SOLID STATE ELSEVIER Solid State ionics 141-142(2001)541-548 elsevier. com/locate/ssi Synthesis of highly tailored ceramic matrix composites by pressure-pulsed CVI R.R. Naslain',R. Pailler, X. Bourrat, S Bertrand, F. Heurtevent, P. Dupel F Lamouroux Laboratory for Thermostructural Composites, UMR-5801(CNRS-SNECMA-CEA-UBD, University Bordeaux 1, 3 Allee de La boetie, 33600 Pessac. france Abstract Pressure-pulsed chemical vapor infiltration(P-CVD) is a new processing technique to produce ceramic matrix composites (CMCs)(C/C, C/SiC and SiC/SiC) from gaseous precursors with highly tailored interphases and matrices. P- sed to control the microtexture of pyrocarbon deposited from hydrocarbon in a porous body. It is also used to form (PyC-SiC) or(BN-SiC) interphases with elementary layer thickness of a few nanometers. Finally, P-CVI is an efficient way to produce self-healing matrices comprising mechanical fuse layers (PyC or BN) and glass-former layers(B13C2 or/and SiC). The resulting model or real composites display an oxidation resistance, in air at 600-700oC and under load which is improved by two orders of magnitude. C 2001 Elsevier Science B V. All rights reserved Keywords: Chemical vapor infiltration; CVI; Ceramic matrix composite; Multilayered ceramics; Carbon; Silicon carbide; Boron nitride 1. Introduction matrix. The interphase has several key functions including load transfer, matrix crack deflection Ceramic matrix composites(CMCs) are promis- (mechanical fuse function)and diffusion barrier. The ing materials for structural applications at high tem- best interphase materials might be those with a lay- peratures. They comprise a fiber architecture ered crystal structure, such as graphitic carbons (I embedded in a ceramic matrix often deposited by rocarbons or PyC) or hexagonal boron nitride, or chemical vapor infiltration(CVD) from a gaseous with a multilayered microstructure, such as(PyC precursor. The most common are the C/C,C/Sic SiC), or(BN-SiC)n, the layers being parallel to the and SiC/SiC composites(the fibers being specified fiber surface [2, 5 ] The concept of multilayered ce first)[1.CMCs tough when the fiber/matrix ramics has been extended to the matrix itself, with a (FM) bonding is neither too strong nor too weak view to increase the oxidation resistance. In CMCs That bonding is controlled through an interphase deposited on the fiber prior to the infiltration of the sists of thin layers of ceramics acting as mechanical fuses and thin layers of glass formers [6, 7] Pressure-pulsed chemical vapor infiltration (P Corresponding author. LCTS, UMR-47(CNRS-SEP-UBI) Domaine Universitaire. 3 Allee de La boetie. 33600 Pessac CVI) is a novel technique for depositing ceramics france.Tel:+33-556-84-4700;fax:+33-556-84-1225 ithin the porosity of a substrate, such as a fiber E-Inail address: naslainalcts u-bordeaux. fr(R. R. Naslain) preform In P-CVl, a given sequence of elementary 0167-2738/01/S- see front matter C2001 Elsevier Science B V. All rights reserved. P:S0167-273801)00743-3Solid State Ionics 141–142 2001 541–548 Ž . www.elsevier.comrlocaterssi Synthesis of highly tailored ceramic matrix composites by pressure-pulsed CVI R.R. Naslain), R. Pailler, X. Bourrat, S. Bertrand, F. Heurtevent, P. Dupel, F. Lamouroux Laboratory for Thermostructural Composites, UMR-5801 CNRS-SNECMA-CEA-UB1 , Uni ( ) Õersity Bordeaux 1, 3 Allee de La Boetie, ´ ´ 33600 Pessac, France Abstract Pressure-pulsed chemical vapor infiltration P-CVI is a new processing technique to produce ceramic matrix composites Ž . Ž .Ž . CMCs CrC, CrSiC and SiCrSiC from gaseous precursors with highly tailored interphases and matrices. P-CVI can be used to control the microtexture of pyrocarbon deposited from hydrocarbon in a porous body. It is also used to form Ž .Ž . PyC–SiC or BN–SiC interphases with elementary layer thickness of a few nanometers. Finally, P-CVI is an efficient n n way to produce self-healing matrices comprising mechanical fuse layers PyC or BN and glass-former layers B C Ž. Ž 13 2 orrand SiC . The resulting model or real composites display an oxidation resistance, in air at 600–700 . 8C and under load, which is improved by two orders of magnitude. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Chemical vapor infiltration; CVI; Ceramic matrix composite; Multilayered ceramics; Carbon; Silicon carbide; Boron nitride 1. Introduction Ceramic matrix composites CMCs are promis- Ž . ing materials for structural applications at high tem￾peratures. They comprise a ceramic fiber architecture embedded in a ceramic matrix often deposited by chemical vapor infiltration CVI from a gaseous Ž . precursor. The most common are the CrC, CrSiC and SiCrSiC composites the fibers being specified Ž first 1 . CMCs are tough when the fiber . w x rmatrix Ž . FM bonding is neither too strong nor too weak. That bonding is controlled through an interphase deposited on the fiber prior to the infiltration of the ) Corresponding author. LCTS, UMR-47 CNRS-SEP-UBI , Ž . Domaine Universitaire, 3 Allee de La Boetie, 33600 Pessac, ´ ´ France. Tel.: q33-556-84-4700; fax: q33-556-84-1225. E-mail address: naslain@lcts.u-bordeaux.fr R.R. Naslain . Ž . matrix. The interphase has several key functions including load transfer, matrix crack deflection Ž . mechanical fuse function and diffusion barrier. The best interphase materials might be those with a lay￾ered crystal structure, such as graphitic carbons py- Ž rocarbons or PyC or hexagonal boron nitride, or . with a multilayered microstructure, such as PyC– Ž SiC or BN–SiC , the layers being parallel to the .Ž . n n fiber surface 2,5 . The concept of multilayered ce- w x ramics has been extended to the matrix itself, with a view to increase the oxidation resistance. In CMCs displaying a self-healing behavior, the matrix con￾sists of thin layers of ceramics acting as mechanical fuses and thin layers of glass formers 6,7 . w x Pressure-pulsed chemical vapor infiltration P- Ž CVI is a novel technique for depositing ceramics . within the porosity of a substrate, such as a fiber preform. In P-CVI, a given sequence of elementary 0167-2738r01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. PII: S0167-2738 01 00743-3 Ž