Effect of oxygen plasma treatment on the bonding strength of CFRP/aluminum foam composite

In the present study, the effect of plasma treatment on the bonding strength of CFRP/aluminum foam composites was investigated. CFRP and aluminum foam were surface-treated in a plasma cleaner using oxygen gas. To determine the optimal plasma treatment time, contact angles were measured as a function of treatment time. Treatment effects were determined by comparing the bending and shear strength of three cases: untreated CFRP/aluminum foam (case 1), untreated CFRP/plasma-treated aluminum foam (case 2), plasma-treated CFRP/untreated aluminum foam (case 3). Fracture surfaces of specimens from the three cases were investigated after bending and shear tests. Our results showed when the CFRP was plasma-treated using oxygen gas, and that the bending and shear strength was improved by 7.5% and 650%, respectively, compared to the case without plasma treatment. The improved bonding strength of the plasma-treated CFRP/aluminum foam composites was attributed to the increased surface roughness of the CFRP and the newly formed functionalities on the CFRP. The surface roughness of the CFRP was increased by more than 20% and two functional groups, namely, CO and OCO, were newly formed.