High-strength silicon carbide fibre-reinforced glass-matrix composites

Abstract

Silicon carbide fibre-reinforced glass-matrix composites have been fabricated and tested. Two fibre forms, a 140/~m diameter monofilament and a 10/~m diameter filamentary yarn, were incorporated into a matrix of borosilicate glass. The hot-pressing fabrication procedure resulted in fully dense unidirectionally reinforced specimens with excellent flexural strength and fracture toughness over the temperature range 22 to 700 ~ C. In addition, composite thermal expansion was found to be nearly independent of fibre orientation indicating that multiaxially reinforced composites should be readily fabricable without the occurrence of extensive cracking.

Effects of Processing Parameters on Properties of SiCp/Al Composites

“…When the green compact of the composite is hot-pressed at a temperature only below the solidus temperature, SiC particles are clustered in the matrix as impurities. Correspondingly, the Al/SiC interfacial bond is rather weak, resulting in the poor properties including the strength, elongation and elastic modulus of the composite [7]. As the green compact is hot-pressed and hot-extruded both at low temperatures, SiC particles disperse homogeneously in matrix.…”

“…However, the exposed SiC particles in the matrix indicate that the interfacial bond is not strong enough to resist the tensile, and the plastic deformation of Al matrix dominates the fracture behavior of the composite. Thus, the strength of the composite is low while the ductility is high [7]. As the green compact is hot-pressed at low temperature and hot-extruded at a temperature little higher than the solidus temperature, the SiC/Al interfacial bond is strong with high strength Al matrix, resulting that much higher stress is needed to break the SiC/Al interfaces.…”

“…Due to the strong interfacial bond, the volume of Al matrix participating in deformation reduces and the Al matrix near to the depositions undergoes severe plastic deformation. As a result, the strength and elastic modulus of the composite are high while the elongation to failure decreases lightly [7]. In the case that the green compact is hot-pressed and hot-extruded both at higher temperatures, the SiC/Al interfacial bond formed by atomic diffusion is very strong while the strength of matrix decreases.…”

“…In the case that the green compact is hot-pressed and hot-extruded both at higher temperatures, the SiC/Al interfacial bond formed by atomic diffusion is very strong while the strength of matrix decreases. The fracture process occurs mainly in Al matrix and fewer broken or de-bonded SiC particles are found in the fracture surfaces, reflecting that the strength of the composite is low while the elongation is high [7].…”

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

“…Fiber coating was a serendipitous discovery by Prewo and Brennan while using Nicalon T M fibers to reinforce a borosilicate matrix [21,22]. By applying a thin coating to the reinforcing fiber, a relatively weak interface bond is created between the coated fiber and the matrix.…”