Laser transmission welding of dissimilar transparent thermoplastics using different metal particle absorbents

The laser absorbents are necessary in the process of laser transmission welding (LTW) transparent thermoplastics. It has been demonstrated that metal absorbents in LTW have great advantages for achieving a high quality joint, though the decomposition of thermoplastics is difficult to control. Metal particle absorbents with different melting point, including magnesium zinc alloy particles (MZAP), zinc particles (ZnP) and tin particles (SnP), were introduced to investigate the weld morphologies, tensile process and bonding characteristics of the weldments in the present study. The hot-pressing equipment was used to embed the metal particle absorbents in thermoplastic. Lap welding experiments were carried out to investigate the effects of metal particle absorbents and welding parameters (laser power and welding speed) on shear force and the weld morphologies. The discrepancy of shear force-displacement curves, microscopic morphology and element distribution between different weldments were investigated. Compared with the ZnP and SnP absorbents, the weldments with MZAP absorber had the highest shear force of 662 N under the condition of laser power of 35 W and welding speed of 8 mm/s. The underlying reason was attributed to the minimal thermoplastic decomposition and the good interfacial interaction.