May 1999 Influence of lsothermal CVD and CV Conditions on the Deposition Kinetics and Structure of BA 1195 let composition and the mass flow rate seem to be very im- ress in Adanced Materials and Mechanics. Edited by T. Wang and T.W t to obtain both the best uniformity and the best organ The use of diffusion screens especially could be gen- IR. A Lowden. K harz, and N. L d to other systems, to improve the control of the depo re C (4) A thermal post-treatment at nder vacuum in Chemical Vapor Co-deposition of C and Si, Ci-n"J Phys. 11, 3, 549-5 proves the organization of bn that he posited via CVd 20T. Matsuda, "Stability to Moisture for Chemically Vapour-Deposited Bo- 3-58(1989 only. However, the 10-20 nm of the layer, and it seems to ally very Strength of a Silicon Carbide/Silicon Nitride Composite, Mater. Res. Soc poor organization and the release of impurities 型PC:250.239492 is. and S.L. Suib rength of CVI SiC/BN/SiC Comp Acknowledgments: The authors acknowledge R Herbin, for her help ran.Eng. Sci. P 2R. Naslain, O. Dugne, A Guette, J. Sevely, C. Robin Brosse, J.-P. Roche nical contribution. The authors also are indebted to S. Goujard and C and J. Cotteret, ""Boron Nitride Robin-Brosse(SEP) for the supply of materials and fruitful discussions. " N. Ricca, A. Guette, G. Camus, and J M. Jouin, ""SiC (ex-PCS) MAS Composites with a BN Interphase: Microstructure, Mechanical Properties and see Ref. 9, pp. 455-6 SS. Prouhet, G. Camus, C. Labrugere, A, Guette, and E. Martin, "Mechanical England. 1971 interphase ?ation of Si-C(o) Fiber/Sic (CVD) Matrix Composites with a BN- in Brittle Composites w Manth: "Models of Fiber Debonding and Pull-out Chemistry of SiC/BN Dual-Coated Nicalon-Fiber-Reinforced Glass-Ceramic Mech.Maer,9,139-63(199 3A. G. Evans and D B The Mechanical Behavior of Ceramic Khin, J 2567-83(1989) Matrix composites,". Am. Ceram. Soc. 7 (5)1329-39(199A\ e, Ak Sevely, J-P. Rocher, and J. Cotteret, "Interface Characterization by TE ES R. W. Davidge."Fibre- Ceramics, "Composites(Guildford UK and SIMS in Tough SiC (ex-PCS) Fibre-SiC (CVI) Matrix Composites with a J.J. Brennan, "Interfacial Chemistry and Bonding in Fiber-Reinforced Glass -Vapor-Infiltrated Ceramic and Glass-Ceramic Matrix Composites, "Mater. Sci. Res, 21, 387-99(1986) Mater.sc.Eng.A,A126,203-23(1990 of Fibre- Matri 29B. A. Bender and T L Jessen, "A Comparison of the Interphase Develop Composites. An ent and Mechanical Properties of Nicalon and Tyranno SiC Fiber-Reinforced Electron Microscopy Study, J. Mater. Sci., 22, 3148-60(1987) The Netherlands). Edited by aux obtenus, Ph D. Thesis. Universite d orleans, Orleans, France. 995 rfaces in Ceramic Matrix the 13th International Conference on Chemical C. Vix-Guterl, J. Lahaye, and P. Ehrburger, " Reactivity in Oxygen of a chemical Society Proceedings, Vol. 96-5. Edited by T M. Best The rmostrustuera ciep t r, pa a2is-32 an ingh ne rature neram wood. Allendorf, McD. Robinson, and R. K. Ulrich. Electrochemical shing Limited, Abington, Cambridge, England, 1993 mical va Nitride Interphase in Ceramic Fiber Preforms: Discussion of Some Aspects of Metal Matrix Composites, "J Mater. Sci., 23, 311-28(1988 the Fundamentals of the Isothermal Chemical Vapor Infiltration Process, " J. M. P Bacos, Carbon-Carbon Composites: Oxidation Behavior and Coat- J. Phys.,3,1895903(1993) Patibandla and K L. Luthra, "Chemical Vapor Deposition of Boron 2s. Goujard, L. Vandenbulcke, and H. Tawil, "Oxidation Behavior of 2D Polylayer Coatings, "Thin Solid Films, 252, 120-30(1994) Vandenbulcke and G. Vuillard, "Structure of Deposits-Process Rela tionships in the Chemical Vapor Deposition of Boron, "J. Electrochem. Soc. 3A. W. More, M. B, Dowell, E R. Stover, and L D. Bentsen, " Oxidation J. M. Blocher Jr,""Structure/Property/Process Relations in Chemical Vapor Deposition CVD, J. Vac. Sci. Technol. 11, 680-86(1974) Stinton, T M. Bes- Ceramic Matrix Composites, Mater. Res. Soc. Symp. Proc., 120, 157-62 nann, and O J. Schwarz, "Nextel/SiC Composites Fabricated Using Forced L. Heraud, R. Naslain, and J. M. Quenisset, "Procede de Fabrication d't P. Dupel, R Pailler, and X. Bourrat, "Pulse-CVD and Infiltration of Pyro- Matrice Ceramique a Tenacite Amelioree, "Fr. Pat. No arbon in Model Pores with Rectangular Cross-Sections; Part Il, Study of the Infiltration, J. Mater. Sci., 29, 1056-66(1994)- (a)C. Droillard, "Elaboration et Caracterisation de Composites a Matrice 3G. Lacrambe, "Fabrication et "Graphitation'du Nitrure de Bore Obtenu par SiC et a Sequence C/SiC", Ph D. Thesis No 913. Bordeaux Uni se Temperature", Ph D. Thesis N eparoux, L. Vandenbulcke, V. Serin, and J. Sevely, " The Interphase terphases, "Mater. Res. Soc. Symp. Proc., 365, 371-76(1995 and Interface Microstructure and Chemistry of Isothermal/isobar Vandenbulcke and S. Goujard, "Multilayer Systems Based on B, B.C, Vapour Infiltration SiC/BN/SiC Composites: TEM and Electron Energy Loss SiC and SiBC for Environmental Composite Protection" pp. 1198-204 in Prog 595-602(1inlet composition and the mass flow rate seem to be very im￾portant to obtain both the best uniformity and the best organi￾zation. The use of diffusion screens especially could be gen￾eralized to other systems, to improve the control of the deposit structure. (4) A thermal post-treatment at 1000°C under vacuum im￾proves the organization of BN that has been deposited via CVD only. However, the reorganization is limited to the outermost 10–20 nm of the layer, and it seems to require an initially very poor organization and the release of impurities. Acknowledgments: The authors acknowledge R. Herbin, for her help in the preparation of the samples and the manuscript, and Y. Boussant, for his technical contribution. The authors also are indebted to S. Goujard and C. 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