Enhancing Ultrasonic Welding Joints of CF / PEEK Composites and Aluminum via Pre‐Deposition of a PEEK Layer Onto the Metal Substrate

ABSTRACT The integration of metals with carbon fiber composites has become a pivotal area of research in lightweight design, with ultrasonic welding emerging as a promising joining technique. In this study, a novel surface pretreatment process for aluminum alloy (Al) is proposed to enable effective ultrasonic welding with CF/PEEK composites. The Al surfaces were pretreated using either grit‐blasting or laser ablation, followed by depositing a PEEK layer onto its surface via a hot‐pressing process. Experimental results revealed that applying appropriate surface pretreatments to the Al substrate significantly enhanced its bonding strength with the PEEK coating layer, thereby improving its fusibility and weldability at the welding interface. Optimizing the Al surface pretreatment process yielded substantial improvements in joint quality, achieving a maximum single‐lap shear strength (LSS) of 21.4 MPa. This study presents an innovative approach to enhancing the structural integrity of ultrasonically‐welded hybrid joints, effectively addressing challenges arising from material property mismatches.