Strategic dual laser 3D printing of structural metal-plastic hybrid materials

Abstract

Metal-plastic hybrids are emerging as a new challenge in multi-material 3D printing. Here, we provide a novel printing method for strategically bonding and printing metal-plastic hybrids using dual lasers with different wavelengths in a single integrated process. This bottom-up process enables three-dimensional freeform deposition while creating an ideal metal-plastic interface. In particular, our research has shown that the strategic selection of a laser with high energy absorption efficiency for the target material is a key technology for material hybridization. It was revealed that the laser, when irradiated directly onto the interface, partially crosslinks the plastic to form dense phases and induces a chemical reaction with oxygen active species on the metal surface, e. g., an intermediate oxide layer of Al-O-C, leading to the formation of a strong metal-plastic interface. Interestingly, this laser-induced metal-plastic interface, sophisticatedly controlled at the monolayer thickness level, exhibited a distinctive near-interface failure mechanism that developed crack paths along the near interface. Moreover, the competition between crack propagation and pore coalescence in each dense and porous printed layer formed a synergetic interphase, resulting in strong and tough mechanical functions. Our findings can guide the development of metal-plastic hybrids for a variety of industrially important applications.