Effect of the Surface Treatment on the Strength of Mixed Adhesive in Single Lap Joint Aluminum

Abstract

Adhesive is a joining technology which is used in many transportation industries. The surface treatment and adhesive thickness are the important parameter which affect the adhesive joint strength. The mixed adhesive between silyl modified polymer (SMP) and epoxy (EP) adhesive is proposed to join aluminum. Aluminum alloy 5083 was used as adherent in this work. Its surface was cleaned using the sandblasting (SDB) method and then treated using chemical treatment of chromic-sulphuric acid (CSA) etch. The aluminum adherends were mixed adhesive joined with the standard of ASTMD 1002 in single lap joint (SLJ) type. The composition variation of mixed adhesive was 100%EP, 75%EP:25%SMP, 50%EP:50%SMP, 25%EP:75%SMP and 100%SMP. The adhesive thickness was varied of 0.2 mm, 0.4 mm and 0.6 mm. The strength of mixed adhesive was determined by the single lap shear test. The mixed adhesive joint without surface treatment was also performed for comparison. The surface with chemical treatment was finer than that without chemical treatment. It leads the adhesive strength of the joint with chemical treatment was lower than that of the joint without chemical treatment for all adhesive thickness levels. The adhesive thickness of 0.2 mm was the best thickness due to the achievement of the strongest adhesive strength. The small addition of SMP to EP adhesive will increase the adhesive joint strength.