significantly from the multiply stitched preforms reported in literatures (Mattheij et al., 2000; Lomov et al., 2002). The multiply needled preforms consisted of unidirectional plies arranged in the desired orientations and short-chopped fiber fabrics. The individual plies and fabrics were kept together by needling yarns. This structure led to an advantageous combination of high material properties and 0924-0136/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2008.02.035

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 209(2009)572-576 573 Carbon fibers transfered Layer n+1 when needling layer n+ Laver n-1 m,点 120 Fig 2- Schematic of tension specimens(dimensions in Fig. 1-Generation of 3D architecture preform with needling process. low cost processing. The needled preforms have good dimen- sional stability and good drapeability, making them suitable for fabricating composites with complicated shape(for exam- shaped parts In order to utilize these novel composites most effciently, thorough understanding of their mechanical properties is essential. It is well known that the fber architecture determines the composite microstructures and properties Therefore, in the present work, the microstructure and tensile behavior of the multiply needled C/Sic composite fabricated Strain/% Fig 3- Tensile stress-strain curves of the multiply needled C/Sic composite at room temperature 2. Experimental procedure 2.1. Preform preparation open porosity of the composite were 2.0-2.1g/cm and 14-17% respectively, determined by the Archimedes' method. The fibrous preforms fabricated by the through-the-thickness needling technique were supplied by Jiangsu Tianniao Insti- 2.3. Tension tests and microstructure observation tute of Carbon Fiber, China. The preforms were composed of unidirectional fibrous plies(also named as nonwoven web) Five specimens for tensile tests were prepared in the same fur- and short-chopped-fiber fabrics. In the present work, HTA nace runs. The shape and dimensions of the specimens are carbon fibers from Toho apan) were used for unidirectional shown in Fig. 2. To avoid local fracture at loading points, alu fibrous plies and T-700 12K carbon fibers from Toray (apan) minum end tabs were bonded to the specimens using an epoxy were used for short-chopped-flber fabrics. The ratio of unidi- resin adhesive. The tensile tests were conducted on an Instron rectional fibrous plies to short-chopped-fiber fabrics was 3: 1. 1196 test machine with a crosshead speed of 0.05 mm/min One unidirectional fibrous ply and one short-chopped-fiber Strains were recorded using an extensometer with a gauge fabric were named as one unit layer After each unit layer lami- length of 25 mm. Microstructure of the composite and the nated in desired orientations(0 /90)and sequences, needling fracture surfaces of the tested specimens were observed by process was carried out to keep adjacent units together with scanning electron microscopy(SEM, $4700 carbon fibers carried, as shown in Fig. 1. Hooks were designed on needle so that fibers stayed where they have been car- ried when needles left preform. As a result, each part of the 3. Results and discussion preform has received the same amount of transferred fibers 3.1. Tensile behavion through the thickness, and this provides the preform with good through-the-thickness homogeneity. The fiber volume The tensile stress-strain curves are shown in Fig.3.From fraction of the preform is about 30-32% Fig 3, the tensile stress-strain curves can be divided into three regions: a very small initial linear region with a low 2. Densification processing limitation stress followed by a large nonlinear region and finally a quasi-linear region. The large nonlinear region was To protect the carbon fibers from damage in the CVI process accompanied by a significant decrease in the modulus In fibers and the SiC matrix(Naslain, 1998, 2004), a pyrolytic gradually tended to be stable up to the failure of the compas and to weaken the interfacial bonding between the carbon the quasi-linear region, the modulus recovered very little ar carbon( Pyc) layer was deposited on the surface of carbon ite. As listed in Table 1, the average tensile strength and failure fibers as fiber/matrix interphase prior to the densification of strain for the composite are 158.9 MPa and 0.71%, respectively. Sic matrix CVI was employed to deposit PyC interphase and The average initiation modulus obtained by linear fitting of the Sic matrix. The conditions for CVi process were the same as stress-strain curves from o to 40 MPa is 75 GPa for the needled that described in reference(Xu et al., 1998). The density and C/Sic composite

journal of materials processing technology 209 (2009) 572–576 573 Fig. 1 – Generation of 3D architecture preform with needling process. low cost processing. The needled preforms have good dimensional stability and good drapeability, making them suitable for fabricating composites with complicated shape (for example, T-shaped and bell-shaped parts). In order to utilize these novel composites most efficiently, thorough understanding of their mechanical properties is essential. It is well known that the fiber architecture determines the composite microstructures and properties. Therefore, in the present work, the microstructure and tensile behavior of the multiply needled C/SiC composite fabricated by CVI were investigated. 2. Experimental procedure 2.1. Preform preparation The fibrous preforms fabricated by the through-the-thickness needling technique were supplied by Jiangsu Tianniao Institute of Carbon Fiber, China. The preforms were composed of unidirectional fibrous plies (also named as nonwoven web) and short-chopped-fiber fabrics. In the present work, HTA carbon fibers from Toho (Japan) were used for unidirectional fibrous plies and T-700 12 K carbon fibers from Toray (Japan) were used for short-chopped-fiber fabrics. The ratio of unidirectional fibrous plies to short-chopped-fiber fabrics was 3:1. One unidirectional fibrous ply and one short-chopped-fiber fabric were named as one unit layer. After each unit layer laminated in desired orientations (0◦/90◦) and sequences, needling process was carried out to keep adjacent units together with carbon fibers carried, as shown in Fig. 1. Hooks were designed on needle so that fibers stayed where they have been carried when needles left preform. As a result, each part of the preform has received the same amount of transferred fibers through the thickness, and this provides the preform with good through-the-thickness homogeneity. The fiber volume fraction of the preform is about 30–32%. 2.2. Densification processing To protect the carbon fibers from damage in the CVI process and to weaken the interfacial bonding between the carbon fibers and the SiC matrix (Naslain, 1998, 2004), a pyrolytic carbon (PyC) layer was deposited on the surface of carbon fibers as fiber/matrix interphase prior to the densification of SiC matrix. CVI was employed to deposit PyC interphase and SiC matrix. The conditions for CVI process were the same as that described in reference (Xu et al., 1998). The density and Fig. 2 – Schematic of tension specimens (dimensions in millimeter). Fig. 3 – Tensile stress–strain curves of the multiply needled C/SiC composite at room temperature. open porosity of the composite were 2.0–2.1 g/cm3 and 14–17%, respectively, determined by the Archimedes’ method. 2.3. Tension tests and microstructure observation Five specimens for tensile tests were prepared in the same furnace runs. The shape and dimensions of the specimens are shown in Fig. 2. To avoid local fracture at loading points, aluminum end tabs were bonded to the specimens using an epoxy resin adhesive. The tensile tests were conducted on an Instron 1196 test machine with a crosshead speed of 0.05mm/min. Strains were recorded using an extensometer with a gauge length of 25mm. Microstructure of the composite and the fracture surfaces of the tested specimens were observed by scanning electron microscopy (SEM, S4700). 3. Results and discussion 3.1. Tensile behavior The tensile stress–strain curves are shown in Fig. 3. From Fig. 3, the tensile stress–strain curves can be divided into three regions: a very small initial linear region with a low limitation stress followed by a large nonlinear region and finally a quasi-linear region. The large nonlinear region was accompanied by a significant decrease in the modulus. In the quasi-linear region, the modulus recovered very little and gradually tended to be stable up to the failure of the composite. As listed in Table 1, the average tensile strength and failure strain for the composite are 158.9 MPa and 0.71%, respectively. The average initiation modulus obtained by linear fitting of the stress–strain curves from 0 to 40 MPa is 75 GPa for the needled C/SiC composite

574 JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 209(2009)572-576 Table 1- Tensile properties of the multiply needled C/SiC composites Specimens UTS(MPa) Strain to UTS (% Initiation modulus(GPa) 15 1564 73 T4 75 1574 Avera 158.9 75.0 Fig 4- Microstructure of the multiply needled C/SiC composite (a) Top view and(b Side view The nonlinear tensile stress-strain behavior of the multiply 3.2. Microstructure observation needled C/Sic composite can be understood by the process induced damage and damage accumulation occurred in the Typically nonlinear tensile stress-strain curves indicated a composite under the increasing tensile stresses. The dam- typical non-brittle fracture behavior of the multiply nee- age accumulation included micro-cracks propagating, matrix dled C/Sic composite. To further understand the fracture cracking, interfacial debonding/sliding, and fibers breaking characteristics of the multiply needled C/Sic composite, the (Wang and Laird, 1995). Due to the mismatch of the ther- microstructures of the composite and the fracture surfaces mal expansion coeffcients between the carbon fibers and tested specimens were observed by SEM in this work. Fig 4 C matrix, there are some unavoidable microcracks existed shows the microstructure of the multiply needled C/ Sic com- within the Sic matrix. These microcracks propagated when posite before mechanical loading, and Fig. 5 shows the typical the tensile loading increased, accompanying with new micro- fracture surface of tested specimens. As shown in Fig. Sa, the racks initiated in the matrix. After the local stress exceeded fracture surface was very ragged, and the fracture of clus the load bearing capability of the Sic matrix, the microcracks ters mainly occurred at the crossover of needling fibers and joined together to form macrocracks, leading to the crack- unidirectional fibers Detailed observations revealed that the ing of the matrix. Then the tensile loading is mainly bone clusters fractured at various elevations(Fig 5b) by the carbon fibers From the mixture law for the compos The fracture characteristics mentioned above are closely ites, Ec=VAEf+VmEm, the modulus of the composites is mainly related to the microstructure of the composite and suitabl depended on ViEt, so the modulus of the composite decreased. thickness of the Pyc interphase. As shown in Fig. 4a, the Fig 5- Typical fracture morphologies of the multiply needled C/SiC composite (a) Fracture surface and (b)Pullout of carbon

574 journal of materials processing technology 209 (2009) 572–576 Table 1 – Tensile properties of the multiply needled C/SiC composites Specimens UTS (MPa) Strain to UTS (%) Initiation modulus (GPa) T1 161.5 0.66 76.7 T2 166.6 0.71 78.2 T3 156.4 0.73 75.6 T4 152.7 0.75 70.6 T5 157.4 0.72 73.7 Average 158.9 0.71 75.0 Deviation 5.3 0.03 2.9 Fig. 4 – Microstructure of the multiply needled C/SiC composite. (a) Top view and (b) Side view. The nonlinear tensile stress–strain behavior of the multiply needled C/SiC composite can be understood by the processinduced damage and damage accumulation occurred in the composite under the increasing tensile stresses. The damage accumulation included micro-cracks propagating, matrix cracking, interfacial debonding/sliding, and fibers breaking (Wang and Laird, 1995). Due to the mismatch of the thermal expansion coefficients between the carbon fibers and SiC matrix, there are some unavoidable microcracks existed within the SiC matrix. These microcracks propagated when the tensile loading increased, accompanying with new microcracks initiated in the matrix. After the local stress exceeded the load bearing capability of the SiC matrix, the microcracks joined together to form macrocracks, leading to the cracking of the matrix. Then the tensile loading is mainly borne by the carbon fibers. From the mixture law for the composites, Ec = VfEf + VmEm, the modulus of the composites is mainly depended on VfEf, so the modulus of the composite decreased. 3.2. Microstructure observation Typically nonlinear tensile stress–strain curves indicated a typical non-brittle fracture behavior of the multiply needled C/SiC composite. To further understand the fracture characteristics of the multiply needled C/SiC composite, the microstructures of the composite and the fracture surfaces of tested specimens were observed by SEM in this work. Fig. 4 shows the microstructure of the multiply needled C/SiC composite before mechanical loading, and Fig. 5 shows the typical fracture surface of tested specimens. As shown in Fig. 5a, the fracture surface was very ragged, and the fracture of clusters mainly occurred at the crossover of needling fibers and unidirectional fibers. Detailed observations revealed that the clusters fractured at various elevations (Fig. 5b). The fracture characteristics mentioned above are closely related to the microstructure of the composite and suitable thickness of the PyC interphase. As shown in Fig. 4a, the Fig. 5 – Typical fracture morphologies of the multiply needled C/SiC composite. (a) Fracture surface and (b) Pullout of carbon fibers

JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 209(2009)572-576 575 extensive pullout as shown in Fig 5b. This was according to the nonlinear tensile stress-strain curves as shown in Fig 3 SiC matrix Conclusions PyC interpet Tensile stress-strain curves exhibited a nonlinear behavior and can be divided into three regions: a very small ini tial linear region followed by a large nonlinear region and finally a quasi-linear region. The tested specimens mainly fractured at the crossover of needling fibers and unidirec tional fibers. And fracture surfaces were very ragged, with the fibers showing multi-step fracture and extensive pullout. The multi-step fracture of fibers and nonlinear stress-strain curves indicated a typical non-brittle behavior of the multi- Fig 6- Pyc interphase and interfacial debonding. ply needled C/Sic composite due to the multi-type damage patterms when specimens subjected to the increasing tensile stress Damage pattems included matrix cracks propagating, interfacial debonding/slidding, and fibers bridging and break- alignment of unidirectional carbon fibers was disturbed by ing Needling process caused a crimp around needling fibers needling fibers, resulting in a crimp around needling fibers. and reduced the fraction of bearing fibers in plane. All these As shown in Fig. 4b, the direction of needling fibers was needling-induced damages were the main reasons for the fail changed to through-thickness direction from in-plane direc- ure of the multiply needled C/SiC composite tion, so the uniformity of the ideal unidirectional plies was disturbed, lessening the amount of bearing-fibers in-plane at the needling locations. All damages mentioned above were Acknowledgements referred to "needling-induced damage". When specimens yere subjected to tension, the tensile loads were primarily The authors acknowledge the financial support of the Natu carried by fibers around the needling positions, so the stress ral Science Foundation of China( Contract no. 50672076, no concentrated within fiber clusters around the needling posi- 90405015)and the National Young Elitists Foundation(Con- tions Such stress concentrations can trigger localized damage tract no. 50425208) within fiber clusters. This can explain well why the fracture of the carbon fber clusters mainly occurred in needling areas. REFERENCES The composite properties were greatly influenced by the interfacial properties. The interphase of the tested specimens is shown in Fig. 6. The layered PyC interphase was introduced Boitier, G, Viens, J, Chermant, J L, 1997. Tensile creep results on into composites to weaken the bonding strength between Cr-SiC composite. Scripta Mater. 37(12), 1923-1929 carbon fibers and Sic matrix, so the interfacial debonding Bouquet, C, Fischer,R, Larrieu, J.M., Uhrig, G, Thebault,J, 2003 occurred when specimens subjected to tensile loads, as shown Composite technologies development status for scramjet in Fig. 6. Thus microcracks can be arrested and deflected by the pplications. In: 12th AIAA International Space Planes and PyC interphase, as shown in Fig. 7. As a result, the multiply ypersonic Systems and Technologies, Norfolk, America, December 15-19 needled C/Sic composite exhibited non-brittle fracture char- amus, G, Guillaumat, L, Baste, S, 1996. Development of acteristics, with the fibers showing multi-step fracture and damage in a 2D woven C/Sic composite under mechanical I. M 56,1363-1372 Cao. H C. Bischoff. E. Sbaizero. o. Ruhle. M.. Evans. A.G. Marshall, D B, Brennan, JJ., 1990. Effect of interfaces on the properties of fiber-reinforced ceramics. J Am Ceram Soc. 73 1691-1699 Chiang, Y.M., Haggerty, J.S., Messner, R.P., Demetry, C, 1989 Reaction-based processing methods for ceramic-matrix opposites. Am. Ceram Soc. Bull. 68(2) Christin, E, 2002. Design, fabriction, and application of nermostructural composites (rsC)like C/C, C/SiC, and Sic/Sic composites. Adv. Eng Mater. 4(12),903-912. Krenkel, W, Berndt, E, 2005. C/C-SiC composites for space applications and advanced friction systems. Mater. Sci. Eng. A 412,177-181 Lacoste. m. A. Joyez, P, 2002. Carbon/carbon xtendib Acta Astronaut. 50(6), 357-3 Lomov. s.v. B, Bischoff, T, Ghosh, S.B., Truong Chi, T. Fig 7- Deflection of microcracks and fracture of fibers. Verpoest, I, 2002. Carbon composites based on multiaxial

journal of materials processing technology 209 (2009) 572–576 575 Fig. 6 – PyC interphase and interfacial debonding. alignment of unidirectional carbon fibers was disturbed by needling fibers, resulting in a crimp around needling fibers. As shown in Fig. 4b, the direction of needling fibers was changed to through-thickness direction from in-plane direction, so the uniformity of the ideal unidirectional plies was disturbed, lessening the amount of bearing-fibers in-plane at the needling locations. All damages mentioned above were referred to “needling-induced damage”. When specimens were subjected to tension, the tensile loads were primarily carried by fibers around the needling positions, so the stress concentrated within fiber clusters around the needling positions. Such stress concentrations can trigger localized damage within fiber clusters. This can explain well why the fracture of the carbon fiber clusters mainly occurred in needling areas. The composite properties were greatly influenced by the interfacial properties. The interphase of the tested specimens is shown in Fig. 6. The layered PyC interphase was introduced into composites to weaken the bonding strength between carbon fibers and SiC matrix, so the interfacial debonding occurred when specimens subjected to tensile loads, as shown in Fig. 6. Thus microcracks can be arrested and deflected by the PyC interphase, as shown in Fig. 7. As a result, the multiply needled C/SiC composite exhibited non-brittle fracture characteristics, with the fibers showing multi-step fracture and Fig. 7 – Deflection of microcracks and fracture of fibers. extensive pullout as shown in Fig. 5b. This was according to the nonlinear tensile stress–strain curves as shown in Fig. 3. 4. Conclusions Tensile stress–strain curves exhibited a nonlinear behavior and can be divided into three regions: a very small initial linear region followed by a large nonlinear region and finally a quasi-linear region. The tested specimens mainly fractured at the crossover of needling fibers and unidirectional fibers. And fracture surfaces were very ragged, with the fibers showing multi-step fracture and extensive pullout. The multi-step fracture of fibers and nonlinear stress–strain curves indicated a typical non-brittle behavior of the multiply needled C/SiC composite due to the multi-type damage patterns when specimens subjected to the increasing tensile stress. Damage patterns included matrix cracks propagating, interfacial debonding/slidding, and fibers bridging and breaking. Needling process caused a crimp around needling fibers and reduced the fraction of bearing fibers in plane. All these needling-induced damages were the main reasons for the failure of the multiply needled C/SiC composite. Acknowledgements The authors acknowledge the financial support of the Natural Science Foundation of China (Contract no. 50672076, no. 90405015) and the National Young Elitists Foundation (Contract no. 50425208). references Boitier, G., Viens, J., Chermant, J.L., 1997. Tensile creep results on a Cf-SiC composite. Scripta Mater. 37 (12), 1923–1929. Bouquet, C., Fischer, R., Larrieu, J.M., Uhrig, G., Thebault, J., 2003. Composite technologies development status for scramjet applications. In: 12th AIAA International Space Planes and Hypersonic Systems and Technologies, Norfolk, America, December 15–19. Camus, G., Guillaumat, L., Baste, S., 1996. Development of damage in a 2D woven C/SiC composite under mechanical loading. I. Mechanical characterization. Compos. Sci. Technol. 56, 1363–1372. Cao, H.C., Bischoff, E., Sbaizero, O., Ruhle, M., Evans, A.G., ¨ Marshall, D.B., Brennan, J.J., 1990. Effect of interfaces on the properties of fiber-reinforced ceramics. J. Am. Ceram. Soc. 73 (6), 1691–1699. Chiang, Y.M., Haggerty, J.S., Messner, R.P., Demetry, C., 1989. Reaction-based processing methods for ceramic-matrix composites. Am. Ceram. Soc. Bull. 68 (2), 420– 428. Christin, F., 2002. Design, fabriction, and application of thermostructural composites (TSC) like C/C, C/SiC, and SiC/SiC composites. Adv. Eng. Mater. 4 (12), 903–912. Krenkel, W., Berndt, F., 2005. C/C–SiC composites for space applications and advanced friction systems. Mater. Sci. Eng. A 412, 177–181. Lacoste, M., Lacombe, A., Joyez, P., 2002. Carbon/carbon extendible nozzles. Acta Astronaut. 50 (6), 357–367. Lomov, S.V., Belov, E.B., Bischoff, T., Ghosh, S.B., Truong Chi, T., Verpoest, I., 2002. Carbon composites based on multiaxial

《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_C-SiC-2-1

《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_C-SiC-2-1