Electrochemical pre-treatment of aluminum alloy in environmentally friendly medium : Parameter optimization and bonding strengthening mechanism

Hu, Qifan and Ge, Zhenghui and Pang, Kai and Zhu, Yongwei and Hou, Xiaonan (2026) Electrochemical pre-treatment of aluminum alloy in environmentally friendly medium : Parameter optimization and bonding strengthening mechanism. Thin-Walled Structures, 219 (Part A): 114226. ISSN 0263-8231

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Abstract

The electrochemical treatment of adhesive surfaces in neutral salt solutions is a promising novel method for improving the bonding performance of aluminum alloys. However, the mechanism through which this treatment improves interfacial bonding strength remains poorly understood. This study systematically investigates the relationship among electrochemical parameters, microstructure, property evolution, and the bonding strength of thin-walled aluminum adhesive joints. Multi-scale characterization techniques were employed to elucidate the strengthening mechanism from the perspectives of chemical bonding and mechanical interlocking. The results demonstrated that a current density of 0.8 A·cm−2 applied for 100 s increased the bonding strength by 170% compared to untreated joints. Furthermore, the effect of electrochemical treatment, sandblasting, and grinding on the surface characteristics and bonding properties was compared. XPS and FTIR analyses revealed that the electrochemical treatment significantly increased the surface density of hydroxyl groups, which promoted the opening of epoxy rings and the subsequent formation of covalent bonds. This finding confirms the critical role of chemical bonding in enhancing interfacial strength. Eventually, a qualitative model was developed to illustrate the mechanism by which electrochemical treatment enhances the adhesive performance of aluminum alloy joints. These insights are valuable for exploring the potential application of electrochemical treatment to thin-walled, lightweight alloy components.