820 Journal of the American Ceramic Sociery-Kahraman ef al Vol. 80. No. 7 ceramic matrix composite. The data were obtained for Nicalon/ ings on Interfaces in Composites 193-204. Edited by C. G. Pantano and CAS-Il over the range from 20 to 1000oC. GIe did decrease urgh, PA, 1990. moderately with increasing temperature(as does the bulk ma Evaluating Trans- trix), but no evidence of an interphase oxidizing effect on crack er.Scl.Let,1u12]51l-55(1982) growth could be found. Even after fracturing and being ex- posedonthefracturesurfaceduringcool-down,interfacesnearF2lugsmodeglaminationandTRansverseCracking.compos,.Mater20 bond strength. The more open side showed higher bond Publishers, Dordrecht, Nether strength(and a flatter fracture surface42 as expected ). Cracks would not grow in the oxidizing environment at GI values Bradt, D P H New York, 1973 htly below Grc(for a 3 h exposure time), and oxidation did ng Time-Dependent Failure Charact not occur on the part of the fracture surface which was cracked Mater. Sci. 7(10) 1137-45(1972) but not widely opened during the test 2D P. williams and A G. Evans, ""Simple Method for Studying Slow Crack Acknowle ch would not have occurred without the 26A. G. Evans and S M. Wiederhorm, ""Crack Propagation and Failu tride at Elevated Te nd University of Petroleum an onle enck ies arad wr e: p. 4 3-9 edited byg l Peat chap mat and an New York. 1969. E.R. Fuller, Jr, "Fracture Mechanics Applied to Brittle Materials: References P man. American Society for Testing and Materials, Philadelphia, PA, 1979 1-56 in High Temperature/High Performance Composites, Edited 20. Sano,"'A Revision of the Double Torsion Technique for Brittle Mate Lemkey, S.G. Fishman, A G. Evans, and J.R. Strife. Materials Re- rials, J. Mater. Sci, 23, 2505-1l(i988) J O. Stiegler, "Structural Ceramics R& D, " Adv. Mater. Ceram Soc., 60 [7-8]33841(197 Processes,138355-61(1990 3C. G. Annis and J S. Cargill, Fracture Mechanics of Ceramics: pp. 737 ties for Com- 44. Edited C. Bradt, D. P H. Hasselman, and F. F. Lange. Plenum Press, New York, 1973 3P. S. Leevers, Crack Front Shape Effects in the Double Torsion Test, J. R B. Tait, P. R. Fry, and G.G. Garrett, " Review and Evaluation of the with High Tensile Strength, J. Am. Ceram. Soc., 59[7-8] Double Torsion Technique for Fracture Toughness and Fatigue Testing 324-27(1976) "T- L. Mah, M. G. Mendiratta, A.P. Katz, and K S. Mazdiyasni,"Recent D. K Shetty and A. v. virkar, mination of useful ri Specimens, J Am. Ceram Soc., 61[1-2]93-94 Am. Ceran Soc. Bull, 66 (2]304-18(1987 of Fiber matrix 33J. B Schutz, "Test Methods and Analysis for Glass-Ceramic Matrix Com nic ma- triNicalon Fiber Composites"; Pp, 349-60 in Proceedings of the Ce R. Shercliff, and M. F. Ashby, ""Delamination, Fiber Composite Ceramics. Edited by r. e. Tressler of Ceramic Matrix Composites, Acta Metall, G L. Messing, C G. Pantano, and R. E. Newnham. Plenum Press, New York, 417]195970(1993). D. A. W. Kaute, H. R. Shercliff, and M. F. Ashby, 9R. I Kerans, R S. Hay, N I. Pagano, andT. A Parthasarathy "The Role of m. Ceram. Soc. BulL. 68 [2]42942(1989) Reinforced Brittle Matrix Composites, J. sci.29,3857-%6( E Y Luh and A G. Evans, "High Temperature Me Transverse 啊Pmm.D Modified R. L Stewart, K. Chyung, M. P. Taylor, and R F. Cooper, "Fracture of pp.87-108 in ASTM Special Te Publica- mics of Ceramics. Edited by r c. Bradt, D H. Grande, J F. Mandell, and K CC. Hong, Fiber-Matrix Bond M. Huger, D. Fargeot, and C. Gault, "Ultrasonic Characterization of chanisms in Nicalon/C/SiC Composites, "J. Am. Ceram. Soc., 77[10] sci,23,311-28(1988) 2554-60(1994) 42R. Kahraman, "" Influence of Fiber-Matrix Interphase on High Temperature "Oxidation Mechanisms and Ki Ph.D. the 3J. F. Shackelford, Introduction to Materials Science for rs. Mac uzzi and R. naslain, *Oxidation Mechanisms and Kinetics of ID- g Development and Failure of Fiber SCorning Inc, private communication to Dr. J. F. Mandell, 1992 einforced Ceramic matrix C Ph. D. Thesis, Massachusetts Institute A. G. Evans, ' Stress nidirectional Ceramic Matrix Composite, "J. Am. Ceram, Soc.. 77 R. A. Shimansky, H. T. Hahn, and N J. Salamon, ""Symposium Proceed- 0(19941820 Journal of the American Ceramic SocietpKahraman et al. Vol. 80, No. 7 ceramic matrix composite. The data were obtained for Nicalod CAS-II over the range from 20” to 1ooo”C. GI, did decrease moderately with increasing temperature (as does the bulk ma￾trix), but no evidence of an interphase oxidizing effect on crack growth could be found. Even after fracturing and being ex￾posed on the fracture surface during cool-down, interfaces near the less open side of the fracture surface showed no increase in bond strength. The more open side showed higher bond strength (and a flatter fracture surface4* as expected). Cracks would not grow in the oxidizing environment at GI values slightly below GI, (for a 3 h exposure time), and oxidation did not occur on the part of the fracture surface which was cracked but not widely opened during the test. Acknowledgments: This research would not have occurred without the composite materials supplied by Corning. Inc., their help is acknowledged. We also wish to acknowledge the donation of high-temperature testing equipment by Instron Corp. Montana State University is acknowledged for its support. R. Kahraman also acknowledges King Fahd University of Petroleum and Minerals. References ‘K. M. Prewo, “Glass and Ceramic Matrix Composites-Present and Fu￾ture”; pp. 145-56 in High Temperarurdfigh Performance Composites. Edited by F. D. Lemkey, S. G. Fishman, A. G. Evans, and I. R. Strife. Materials Re￾search Society, Pittsburgh, PA, 1988. 2D. R. Johnson and J. 0. 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