Structure, mechanical property, electrical conductivity and lightning strike damage behavior of graphene/carbon nanotube co-modified CFRPs

Developing structural composites with integration of lightning strike resistance is one of the trend of developing new composites. In this paper, a composite co-modified with graphene and carbon nanotubes was prepared. Its microstructure, mechanical properties, electrical conductivity and lightning-strike properties were studied. Morphology study shows that the conductive fillers are mainly distributed in the interlayer and the adjacent intralaminar regions, while much less in the deep intralaminar regions. The composite has 0° flexural strength of (1538±86) MPa and 0° interlaminar shear strength of (107.0±1.0) MPa. Three laminates of 2 mm, 3 mm and 4 mm thickness were prepared for studying the electrical conductivity and lightning-strike properties. The in-plane conductivity of the composites is around 100 S/cm. The conductivity through thickness direction are 0.128 S/cm, 0.094 S/cm and 0.088 S/cm, respectively. The lightning-strike test shows that the total damage area of the three thickness samples is similar. The deep damage area decreases, while the damage depth increases with the decrease in conductivity through thickness direction. The damage mode is mainly the ablation damage of fiber and resin. No obvious delamination is found. The minimum flexural strength and the corresponding retention rates of the flexural strength and modulus of the damaged 2 mm thick laminate at the damage center are 782 MPa, 75% and 59.2%, respectively. The average flexural strength retention rates of the damage centers of the 2 mm and 3 mm thick laminates reached 87.4% and 87.2%, respectively. Their damage depths are only around 0.3 mm and 0.4 mm respectively.