Mechanical properties, electrical conductivities and lightning strike damage behaviors of CNT/graphene modified carbon fabric reinforced composites

By coating aqueous dispersions of carbon nanotubes (CNTs) and multilayer graphene (MLGs) on the carbon fiber (CF) fabrics, CNT-hybrid and CNT-MLG co-hybrid fabrics and their composites were prepared. The mechanical studies show that CNT hybridization only has little effect on the mechanical properties of the composites, while CNTs-MLGs co-hybridization caused a 41.6% decrease of the interlaminar shear strength. The conductivity studies show that the conductivities of the CNT and CNT/MLG hybrid fabrics increased by 7.78% and 10.2%, respectively. The conductivities through thickness direction (σ_z) of the corresponding composites increased by 472% and 124% compared to the control, reaching 0.79 S/cm and 0.31 S/cm, respectively. Their in-plane conductivities increased by 43.2% and 17.8%, respectively. The lightning strike damage (LSD) studies in Zone 2A show that the delamination area and damage depth of the CNT hybrid composite are 240 mm² and 0.343 mm, which decreased by 62.3% and 35%. The delamination area of CNT/MLG co-hybrid fabric composite increased by 79.3%, while its damage depth reduced by 42.2%. As a comparison, the delamination area of the another control with a low σ_z of 0.011 S/cm significantly increased to 30.5 times and its damage depth increased by 150%. Mechanism analysis shows that for this kind of composites, the increase in σ_z reduced both the delamination area and damage depth, while the increase in fabric conductivity reduced the damage depth but expands the delamination area in the shallow layer.