Studies of laser joining PA66- and PEEK-based composites with titanium alloy through constructing interlocking structures at joint interface

Fiber reinforced composites have been widely applied in the fields of aviation, aerospace, automotive, shipping and others to achieve weight reduction while ensuring the sufficient strength of parts owing to their extraordinary properties. However, the connection between these thermoplastics and metals remains a concern. Laser joining process, emerged as an advanced technology, has been recently investigated to obtain high-quality joining of thermoplastics and metals. In our work, laser joining process was explored and optimized to realize high-performance joining between various thermoplastics and titanium alloy with the focus on structure design, micro-defects elimination and interlocking structures construction. Results indicated that the maximum fracture strength of 41.5MPa and over 60MPa was respectively obtained between titanium alloy and PA66-based or PEEK-based composites. High-low temperature alternating aging tests revealed that the laser joining produced dissimilar joints between titanium alloy and PEEK-based composites showed excellent thermal stability. Particularly, a novel method of constructing strong micro-mechanical interlocks between titanium alloy and continuous carbon fiber reinforced Polyetheretherketone was proposed and demonstrated through laser joining process. The formed interlocking structures at the interface contributed to high bonding quality of the joints. The utilized laser-based joining process is a universal method for joining thermoplastics and various metals such as titanium alloys, steel and aluminum alloys to achieve high bonding performance at the interface. Moreover, such laser joining technology shows high flexibility and can be applied even in complex situations for on-site repairing of critical components of infrastructures.