Elucidation of role of carbon fibers on joining of metal to composite

Weight reduction in the various application fields has propelled to the forefront in investigations of combining metal with polymer. Different from other studies, this work focused on exploring the effect of carbon fibers on the thermal joining of metal to composite. Three plastics with different fiber contents including pure polyether-ether-ketone (PEEK), short carbon fibers reinforced PEEK (SCF/PEEK), and continuous reinforced PEEK (CF/PEEK) were chosen to join to the 6061aluminum alloy using a fiber laser. Results showed the thermal transfer was fostered along the carbon fiber orientation due to a higher thermal conductivity, decreasing the heat accumulation at the interface. However, the existence of carbon fibers also hindered the spreading of plastics on the aluminum alloy surface. This led to a smaller adhesion width and lower tensile-shear force of joints. In addition, the tensile-shear strength of joints prepared with carbon fibers was enhanced owing to lower thermal expansion coefficient, which improved the thermal shrinkage and reduced the stress concentration at the interface. Ultimately, the role of carbon fibers during laser joining of aluminum alloy to plastics was explained, clarifying the bonding mechanism of two materials.