Low-Temperature Plasma Treatment of Aluminum for Improved Surface Bonding

In this study, the influence of low-temperature plasmas on the surface bonding performance of aluminum (Al) alloys was explored by means of surface treatment. Then, response surface method was employed to optimize the processing technology of low-temperature plasmas, and the interactivities of three factors, namely input power ( p ), spay gun-to-specimen surface distance ( d ) and specimen movement velocity ( v ), with the surface energy of Al alloys were analyzed. The results showed that when p = 800 W, d = 10 mm and v = 2 mm s −1 , the processing technology of low-temperature plasmas was better, and the surface energy reached 75.96 mJ m −2 , which was 147% higher than that before treatment. Moreover, the wettability was evidently improved. After the treatment with low-temperature plasmas, both the varieties and quantity of oxygen-containing functional groups increased, accompanied by enhanced surfactivity of Al alloys. Besides, the tensile shear strength and paint layer adhesion of adhesive bonding Al alloy specimens were apparently elevated by 73.14 and 41.3%, respectively. According to the chemical bonding theory, a key factor contributing to the improved bonding strength of Al alloys lies in the increased varieties and quantity of oxygen-containing functional groups on their surface.