Effects of temperature profiles of microwave curing processes on mechanical properties of carbon fibre-reinforced composites

The microwave curing of composites is a promising technology to manufacture the composite components faster than conventional thermal curing. But how the shortened temperature profiles, which determine the duration of microwave curing processes, will affect the outcome of cured parts is still not clear. In this study, the effects of microwave curing processes governed by different temperature profiles on the mechanical properties of carbon fibre-reinforced composite material have been experimentally investigated. The results showed that microwave-cured composites have similar curing kinetics as the conventional thermally cured ones, and they were better in interlaminar shear and flexural strengths than thermally cured ones, while slightly lower in tensile and compressive strengths. The increase in heating rates in the temperature profiles enhanced the compressive and flexural strengths of the composites within a certain range, but moderately compromised the tensile and interlaminar strengths; the reduction in holding time can decrease the mechanical performances of the composites moderately, except for the interlaminar shear strength. The micrographs of the fracture surfaces after the interlaminar shear tests demonstrated the enhancing effect of microwave curing on the fibre-matrix interfacial bonding, but this effect can be slightly compromised when increasing the heating rates. These results could serve for the tradeoffs between reducing the manufacturing time and preserving the mechanical properties of the microwave-cured composites.