Structure and chemistry of fibre-matrix interfaces in silicon carbide fibre-reinforced glass-ceramic composites: an electron microscopy study

Abstract

Silicon carbide continuous fibre-reinforced glass and glass-ceramic matrix composites showing high strength and fracture toughness have been studied using thin-foil transmission electron microscopy and scanning transmission electron microscopy (AEM). The outstanding mechanical behaviour of these materials is directly correlated with the formation of a cryptocrystalline carbon (graphite) reaction-layer interface between the fibres and the matrix. A solid-state reaction involving relatively rapid diffusion of silicon and oxygen from fibre to matrix correlates well with the experimental observations. Silica activity in the glass-ceramic matrix is suggested to play a primary role in the ability to control the chemical reaction which creates the graphitic interface. AEM results are used to comment upon a possible mechanism for the high-temperature embrittlement behaviour noted for these materials when they undergo rupture in an aerobic environment.