wwceramics. org/ACT Layered Interphases in SiC/SiC Composites extended to the matrix itself, oxygen being entrapped far S. Bertrand, O. Boisron, R. Pailler, J. Lamon, and R. Naslain, "(PyC-SiC) from the fiber surface and interphase, with unmatched and(BN-SiC. Nano-Scale Multilayered Interphases by Pressure Pulsed CV," Ko. Eng. Mater,164-165357-360(199 composite lifetimes. 5. The use of SiC/SiC in HT nuclear reactors is Ceramic Matrix Composites with Multilayered Interphase and Matrix for Im relatively new field of application. BN being excluded Rowed Oxidation Resistance, "Koy. Eng. Mater, 206-213 2189-2192 from nuclear consideration, the best interphase material W Yanget al. "Hi-Nicalon Fiber-Reinforced CVI-SIC Matrix Composites: seems again to be PyC. However, anisotropic PyC is not dimensionally stable under fast neutron irradiation, 12. W Yang.AKohyamaYKatoh,H.Araki,J.Yu,and TNoda,"Effectof which may alter FM bonding and composite mechanical 以TM↓ Fiber Reinforced Silicon Carlensom the Mechani山 lve this problem is to lower 3. F. Lamouroux, S Bertrand, R. Paillet, R. Naslain, and M. Cataldi, Oxida- the volume fraction of PyC in the interphase by either reducing its thickness(single-or multilayered interphases) rpos. Sai. Techn 73-1085(1999) to few nanometers or replacing pure carbon by C-SiC at 14. F. A. Christin, "A Global Approach to Fiber Architectures and Self-Seal Ceran. Technol the nanometer scale. Preliminary data suggest that the mechanical behavior of SiC/SiC with such interphases is 15. L L. Snead, R. H. Jones, A. Kohyama, and P. Fenici, "Status of Silicon not significantly degraded after neutron irradiation at 16. R H. Jone, ct al. "Promise and Ch. 507-3111057-1072 o2s94C 700-1000oC up to N 10 dpa. However, more studies, duding both representative mechanical testing and 17. Y. Katoh, et al,"Current Status and Critical Issues for Developme Composites for Fusion Applications, J. Nuck. Mater, 367-370 659-671 structure analysis of the interfacial zone(HR-TEM) should be pursued before considering that SiC/SiC fully 18. G. Newsome, L. L Snead, T. Hinoki, Y Katoh, and D. Peters, "Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites, all the requirements of this new and demanding Nucl Mate,37176-89(2007) applicatio Kohyama“ Mechanical Properties of Advanced SiC/SiC Composites after Neutron Irradiation, J. Nucl Mater.,367-370713-718(2007) Acknowledgments 20. Y. Katoh, T. Nozawa, L. L Snead, and T. Hinoki, "Effect of Neutron radiation on Tensile Properties of Unidirectional Silicon Carbide Com- The authors acknowledge the contribution of all 21. T. Nozawa, Y. Katoh, and L. L. Snead. " The Effects of Neutron Irradiation Shear Properties of Monolayered PyC and Multilayered PyC/SiC Inter- the researchers and engineers from both LCTS and its SPS and CEA Partners, who have been involved in re- 22.X Bourrat, B. Trouvat, G. Limousin, G. Vignoles, and F. Doux, " Pyroc bon Anisotropy as Measured by Electron Diffraction and Polarized Light, program on interphases for SiC/SiC. They are rbon,15[1]92-101(2000 ed to J. Forget and C. Duhau for their assistance 23.P nd R. Paillet. "Structure of Pyrocarbon Infiltrated by Pse-CⅥ," Carbon,33[91193-1204(1995) preparation of the present document. nd Toughened Traction Behavior, Mater. Res. Soc. Symp. Proc., 78 223- References 25.M ux and D. Cojean, Microtextures of Interfaces Related Mechanical Properties in Ceramic Fiber Reinforced Ceramic Matrix Com- Droillard, "Processing and Characterization of SiC-Matrix Composites of European Conference on Compesite Materials-5 eds,A Ph. D lo. 913, University of Nearly Stoichiometric SiC 2. C. Droillard and J. Lamon,"Fracture Toughness of 2D-Woven SiC/SiC Ceramic Fibers, . Mater. Sci, 36[10]2371-2382(2001 CVI-Composites with Multilayered Interphases, J. Am. Ceram. Soc., 79 [4] 27. J M. Jouin, ]. Cotteret, and F. Christin, "SiC/SiC Interphase: Case History, 849-858(1996 Designing Ceramic Interfaces l1. ed, S. D. Peteves. CEC, Luxembourg, 3. R. Naslain,"The Concept of Layered Interphases in SiC/SiC, "Ceram. 28. E. Lara-Curzio, M. K. Ferber and R. A. Lowden. "The Effect of Fiber Coar- Matrix Composites, Compes. Part A, 29A 1145-1155(1998). Matrix Composite, Ceram. Eng. Sci. Proc., 15 5]989-1000(1994). 5. R.A. Lowden, O. ]. Schwartz, and K. L More, " Improwed Fiber Coatings for 29. P. Dupel, J-L Bobet, R. Pailler, and J. Lamon, "Effect of Pyt icalon/ SiC Composites, "Cenam. Eng. Sci Proc, 14 [7/8]375-384(1993) Deposited by Pulsed-CVI on the Mechanical Prop ase in Ceramic Matrix Compo omposite Materials(in French), J.Phys. lll France, 5 937-961(1995) s,".Am.Ceam.So,742483-2488(1991) 30 inoki,E. Lara-Curzio, and LL Snead, "Mechanical Properties of 7. R.J. Kerans, R.S. Hay, T. A Parthasarathy, and M. K. Cinibulk, "Interface Design for Oxidation-Resistant Ceramic Composites,J.Am. Ceram. Soc., 8 hnol,44211-218(2003) 1]125992632(2002) 31. M. Y. He and J. W. Hutchinson, "Crack Deflection at an Interface Berween 8. S. Pasquier. J. Lamon, and R. Naslain, " Tensile Fatigue of 2D-SiC/SiC als, "Int.. Solids Struct, 25 [9] opposites with Multilayered (PyC-SiC) 32. I. Cook and I. E. Gordon, "A Mechanism for the in Oxidizing Atmosphere, Compos. Part A 29A 1157-1164(1998) Propagation in All-Brittle Systems, " Proc. R Soc., 28A 508-520extended to the matrix itself, oxygen being entrapped far from the fiber surface and interphase, with unmatched composite lifetimes. 5. The use of SiC/SiC in HT nuclear reactors is a relatively new field of application. BN being excluded from nuclear consideration, the best interphase material seems again to be PyC. However, anisotropic PyC is not dimensionally stable under fast neutron irradiation, which may alter FM bonding and composite mechanical properties. An approach to solve this problem is to lower the volume fraction of PyC in the interphase by either reducing its thickness (single- or multilayered interphases) to few nanometers or replacing pure carbon by C–SiC at the nanometer scale. Preliminary data suggest that the mechanical behavior of SiC/SiC with such interphases is not significantly degraded after neutron irradiation at 700–10001C up to 10 dpa. However, more studies, including both representative mechanical testing and structure analysis of the interfacial zone (HR-TEM) should be pursued before considering that SiC/SiC fully meet all the requirements of this new and demanding application. 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III France, 5 937–961 (1995). 30. T. Hinoki, E. Lara-Curzio, and L. L. Snead, ‘‘Mechanical Properties of High Purity SiC Fiber-Reinforced CVI-SiC Matrix Composites,’’ Fusion Sci. Technol., 44 211–218 (2003). 31. M. Y. He and J. W. Hutchinson, ‘‘Crack Deflection at an Interface Between Dissimilar Elastic Materials,’’ Int. J. Solids Struct., 25 [9] 1053–1067 (1989). 32. J. Cook and J. E. Gordon, ‘‘A Mechanism for the Control of Crack Propagation in All-Brittle Systems,’’ Proc. R. Soc., 28A 508–520 (1964). www.ceramics.org/ACT Layered Interphases in SiC/SiC Composites 273