Friction Lap Joining of Thermoplastic Materials to Carbon Steel

摘要

Dissimilar material joining of polyamide 6 and polyethylene plates to a plain carbon steel (SPCC) plate was performed using friction lap joining. The polyamide 6 and SPCC plates could be directly joined by friction lap joining, whereas the polyethylene and SPCC plates could not. Corona discharge treatment of the polyethylene surface enabled the joint formation with SPCC. The tensile shear fracture load of the SPCC/polyamide 6 and SPCC/corona-discharge-treated polyethylene joints increased with the joining speed up to 600 mm min~(-1), beyond which it decreased. These joints were fractured at the base material of the plastic plate at optimal joining speeds in the tensile shear test. Continuously joined interfaces of these materials were observed via cross-sectional microstructure analysis. Transmission electron microscopy and selected area diffraction patterns indicated that these materials were joined through the surface oxide layer of SPCC composed of Fe_3O_4. The relation between the tensile shear fracture loads and the results of XPS analysis indicated that polar groups such as amide, hydroxyl, and carboxyl groups on the plastic surfaces were highly effective for joint formation of the SPCC/plastic joints.