N‐heterocyclic Carbenes as Adhesion Promoters on Aluminum Alloy 6061

ABSTRACT The adhesive industry faces significant challenges in developing effective, simple, safe, and economical surface treatment methods to achieve strong bond strengths and long‐term durability. Conventionally, surface treatments have relied on hexavalent chromium compounds and strong acids, which pose serious safety and health concerns. In this study, we explore the use of a non‐toxic organic molecule known as an N‐heterocyclic carbene (NHC) for adhesion promotion applications. The functionalization of aluminum alloy 6061 (AA6061) with an NHC was achieved using an immersion process and confirmed through X‐ray photoelectron spectroscopy (XPS) and laser desorption/ionization (LDI) spectrometry. Accelerated electrochemical corrosion and environmental corrosion chamber studies demonstrate that NHC–functionalized AA6061 has higher corrosion resistance compared to untreated AA6061. The impact of NHC functionalization on the adhesive joint strength and durability was also evaluated by a single‐lap‐shear test following up to >900 h of continuous exposure in a corrosion chamber. This simple immersion‐based approach shows great promise for enhancing the adhesion strength of AA6061‐epoxy bonding using surface organic chemistry.