Experimental study on the influences of different surface treatment processes and adhesive type on the aluminum adhesive-bonded joint strength

Surface roughness obtained from different preparation processes such as sanding, shot blasting, and sand blasting were considered in this study. The effects of surface roughness on shear strength of single-lap adhesive joint were examined. 2024-T3 aluminum sheets were cut into standard pieces and then sanded with seven sandpapers with different mesh, shot blasted for four different duration times and sandblasted under four different pressures. Pairs of prepared surfaces were attached using Araldite 2015 adhesive with high viscosity and HPL1012/HPH112 epoxy adhesive with low viscosity. Results show that the ultimate lap shear strength of the sanded samples initially increase and then decrease as surface roughness is increased. The lap joint strength continuously increases as the surface roughness of shot blasted and sand blasted samples are increased. In sanding, the optimum surface roughness is different for both high and low viscosity adhesives. However, for shot blasting and sand blasting, the optimum surface roughness is the same for both adhesive types. The maximum ultimate lap shear strength of joints for both types of adhesives obtained for sand blasting under 0.6 MPa pressure with 0.6 μm surface roughness.