Improvement in Adhesion Behavior of Aluminum Due to Surfaces Treatment with Arc Discharge

Adhesive bonding of aluminum requires activating of part surfaces to improve the adhesion process. In the present study, The influence of arc discharge on the adhesion of epoxy, polyurethane and acrylic adhesives to aluminum is investigated whereby the influence of arc discharge parameters (amperage, frequency, work distance and treatment speed) on the improvement of adhesive strength are examined. Changes in surface topography and chemical composition of the surfaces are also identified, using Scanning Electron Microscopy (SEM) and Energy Disperse X-ray analysis (EDX).The results indicated that, two-components epoxy and polyurethane adhesives enable high adhesive strength, in comparison to thermosetting of single component epoxy. Similar behavior was determined for cold setting of two-component acrylic adhesive. Cohesive rupture was found in the two component epoxy and acrylic adhesives to be predominant. The rupture occurred in the layer nearby the aluminum surface whereby the rupture took place cohesively in the center of the adhesive layer in the polyurethane adhesive joint. The adhesion improvement achieved can be attributed to increasing roughness, complete removal of organic layers and reduction of inorganic magnesium oxide layers