Enhancing Bonding Properties of Steel‐Composite Joints: Effects of Surface Treatments and Adhesive Selection

Steel‐composite joints being a crucial part of complex architectures requiring adhesion/bonding are an area of increasing interest. Such adhesion depends on several factors including the choice of adhesives and the employed surface treatments. However, there isn't any study systematically reporting the influence of the mentioned factors. This work analyzes the effects of surface treatments and adhesive types on the adhesion and performance of steel‐composite joints. Untreated, mechanically treated, acid‐etched, and anodized steel specimens were joined with composites employing three distinct adhesives, such as Aremco 2310, polyurethane (PU), and silicone. Microscopic analysis revealed that untreated samples had a smooth surface, whereas treated samples had rough abraded lines, pores, and oxide layers. Surface contact angles also indicated higher surface energies owing to oxidization. Lap shear revealed that anodized treatment offers about 45% higher strength than untreated specimens. Among different adhesives, Aremco 2310 had the maximum shear strength, followed by a decreasing trend towards PU and silicone. Aremco/anodized composite entailed 17% higher Izod Impact strength than untreated ones, and the highest among all specimens proving the combination suitable. Hence, the investigation highlights the necessity of surface treatments and the selection of suitable adhesives to tailor the performance of steel‐composite joints.