Electrical curing of carbon fibre composites with conductive epoxy resins

Direct electric cure (DEC) was used to cure carbon fibre-reinforced polymers (CFRPs). We show that the energy consumption for curing is significantly reduced, with the judicious placement of contact electrodes, by almost twelve-fold, compared to autoclave curing, and threefold compared to oven curing (0.84, 10.0, and 2.64 kW). CFRP samples of an epoxy matrix with 0-3 wt% carbon black (CB) was used to increase matrix conductivity, and the effect of this variation on the curing and mechanical properties was determined. Subsequently, the concentration with the highest flexural strength, a CFRP with 2 wt% CB was prepared, to study the effects of four different contact arrangements (Top-Bottom, Outside-Outside, Outside-Inside, Inside-Inside) under high pressure (about 2 MPa). Top-Bottom mode shows the best performance, here the electrical current flows through the ply stack perpendicular to the fibre direction. This CFRP has similar mechanical properties as samples manufactured by a range of traditional curing methods. Although the degree of cure (DOC) was reduced by 3–7 %, dependent on the placement of the electrical contacts, the through ply cures showed uniform and high degrees of cure. We show that DEC, thus provides a low capital investment solution to high-quality composite manufacture, facilitating market access for small enterprises, as part sizes and curing times are not limited by oven size nor oven thermal mass.