A study on the peel and shear strength of aluminum/CFRP composites surface-treated by plasma and ion assisted reaction method

This study investigates the effect of surface treatment of aluminum and CFRP on the peel strength and the shear strength of aluminum/CFRP composites. The surface of the aluminum was treated using DC plasma and the surface of the CFRP was treated by Ar+ IAR (ion assisted reaction) method under oxygen environment. Optimal plasma treatment conditions (treatment time, ratio of acetylene gas to nitrogen gas) and the optimal Ar+ ion dose were determined. In order to determine the treatment effect on the peel strength and the shear strength of aluminum/CFRP composites, T-peel tests and SLS (single lap shear) tests were performed using four types of specimens: (1) plasma-treated aluminum/irradiated CFRP specimen, (2) plasma-treated aluminum/untreated CFRP specimen, (3) untreated aluminum/ irradiated CFRP specimen, (4) untreated aluminum/untreated CFRP specimen. The results showed that the optimal plasma treatment time and the ratio of acetylene gas to nitrogen gas were 30sec and 5:5, respectively. The optimal Ar+ dose of CFRP was in a range of 1015–1016 ions/cm2. The results also showed that the bond strength (T-peel strength and shear strength) of plasma-treated aluminum/irradiated CFRP specimen was largest and that of untreated aluminum/untreated CFRP specimen was smallest. The untreated aluminum/irradiated CFRP specimen produced better bond strength than the plasma-treated aluminum/untreated CFRP specimen. It was found from SEM examination that cohesive failure of epoxy adhesive occurred for specimens surface-treated by plasma or ion irradiation while adhesive failure occurred for untreated specimens.