972 Commmunications of the American Ceramic Society Vol. 90. No. 3 filler, a pseudo-ductile fracture behavior is observed. Though the -A elastic modulus is a little higher, low load transfer ability from d K. Okamura. ""High-Performance SiC/SiC Composites by Improved PIP the matrix to the fibers is detrimental for strength because of the rocessing with New Precursor Polymers, " J. Nucl. Mater. 283-287. 565-9 arly failure of the matrix BY. Katoh, M. Kotani, H. Kishimoto. W. Yang, and A Kohyama, "Properties Mater,289,42-7(2001) rona, D. A. Pinto, and B. Riccardi. ""Manufacturing SiC- Fiber-Reinforced SiC Matr ed cv The incorporation of active Al filler into the matrix to enhance plymer Impregnation and Pyrolysis, J. Am. Ceram. Soc.87[7 1205-9 mechanical properties of SiC/SiC composites has been studied. (2004) During the polymer-to-ceramic conversion process, the active A D Suttor. T Erny, and P. Greil, " Fiber-Reinforced Ceramic-Matrix Compo sites with a Polysiloxane/ Boron-Derived Matrix. "J Am. Ceram Soc. 80 [7 1831- particles react with the carbon-containing pyrolysis fragments of 40(1997) the polymer and the nitrogen atmosphere. XRd pattern of the M. Takeda, Y. Kagawa, S. Mitsuno, Y Imai, and H. Ichikawa. ""Strength of a matrix alone pyrolyzed at 1200C confirms the formation of ALC3, AIN, and AlSi3. The nitridation and carburization of A mer Infiltration-Pyrolysis Process,J. Am. Ceram. Soc. 82[6]1579-81(1999) and Y filler result in volume expansion of the pyrolysis mineral resi- dues, compensating for the polymer shrinkage. Within this ohyama, Y Katoh, and K. O Elect of sic stress of 380 MPa and a maximum stress of 441 MPa with a low Derived SiC/SiC Composite, "Mater. Sci. Eng. A. 357, 37-85(002 Polymer- tudy, the maximum levels achieved are a proportionah-limit density of 1.99 g/cm. The present results clearly demonstrate the possibility of increasing stress by incorporating active fillers iAhs842359(201 into the derived matrix. Additional investigation is required to Ceram. Soc., 78 [4]835-48(I optimize the content of Al filler incorporated into the preforms to S. T. Schwab. and L. L. Snead, icrostructural Evolution and Mechanical Performances of Sic/SiC Composit btain better mechanical properties for lightweight components by Polymer Impregnation/Microwave Pyrolysis(PIMP) Process. Ceran Int, 28, References Apposed to sic/sIC Composites with a BN Interphase. "Acta Mater, 48, 4609-18 M. Berbon and M. Calal se,“ Elect of I6o0° Heat Treatment on C/IC IF. Rebillat. J. Lamon. R. Naslain. E. L. Curzio. M. K. Ferber. and T. M omposites Fabricated by Polymer Infiltration and Pyrolysis with Allylhydrido- Besmann, "Interfacial Bond Strength in SiC/ C/SiC Composite Materials as Studied polycarbosilane, "J. Am. Ceram. Soc., 85 [7] 1891-3(2002). by Single-Fiber Push-Out Tests. "J. Am. Ceram Soc.81 [4]965-78( 1998). Lfiller, a pseudo-ductile fracture behavior is observed. Though the elastic modulus is a little higher, low load transfer ability from the matrix to the fibers is detrimental for strength because of the early failure of the matrix. IV. Summary The incorporation of active Al filler into the matrix to enhance mechanical properties of SiCf/SiC composites has been studied. During the polymer-to-ceramic conversion process, the active Al particles react with the carbon-containing pyrolysis fragments of the polymer and the nitrogen atmosphere. XRD pattern of the matrix alone pyrolyzed at 12001C confirms the formation of Al4C3, AlN, and Al4Si3. The nitridation and carburization of Al filler result in volume expansion of the pyrolysis mineral resi￾dues, compensating for the polymer shrinkage. Within this study, the maximum levels achieved are a proportional–limit stress of 380 MPa and a maximum stress of 441 MPa with a low density of 1.99 g/cm.3 The present results clearly demonstrate the possibility of increasing stress by incorporating active fillers into the derived matrix. Additional investigation is required to optimize the content of Al filler incorporated into the preforms to obtain better mechanical properties for lightweight components. References 1 M. Berbon and M. Calabrese, ‘‘Effect of 16001C Heat Treatment on C/SiC Composites Fabricated by Polymer Infiltration and Pyrolysis with Allylhydrido￾polycarbosilane,’’ J. Am. Ceram. Soc., 85 [7] 1891–3 (2002). 2 A. Kohyama, M. Kotani, Y. Katoh, T. Nakayasu, M. Sato, T. Yamamura, and K. Okamura, ‘‘High-Performance SiC/SiC Composites by Improved PIP Processing with New Precursor Polymers,’’ J. Nucl. Mater., 283–287, 565–9 (2000). 3 Y. Katoh, M. Kotani, H. Kishimoto, W. Yang, and A. Kohyama, ‘‘Properties and Radiation Effects in High-Temperature Pyrolyzed PIP–SiC/SiC,’’ J. Nucl. Mater., 289, 42–7 (2001). 4 C. A. Nannetti, A. Ortona, D. A. Pinto, and B. Riccardi, ‘‘Manufacturing SiC￾Fiber-Reinforced SiC Matrix Composites by Improved CVI/Slurry Infiltration/ Polymer Impregnation and Pyrolysis,’’ J. Am. Ceram. Soc., 87 [7] 1205–9 (2004). 5 D. Suttor, T. Erny, and P. Greil, ‘‘Fiber-Reinforced Ceramic-Matrix Compo￾sites with a Polysiloxane/Boron-Derived Matrix,’’ J. Am. Ceram. Soc., 80 [7] 1831– 40 (1997). 6 M. Takeda, Y. Kagawa, S. Mitsuno, Y. Imai, and H. Ichikawa, ‘‘Strength of a Hi–Nicalon/Silicon–Carbide-Matrix Composite Fabricated by the Multiple Poly￾mer Infiltration-Pyrolysis Process,’’ J. Am. Ceram. Soc., 82 [6] 1579–81 (1999). 7 M. Kotani, A. Kohyama, and Y. Katoh, ‘‘Development of SiC/SiC Compo￾sites by PIP in Combination with RS,’’ J. Nucl. Mater., 289, 37–41 (2001). 8 M. Kotani, T. Inoue, A. Kohyama, Y. Katoh, and K. Okamura, ‘‘Effect of SiC Particle Dispersion on Microstructure and Mechanical Properties of Polymer￾Derived SiC/SiC Composite,’’ Mater. Sci. Eng. A, 357, 376–85 (2003). 9 Z. S. Rak, ‘‘A Process for Cf/SiC Composites Using Liquid Polymer Infiltra￾tion,’’ J. Am. Ceram. Soc., 84 [10] 2235–9 (2001). 10P. Greil, ‘‘Active-Filler-Controlled Pyrolysis of Preceramic Polymers,’’ J. Am. Ceram. Soc., 78 [4] 835–48 (1995). 11S. M. Dong, Y. Kotoh, A. Kohyama, S. T. Schwab, and L. L. Snead, ‘‘Microstructural Evolution and Mechanical Performances of SiC/SiC Composites by Polymer Impregnation/Microwave Pyrolysis (PIMP) Process,’’ Ceram. Int., 28, 899–905 (2002). 12F. Rebillat, J. Lamon, and A. Guette, ‘‘The Concept of a Strong Interface Applied to SiC/SiC Composites with a BN Interphase,’’ Acta. Mater., 48, 4609–18 (2000). 13F. Rebillat, J. Lamon, R. Naslain, E. L. Curzio, M. K. Ferber, and T. M. Besmann, ‘‘Interfacial Bond Strength in SiC/C/SiC Composite Materials as Studied by Single-Fiber Push-Out Tests,’’ J. Am. Ceram. Soc., 81 [4] 965–78 (1998). & 972 Communications of the American Ceramic Society Vol. 90, No. 3