Investigation of electrochemical oxidation process time and glycidoxypropyl trimethoxy silane coating in glass fiber reinforced composite adhesive bonded joints

In this study, the effects of the electrochemical oxidation treatment duration and the coating with glycidoxypropyltrimethoxysilane (GPTMS) on the bond strength of aluminum joints bonded with glass fiber-reinforced adhesive were investigated. Glass fibers were subjected to electrochemical oxidation in a sulfuric acid solution for 3, 6, and 9 minutes, then chopped into lengths of approximately 10 mm before being incorporated into the adhesive. The surfaces of the bonded aluminum materials were prepared by chemical etching, and single-lap joints were fabricated using the fiber-reinforced adhesive. The fabricated joints were subjected to three-point bending tests, and the failure loads were determined. Additionally, GPTMS coating was applied to the surfaces of oxidized glass fibers, and joints were similarly fabricated and tested. The results demonstrated that the oxidation treatment of the glass fibers improved the bond strength, and that this improvement was dependent on the oxidation duration. Furthermore, it was found that the silane coating process enhanced the joint performance by approximately 10–13% after the oxidation treatment. In addition, the obtained results were supported by contact angle measurements and scanning electron microscopy (SEM) analysis. This study highlights the effect of glass fiber surface modification on adhesive bonding performance.