Influence of high-temperature exposure on mechanical properties of zircon-silicon carbide composites

Abstract

Thermal stability of zircon matrix composites uniaxially reinforced with either uncoated or BN-coated silicon carbide monofilaments was determined by measuring mechanical properties and fibre-matrix interfacial characteristics in the as-fabricated state and after annealing treatments between 25 and 1430 °C for times up to 100 h. Composites reinforced with uncoated silicon carbide filaments retained their mechanical properties and fibre-matrix interfacial characteristics up to 1350 °C for 100 h. In contrast, composites reinforced with BN-coated silicon carbide filaments displayed changes in mechanical properties and fibre-matrix interfacial characteristics when annealed beyond 1300 °C for 100 h. Both types of composite displayed a significant reduction in strength and toughness after annealing at 1430 °C for 20 h. These results are consistent with changes in fibre-matrix interfacial properties, and with changes in mechanical characteristics of zircon matrix and silicon carbide filament as a result of the high-temperature annealing treatments.