Investigation of the effect of phenolic resin on the performance of adhesives used in metal-metal bonding

Adhesives play a significant role in various industries and applications due to their ability to effectively and reliably bond different materials. The performance of adhesives is determined by factors such as chemical composition, curing mechanism, and application process. Adhesives are widely used in bonding metals, plastics, composites, and other materials, offering benefits such as enhancing structural integrity, reducing weight, and improving aesthetics. Bonding of metals is particularly crucial in industrial applications where traditional joining methods like riveting, welding, or screwing are not feasible. Metal adhesives typically consist of chemical components such as epoxy, acrylic, polyurethane, or phenolic resins. In this study, the focus was on the localization of an imported adhesive used in the manufacturing of aluminum honeycomb structures, which have gained increasing popularity in critical sectors such as aerospace, defense, shipbuilding, and rail systems. An alternative domestic adhesive was developed using five different commercially available phenolic resins as substitutes for the resin content in the imported adhesive formulation. The chemical and thermal properties of the five adhesives were investigated through FT-IR, TGA, and Raman analyses. The wetting ability and surface distribution of the adhesives were determined using Contact Angle and Optical profilometer devices. The effects of different phenolic resins on mechanical performance were evaluated through mechanical tests according to appropriate standard. The properties of phenolic resin can vary depending on process parameters such as pH and viscosity during production. It was found that increasing the functionality of the phenolic resin directly impacted the integrity and performance of the adhesive. A decrease in pH within the range of 13-6.5 led to an approximate 330% improvement in adhesive performance. Excessive decrease in viscosity resulted in a reduction of adhesive thickness by approximately 5.5 times, negatively affecting adhesion performance. As a result of these studies, significant steps have been taken towards the production of domestic metal-to-metal adhesives to meet the industry's needs.