Abstract
In the present work, the nanosecond-pulsed laser micro machining was applied to induce surface patterns with three different metals (i.e., titanium, aluminum as well as magnesium alloys) for producing metal-plastic hybrid (MPH) joints by injection molding. Specifically, laser variables such as the scanning speed, laser frequency, and scan repetition were altered to obtain different surface patterns. The surface morphologies were observed using scanning electron microscope (SEM). It’s found from SEM observations that due to the thermal ablation of the laser, micro patterns such as grooves and protrusions exist on all metal surfaces. However, distinct morphologies can be seen for different metals, with the most variable microstructures for the titanium alloy. Moreover, the surface wettability to the distilled water for all metal surfaces was examined with a contact angle measuring instrument. It’s shown that the contact angle characterizing the surface hydrophilicity is not necessarily related to process condition but surface morphologies. The tensile tests of the injection molded MPH joints showed that the titanium alloy surfaces with bumpy morphology facilitated forming micro-scale mechanical interlocking between the metal and the plastic, leading to enhanced MPH joint strength.
