Radiation processing of carbon fibre-reinforced advanced composites

Abstract

Carbon fibre-reinforced advanced composites are being used for a variety of structural applications, because of their useful mechanical properties, including high strength-to-weight ratio and corrosion resistance. Thermal curing of composite products results in internal stresses, due to the mismatch of the coefficients of expansion of the tools and the composite products. Because radiation curing can be done at ambient temperatures, the possibility that the residual stresses might be absent, or much lower in the radiation-cured products, originally led to the start of work on radiation curing of advanced composites at AECL's Whiteshell Laboratories in Pinawa, Canada, in 1985. Research work during the last two decades has shown that advanced composites can be radiation-cured with electron beams or γ radiation. Many of the advantages of radiation curing, as compared to thermal curing, which include curing at ambient temperature, reduced curing time, improved resin stability and reduced volatile emissions, have now been demonstrated. The initial work focussed on electron curing of acrylated epoxy matrices. Since then, procedures have been developed to radiation cure conventional aerospace epoxies, as well. Electron beam cured advanced composites are now being developed for use in the aircraft and aerospace industry. Repair of advanced composite structures is also possible using radiation curing technology. Radiation curing work is continuing at Pinawa and has also been done by Aerospatiale, who have facilities for electron curing composite rocket motor casings and by Chappas and co-workers who have electron cured part of a boat hull. In this paper, the work done on this emerging new technology by the various groups is briefly reviewed.