Laser-Ablated Interlaced Micropatterns on CFRP and Ti-64 Plates to Improve Single-Lap Adhesive Joining Strength

This study investigated the relationship of the joining strength between interfacial microstructures and the hygrothermal aging characteristics of CFRP and Ti-6Al-4V (Ti-64). Interlaced micropatterns of interweaved strips and seamless structures were fabricated on CFRP and Ti-64 plates using fiber lasers. When the laser power and scan speed were set at 27.8 W and 100 mm/s, the Ti-64 and CFRP plates, which had the lowest WCA values of 49.5 ± 1.2° and 16.6 ± 2.8°, were used for the processed interlaced micropatterns, respectively. Before the aging test, the shear force of single-bonded Ti-64/CFRP specimens with unpatterned, interweaved strips, and seamless structures was 2580.5 ± 150.5 N, 4009 ± 90.1 N, 3773.6 ± 120.8 N, respectively. After the aging test for 30 days, the shear force of the Ti-64/CFRP specimens with unpatterned, interweaved strips, and seamless structures was 2408.8 ± 65.3 N, 3880.4 ± 160 N, 3340.5 ± 96.7 N, respectively. The key factor in enhancing the tensile strength was the mechanical interlocking at the interface around the bonded area. Therefore, the laser-ablated interweaved strips were remarkably capable of enhancing the joining strength of heterogeneous materials and resisting severe environmental changes.