Feasibility of friction stir joining of polycarbonate to CFRP with thermosetting matrix

Friction stir joining (FSJ) process was preformed to produce hybrid joints between amorphous thermoplastic (polycarbonate) and carbon fiber-reinforced plastic (CFRP) with thermosetting matrix in lap configuration. The influence of the pin plunging depth (within the CFRP) and the tool shoulder plunging depth (within the polycarbonate) was studied to determine the suitability of FSJ process for these types of materials. Single-lap shear tests were conducted to determine the mechanical characteristics of the joints. Results indicated that the strength of the joints was significantly affected by the tool plunging depth, while it was marginally influenced by the tool shoulder plunging depth. The toughness of the joints is greatly influenced by the tool shoulder plunging depth. Morphological characterization and fracture surface analysis clarified the influence of these process parameters on the mechanical characteristics of the joints. The results from this study highlight the high mechanical properties of the joints (up to 12 MPa) due to the replacement of the original epoxy matrix of the composite by means of the polycarbonate.