A two-step strategy to graft CNTs onto titanium/CFRP interface for interfacial enhancement.

• Proposed a facile and eco-friendly modification method to graft CNTs onto titanium surface. • The interface between titanium and PEEK was interlinked by "coordination bridges" and CNTs network. • The interfacial shear strength between modified titanium and PEEK had an increment of 205.4 %. • The flexural strength (210.0 %), and ILSS (95.2 %) of modified CF/PEEK-Ti composites were significantly enhanced. The primary challenge of fiber metal laminates (FMLs) is the insufficient interfacial adhesion between metal and resin, which impedes the realization of the full potential. To address this issue, a two-step strategy has been proposed: firstly, via the cerium coordination-based approach, followed by grafting carbon nanotubes onto the titanium surface. This modification enhances the interfacial behavior between titanium sheets and polyetheretherketone (PEEK), resulting in increased roughness and wettability on the titanium surface, facilitating tight contact between PEEK and titanium sheets while reducing defects at the interface. Compared to CF/PEEK-sandblasted Ti, the modified CF/PEEK-Ti composites exhibit significantly enhanced interfacial shear strength, equivalent flexural strength, and interlaminate shear strength with an increase of 205.4 % (39.4 MPa), 133.3 % (1434.3 MPa) and 95.2 % (93.7 MPa), respectively. Additionally, the failure mode has shifted from interfacial failure to cohesive failure. The interface enhancement mechanism can be attributed to the synergistic effects of coordination bonding, mechanical interlocking, and multiple interactions. This facile two-step modification method demonstrates the potential to enhance the interfacial properties of CF/PEEK-Ti composites. [Display omitted] [ABSTRACT FROM AUTHOR]