Composite materials made from a porous 2D-carbon-carbon preform densified with boron nitride by chemical vapour infiltration

摘要: 2D-C-C/BN composites (with a BN volume fraction (VBN) up to 0.60) have been obtained by chemical vapour infiltration of hexagonal-BN from BF3-NH3 mixture, within the pores 2D-C-C preform made stacking carbon fabric layers which has weakly consolidated with pyrocarbon. They were tested in compression on samples directed either parallel or perpendicular load axis. In first case (p-direction), behaviour is mainly elastic (at least for high enoughVBN). Bothσ∥R andE∥ increase regularly risingVBN, as BN-layer deposited (mainly located between adjacent layers) becomes thicker,e∥R weak and progressively decreases increasingVBN. second (o-direction), stress-strain curve exhibits both pseudoplastic domains whose respective extension depends onVBN (or onVp). The related an irreversible microstructural damage interlayer C/BN filling.σ⊥R,σ⊥E andE⊥ increasingVBN decreasingVp) according parabolic laws,e⊥R much higher thane∥R. materials remain anisotropic even at highVBN. Oxidation tests air oxygen/argon mixtures) shown that 2D-C-C/BN, incompletely densified (Vp ∼ 0.10) BN, exhibit weight loss (oxidation skeleton) low temperatures BN) above 900° C. resistance enhanced (which results aVp decrease) decreasing oxygen partial pressure. It predicted good oxidation protection skeleton requires full densification 0) will be effective medium temperatures. present study could easily extended 2D-BN-BN composites.