Interfacial bonding performance of KH550 and CNTs modified Fe and NiTiNb-SMA/Epoxy resin

This study employed Sikadur-330CN as the epoxy matrix. To enhance interfacial bonding, a surface modification method using carbon nanotubes (CNTs) combined with the silane coupling agent KH550 was applied to Fe-SMA and NiTiNb-SMA wires. The interfacial bond strength of both SMA/epoxy specimens was measured via uniaxial pull-out tests, focusing on the effects of SMA type, bond length and surface modification method on the interfacial failure mode and bond strength. Subsequently, analyses of surface roughness, morphology, XPS, and FTIR before and after pull-out were conducted to investigate the mechanism by which the CNTs modification combined with KH550 affects the Interfacial Bonding Performance. Finally, numerical simulation of the interfacial mechanical behavior was performed using a cohesive zone model to further analyze the stress distribution during the pull-out process of both SMAs.The results show that within the effective bond length range, the average interfacial bond strength of Fe-SMA and NiTiNb-SMA specimens modified with CNTs alone reached 1.04–1.29 times and 1.05–1.22 times that of unmodified specimens, respectively. When modified with both KH550 and CNTs, the strength increased to 1.07–1.42 times and 1.09–1.36 times, respectively. This study provides experimental evidence and design references for enhancing the performance of Fe-SMA and NiTiNb-SMA in practical applications.