Directionally induced high-density secondary interaction for enhancing the bonding reliability of titanium alloy and CFRTP via functional Schiff base-contained polymer

For lightweight applications, the interfacial bonding reliability determines the service life of Ti–6Al–4V titanium alloy (TC4)/carbon fiber reinforced thermoplastic (CFRTP) joints. Traditional joining methods limit their applications. In this study, a functional Schiff base-contained polymer was successfully synthesized to modify the TC4 surface. The results indicated the directionally induced high-density complexation between the synthesized Schiff base and the titanium atom from the TC4 sheet and the secondary interaction between the synthesized Schiff base-contained polymer and CFRTP matrix occurred, which improved the bonding reliability of the TC4/CFRTP joint. The combination of the high-density secondary interaction and synergistic effect between the functional groups enhanced the interfacial bonding strength by 287 % to 38.73 MPa. This was remarkably higher than the bonding strength improved by 46 % to 14.64 MPa via the introduction of micromolecule Schiff base that consists of same functional groups. The significant enhancement of the interfacial bonding reliability was thus achieved. These results were beneficial to future research to improve the reliability of metal-CFRTP hybrid joints.