Effect of Process Conditions on ILSS of Carbon Fiber / Epoxy Composites Stepwise Curing with Low-energy E-Beam

Electron beam (E-Beam) curing technology has become increasingly applied in modern composite manufacturing industry. Comparing to conventional thermal curing, E-Beam curing provides an efficient solution to fabricate integrated composite structures of a wide range of dimensions with a minimal consumption of energy. Currently, the majority of E-Beam curing systems use high-energy E-Beams. However, high construction cost, high radiation, and low operational flexibility hinder the further expansion of applications of this technique. In this study, a prototype of novel dual-emitter low-energy E-Beam curing system was built, which was energy efficient and radiation safe. The minimum E-Beam energy that could satisfy the stepwise curing of carbon fiber/epoxy composites was investigated through detailed analysis of effects of the irradiation dose, the post cure temperature, and roller materials on the inter-laminar shear strength (ILSS) with microstructure characteristics. The results indicate that carbon fiber/epoxy (CF/EP) composites can be adequately cured by 150 keV E-Beams using our system, with an optimal irradiation dose which could enhance the ILSS as largely as 44.6 % (from 34.2 MPa to 61.7 MPa). It was also observed that laminates irradiated by 50 kGy and post-cured at 180 °C would reach the optimized ILSS of 64.7 MPa. An anti-sticking silicon rubber with low surface energy could effectively reduce interlayer defects, resulting in higher ILSS.