Thermal stability of silicon carbide fibres

Abstract

THE potential of high strength silicon carbide fibres for use in composite materials¹ depends on their thermal stability; specifically on the ability to retain their strength after exposure to the temperatures of composite fabrication and subsequent service. Aveston² has reported a marked reduction in the strength of such fibres after they have been exposed to high temperatures. This has not been observed in single crystal and bulk polycrystalline silicon carbide which exhibits no degradation of mechanical strength with temperature^3,4. We have studied the influence of high temperature on the tensile fracture strengths of pyrolytically deposited silicon carbide fibres from several sources. We found that their strengths after exposure were considerably higher than may have been expected from the previously published data.