G.H. Zhou et al. /Ceramics International 33(2007)1395-1398 liding stress should play an important role in the fiber pull-out [2] D. C. Phillips, R.A. Sambell, D. Bowen, The mechanical properties of lengths. Fig. 3a and b show microstructures at the fiber/matrix carbon fiber reinforced Pyrex glass, J. Mater. Sci. 7(1972)1454-1464. interface for these two samples. Without SiC, addition 3I R.A. Sambell, D.H. Bowen, D.C. Phillips, Carbon fiber composites with (Fig. 3a), the fiber/matrix interface is clear but a pore is 972)676681 entrapped. On the other hand, partial Sicp were sandwiched [4] D.C. Phillips, Interfacial bonding and the toughness of carbon fiber into the fiber/matrix interface in the SiCp added sample reinforced glass and glass-ceramics, J Mater. Sci. 9(1974)1847-1854 (Fig. 3b). The interfacial sliding stress caused by SiCp at the 5IT. Vasilis, T Erturk, R Ambati SCS-6 SiC hiber reinforced fused silica fiber/matrix interface enhanced the interfacial bonding strength (6) D.C. Jia, Y.Zhou, T.Q. Lei, Ambient andelevated temperature mechanical nd retarded the slippage. As a result, during flexural test, the roperties of hot-pressed fused silica matrix composite, J. Eur. Ceram. subtle effect of interface sliding stress among SiO2 matrix, Sicp Soc.23(2003)801-808 and carbon fibers resulted in the zigzag curve of the second [7] Q. Yu, Materials Technology, Series of Missiles and Spaceflight-Mate- elastic response and an increase of flexural strength perpend rials and Technology(Lower), Publishing House of Aerospace, Beijing. cular to the fiber direction 1993.pp.1-215 [8] J K. Guo, T.S. Yan, Microstructure and Properties of Ceramic Materials, Science Press, Beijing, 1984, Pp. 281-289 4. Conclusions [9] H.Q. Han, Microstructure and properties of several Sio2 matrix c Is Thesis, Harbin Institute of Technology. Harbin, 1995. pp (1) Uni-C/SiO and uni-C.SiO2+20 wt% SiCp composites [10] J.J. Yao, B.S. Li, X.X. Huang, J.K. Guo, Mechanical properties and its were prepared by slurry infiltration and hot-pressing. A ening mechanisms in SiO2-Si, N4 composite, J Inorg. Mater. 12(1) (1997)47-53 flexural strength of 667.3 MPa and fracture toughness of [11] G.W. Wen, G L Wu, T Q Lei, et al. Co-enhanced Sioz-BN ceramics for 20. 1 MPa m"parallel to the fiber direction for the uni-C+ high temperature dielectric applications, J. Eur. Ceram. Soc. 20(2000) Sio2 was attributed to the fiber pull-out. 1923-1928 (2)The flexural strength perpendicular to the fiber direction [12] G.T. Wu, Exploratory research on the applications of carbon fiber rein- increased from 18.0 to 54.3 MPa after the addition of sic forced silica on the thermal-protective structure of satellite and aero-ship pace Mater. Technol. 4(1991)72-78. The anisotropy of mechanical properties was strongly [131 Z.D. Guan, Z.T. Zhang J.S. Jiao, The Physical Properties of Inorganic modified for the uni-C/SiOz composite. Materials, Tsinghua University Publishing Company, 1992, p. 59. ()The dispersion of SiCp might enhance the interfacial sliding [14] H.Q. Han, QL Ge, T.Q. Lei, et al., The properties of fused silica increase of the fiber/matrix interfacial bonding strength and >/AG.Eales, Powder Metall.Technol.17(3)(1999)201-204 stress at the fiber/matrix interface which contributed to the e of fiber rein. forced ceramic matrix composites, high temperature/high perfo the flexural strength perpendicular to the fiber direction omposites, in: F.D. Lemkey, S.G. Fishman, et al. (Eds ) Mat. Res Soc symp.Poc,vol.120.1988,pp.213-24 16] H. Zhao, Z.Z. Jin, The analysis of residual stress and toughening mechan- References isms of particulate reinforced dual-phase ceramics, J Chin. Ceram. Soc 24(10)(1996)491-497 1] K.M. Prewo, J.J. Brennan, G.K. Layden, Fiber reinforced glasses and [17 M D. Thouless. O. Sbaizero, L.S. Sigl, A G. Evans, Effect of interface lass-ceramics for high performance applications, Ceram. Bull. 65(2) echanical properties on pullout in a SiC-fiber-reinforced LAS glass- (1986)305-313. ceramics, J. Am. Ceram Soc. 72(4)(1989)525-532sliding stress should play an important role in the fiber pull-out lengths. Fig. 3a and b show microstructures at the fiber/matrix interface for these two samples. Without SiCp addition (Fig. 3a), the fiber/matrix interface is clear but a pore is entrapped. On the other hand, partial SiCp were sandwiched into the fiber/matrix interface in the SiCp added sample (Fig. 3b). The interfacial sliding stress caused by SiCp at the fiber/matrix interface enhanced the interfacial bonding strength and retarded the slippage. As a result, during flexural test, the subtle effect of interface sliding stress among SiO2 matrix, SiCp and carbon fibers resulted in the zigzag curve of the second elastic response and an increase of flexural strength perpendi￾cular to the fiber direction. 4. Conclusions (1) Uni-Cf/SiO2 and uni-Cf/SiO2 + 20 wt.% SiCp composites were prepared by slurry infiltration and hot-pressing. A flexural strength of 667.3 MPa and fracture toughness of 20.1 MPa m1/2 parallel to the fiber direction for the uni-Cf/ SiO2 was attributed to the fiber pull-out. (2) The flexural strength perpendicular to the fiber direction increased from 18.0 to 54.3 MPa after the addition of SiCp. The anisotropy of mechanical properties was strongly modified for the uni-Cf/SiO2 composite. (3) The dispersion of SiCp might enhance the interfacial sliding stress at the fiber/matrix interface, which contributed to the increase of the fiber/matrix interfacial bonding strength and the flexural strength perpendicular to the fiber direction. References [1] K.M. Prewo, J.J. Brennan, G.K. Layden, Fiber reinforced glasses and glass-ceramics for high performance applications, Ceram. Bull. 65 (2) (1986) 305–313. [2] D.C. Phillips, R.A. Sambell, D. Bowen, The mechanical properties of carbon fiber reinforced Pyrex glass, J. Mater. Sci. 7 (1972) 1454–1464. [3] R.A. Sambell, D.H. Bowen, D.C. Phillips, Carbon fiber composites with ceramic and glass matrices. Part 2. Continuous fibers, J. Mater. Sci. 7 (1972) 676–681. [4] D.C. Phillips, Interfacial bonding and the toughness of carbon fiber reinforced glass and glass-ceramics, J. Mater. Sci. 9 (1974) 1847–1854. [5] T. Vasilos, T. Ertu¨rk, R. Ambati, SCS-6 SiC fiber reinforced fused silica composites, Ceram. Eng. Sci. Proc. 14 (9–10) (1993) 962–995. [6] D.C. Jia, Y. Zhou, T.Q. Lei, Ambient and elevated temperature mechanical properties of hot-pressed fused silica matrix composite, J. Eur. Ceram. Soc. 23 (2003) 801–808. [7] Q. Yu, Materials Technology, Series of Missiles and Spaceflight—Mate￾rials and Technology (Lower), Publishing House of Aerospace, Beijing, 1993, pp. 1–215. [8] J.K. Guo, T.S. Yan, Microstructure and Properties of Ceramic Materials, Science Press, Beijing, 1984, pp. 281–289. [9] H.Q. Han, Microstructure and properties of several SiO2 matrix compo￾sites, MS Thesis, Harbin Institute of Technology, Harbin, 1995, pp. 47–50. [10] J.J. Yao, B.S. Li, X.X. Huang, J.K. Guo, Mechanical properties and its toughening mechanisms in SiO2–Si3N4 composite, J. Inorg. Mater. 12 (1) (1997) 47–53. [11] G.W. Wen, G.L. Wu, T.Q. Lei, et al., Co-enhanced SiO2–BN ceramics for high temperature dielectric applications, J. Eur. Ceram. Soc. 20 (2000) 1923–1928. [12] G.T. Wu, Exploratory research on the applications of carbon fiber rein￾forced silica on the thermal-protective structure of satellite and aero-ship, Aerospace Mater. Technol. 4 (1991) 72–78. [13] Z.D. Guan, Z.T. Zhang, J.S. Jiao, The Physical Properties of Inorganic Materials, Tsinghua University Publishing Company, 1992, p. 59. [14] H.Q. Han, Q.L. Ge, T.Q. Lei, et al., The properties of fused silica composites, Powder Metall. Technol. 17 (3) (1999) 201–204. [15] A.G. Evans, D.B. Marshall, The mechanical performance of fiber rein￾forced ceramic matrix composites, high temperature/high performance composites, in: F.D. Lemkey, S.G. Fishman, et al. (Eds.), Mat. Res. Soc. Symp. Proc., vol. 120, 1988, pp. 213–246. [16] H. Zhao, Z.Z. Jin, The analysis of residual stress and toughening mechan￾isms of particulate reinforced dual-phase ceramics, J. Chin. Ceram. Soc. 24 (10) (1996) 491–497. [17] M.D. Thouless, O. Sbaizero, L.S. Sigl, A.G. Evans, Effect of interface mechanical properties on pullout in a SiC-fiber-reinforced LAS glass￾ceramics, J. Am. Ceram. Soc. 72 (4) (1989) 525–532. 1398 G.H. Zhou et al. / Ceramics International 33 (2007) 1395–1398