Comparison of interfacial adhesion of hybrid materials of aluminum/carbon fiber reinforced epoxy composites with different surface roughness

This study investigated the effect of surface roughness for improving interfacial adhesion in hybrid materials with aluminum (Al)/carbon fiber reinforced epoxy composites (CFREC). The surface roughness of the Al was controlled using different types of sanding paper and varied sanding times. Al surface roughness were evaluated using static contact angle (CA) and 3D surface scanning measurements after the different sanding processes. Lap shear strength (LSS) tests were performed to evaluate the interfacial adhesion between CFREC and Al with the different Al surface treatments. The theoretical maximum cohesive strength (TMCS) and work of adhesion, W-a between the Al and CFREC were correlated with surface energy of epoxy adhesive and LSS. The surface energy of epoxy adhesive and TMCS between CFREC and Al exhibited a proportional relationship. The TMCS was also directly related to the LSS between Al and CFREC. It was found that an optimum sanding process yielding a R-a, 1.4 mu m Al surface roughness exhibited the highest work of adhesion, as well as the largest LSS and TMCS for hybrids of Al-CFREC. Proper Al surface control in these materials shows real promise for enhancing the mechanical properties for aerospace, automotive and other practical applications.