Surface treatment of CFRP composites by Ar⁺ irradiation to improve bonding strength between aluminum and CFRP composites

The effect of surface treatment of carbon fiber reinforced plastic (CFRP) composites on the T-peel strength and the shear strength between CFRP and aluminum panels was studied. The surface of the composite panel was treated with Ar⁺ irradiation under oxygen environment. The optimal Ar⁺ ion dose was determined by measuring the changes of contact angle and surface energy as a function of ion dose. T-peel tests and SLS tests were performed using irradiated CFRP/aluminum specimens and unirradiated CFRP/aluminum specimens to determine the treatment effect by Ar⁺ irradiation under oxygen environment on the T-peel strength and shear strength of CFRP/aluminum composites. The results showed that contact angle on the surface of the composite panel was reduced from ∼80° to ∼8° and the surface energy increased from 31 ergs/cm² to 72.4 ergs/cm² with an ion dose of 10¹⁷ ions/cm². T-peel strength and shear strength are significantly affected by the surface treatment of composite panel. T-peel strength and shear strength improved 650% and 56%, respectively, when the treatment was made with an ion dose of 10¹⁶ ions/cm². SEM examination showed that the improvement of bonding strength was attributed to the uniform spread and fracture of epoxy adhesive.