Communications of the American Ceramic Sociery Vol 81. No. 3 20r Fig. 5. Fracture surface of the minicomposite specimen oxidized for 10 h after the tensile test. not detected during our TEM/EDS characterization. Neverthe- Sic less, it will be of importance to resolve this carbon contami- nation issue by quantifying the exact level of carbon impurity in the interphase region by more composition-sensitive tech- Sio niques such as electron energy loss spectroscopy and secondary lon mass spectroscopy. Acknowledgments: We thank Kevin Cooley and Jerry McLaughlin for performing the Cvd experiments and Dorothy Coffey for the SEM analy preparing the TEM specimens. References Matrix Composites. Edited by R. Naslain, J. Lamon, and D. Doumeingts. Wood- and P K. Liaw. Oxidation-Resistant Interface Coat ites": pp. 151-59 in Proceedings of the 10th Ann Fiber Energy Materials, Report No ORNL/FMP-96/1, Oa M. A. Borst, w. Y Lee, Y. Zhang, and P K. Liaw, "" Preparation and Char- 0.1Im eam.Soe,80间6]1591-94(199 on Chemical Vapor Deposition. The Electrochemical Society, Pennington, NJ S. Touloukian, R. K, Kirby, R E. Taylor, and T. Y.R. Lee, Thermal bon impurities, which may be present in the interphase region, EE.M. Levin, C. R. Robbins, H F. McMurdie; p 110 in Phase ansion: Nonmetallic Solids: p. 451. Plenum, New York, 1977. to the observed weak interface behavior. Minet et al. 7 observed Ceramists. E ited by M. K. Reser. American Ceramic Society, West some carbon contamination by Raman spectroscopy in Zr( coatings prepared with the same precursor chemistry. In con- JMinet, F, Langlais, and R. Naslain, " On the Chemical Vapour Deposition of Zirconia from ZrCl-H-CO -Ar Gas Mixture: IL. An Experimental Ap trast, the presence of carbon in the oxide interphase region was proach, "J. Less-Common Met, 132, 273(1987)bon impurities, which may be present in the interphase region, to the observed weak interface behavior. Minet et al.7 observed some carbon contamination by Raman spectroscopy in ZrO2 coatings prepared with the same precursor chemistry. In con￾trast, the presence of carbon in the oxide interphase region was not detected during our TEM/EDS characterization. Neverthe￾less, it will be of importance to resolve this carbon contami￾nation issue by quantifying the exact level of carbon impurity in the interphase region by more composition-sensitive tech￾niques such as electron energy loss spectroscopy and secondary ion mass spectroscopy. Acknowledgments: We thank Kevin Cooley and Jerry McLaughlin for performing the CVD experiments and Dorothy Coffey for the SEM analysis and preparing the TEM specimens. References 1 R. J. Kerans, ‘‘Control of Fiber–Matrix Interface Properties in Ceramic Ma￾trix Composites’’; pp. 301–12 in Proceedings of High Temperature Ceramic Matrix Composites. Edited by R. Naslain, J. Lamon, and D. Doumeingts. Wood￾head Publishing Limited, France, 1994. 2 D. P. Stinton, E. R. Kupp, J. W. Hurley, R. A. Lowden, S. Shanmugham, and P. K. Liaw, ‘‘Oxidation-Resistant Interface Coatings for SiC/SiC Compos￾ites’’; pp. 151–59 in Proceedings of the 10th Annual Conference on Fossil Energy Materials, Report No. ORNL/FMP-96/1, Oak Ridge National Labora￾tory, Oak Ridge, TN, 1996. 3 M. A. Borst, W. Y. Lee, Y. Zhang, and P. K. Liaw, ‘‘Preparation and Char￾acterization of Chemically Vapor Deposited ZrO2 Coating on Nickel and Ce￾ramic Fiber Substrates,’’ J. Am. Ceram. Soc., 80 [6] 1591–94 (1997). 4 E. R. Kupp, E. Lara-Curzio, D. P. Stinton, R. A. Lowden, and T. M. Bes￾mann, ‘‘CVI Processing of Minicomposites for Evaluation of Interface Coating Materials in Composites’’; in Proceedings of the 14th International Conference on Chemical Vapor Deposition. The Electrochemical Society, Pennington, NJ, in press. 5 Y. S. Touloukian, R. K. Kirby, R. E. Taylor, and T. Y. R. Lee, Thermal Expansion: Nonmetallic Solids; p. 451. Plenum, New York, 1977. 6 E. M. Levin, C. R. Robbins, H. F. McMurdie; p. 110 in Phase Diagram for Ceramists. Edited by M. K. Reser. American Ceramic Society, Westerville, OH, 1964. 7 J. Minet, F. Langlais, and R. Naslain, ‘‘On the Chemical Vapour Deposition of Zirconia from ZrCl4–H2–CO2–Ar Gas Mixture: II. An Experimental Ap￾proach,’’ J. Less-Common Met., 132, 273 (1987). h Fig. 6. TEM image of the multilayered oxide interphase of the oxi￾dized minicomposite specimen. Fig. 5. Fracture surface of the minicomposite specimen oxidized for 10 h after the tensile test. 720 Communications of the American Ceramic Society Vol. 81, No. 3