Improvement of interlaminar mechanical properties of CARALL based on nanofiller interface reinforcement and other fabrication techniques

Improvement of interlaminar mechanical properties in carbon fiber aluminum laminates (CARALL) fabricated by carbon fiber reinforced plastic (CFRP) layers combined with aluminum alloy layers was studied. Various toughing methods including acid etching treatment and patterned structure manufacturing on the surfaces of aluminum alloy layers, and addition of nanofiller, i.e., VGCF, to the interface of CFRP and aluminum alloy through powder method, were employed to improve the mechanical properties of CARALL. Experimental results of double cantilever beam (DCB) tests indicated the improvement on the interlaminar mechanical properties of Mode-I fracture from much higher critical load P _c and fracture toughness GIC when using the acid etching treatment and VGCF addition. The acid etching treatment sample with VGCF 20 g/m ² possesses the highest GIC, which is 41 times higher than that of the sample without any treatment. The patterned structure manufacturing on the surfaces of aluminum alloy layers can further improve the fracture properties of CARALL without adding VGCF. While VGCF was included in CARALL specimens, the patterned structure manufacturing has a minor effect on the Mode-I interlaminar mechanical properties. Crack propagation and fracture surface have also been observed to interpret the improvement mechanism.