Recrystallization of Nickel-coated Carbon Fibres

Abstract

CARBON fibres of high strength and stiffness have recently been developed at these laboratories and elsewhere^1,2. To exploit these mechanical properties in composites at high temperatures, the fibres must remain compatible with the matrix material. In a survey of several matrix materials, in which the strength and structure of metal-coated fibres were examined after various heat treatments, some interesting effects were observed with nickel-coated fibres. It was found that the strength of nickel-coated fibres was drastically reduced after heat treatment for 24 h at temperatures above about 1,000° C. X-ray diffraction studies were therefore performed to investigate the differences between the strong and the weak fibres. Two types of carbon fibre were investigated: a, “carbonized”, by controlled pyrolysis of polymer fibre up to 1,000° C, and b, “graphitized”, by further treatment up to 2,700° C.