Pyrocarbon/silicon carbide (PyC/SiC){sub n} and boron nitride/silicon carbide (BN/SiC){sub n} nanoscale multilayers have been fabricated by pressure pulsed-CVI (P-CVI), pyrocarbon, boron nitride and silicon carbide were deposited from C{sub 3}H{sub 8}, BCl{sub 3}-NH{sub 3} and MTS-H{sub 2} gas precursors, respectively. Such nanoscale multilayers were used as interphases in SiC/SiC minicomposites, manufactured by P-CVI and reinforced by Hi-Nicalon fibres. The stress-strain behaviour under tension at room temperature, and the lifetime in static fatigue at high temperatures in air were investigated. The minicomposites exhibited improved mechanical properties and oxidation resistance in comparison to their counterparts having a single layer of pyrocarbon or boron nitride as interphase. The multilayered interphases allows the control of fibre/matrix interactions and the oxidation resistance. (orig.) 11 refs.
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Bertrand et al. (1998) studied this question.