Influence of Adherend Surface Roughness on the Adhesive Bond Strength

Abstract Surface treatment of the adherends prior to adhesive bonding plays an important role in the enhancing of strength and durability of bonded joints. In this work, an investigation on effect of adherend surface roughness on adhesive bond strength was performed. Single strap joints with different adherends (mild steel and aluminium) bonded with an epoxy resin (Araldite(r) 2015) were tested. The adherend surface was treated by mechanical abrasion process using an emery paper. Contact angle measurement and SEM analysis to understand the wettability and the failure mechanism of the joints were performed. It was found that an optimum surface roughness exists for a maximum bonding strength and the roughness range depends on the adherend material. The joint strength changes are associated not only simply by the increased bonding area, surface texture or mechanical interlocking, but also by the chemical characteristics of the surface and the chemical bond between them.

摘要 胶接前对被粘物进行表面处理，对提升胶接接头的强度与耐久性具有重要作用。本研究针对被粘物表面粗糙度对胶接强度的影响展开系统探究。实验采用环氧树脂（Araldite® 2015）作为胶黏剂，制备了软钢与铝合金两种不同被粘物的单搭胶接接头并开展测试。通过砂纸机械打磨的方式处理被粘物表面，借助接触角测量与扫描电子显微镜（Scanning Electron Microscope, SEM）分析，对接头的润湿性与失效机制进行了研究。结果表明，可获得最高胶接强度的最优表面粗糙度区间因被粘物材质而异。接头强度的变化不仅与胶接面积增大、表面形貌改变或机械互锁效应直接相关，还与被粘物表面的化学特性以及二者之间的化学键合作用密切关联。