Hybrid additive manufacturing (3D printing) and characterization of functionally gradient materials via in situ laser curing.

This paper presents a hybrid additive manufacturing (3D Printing) process for fabricating functionally gradient materials. A multi-axis robot was integrated with microextrusion, picojet, and fiber laser systems to deposit conductive traces of different materials. Laser and furnace curing mechanisms were investigated to evaluate their effect on grain morphology and electrical resistivity of the traces. An increase in the number of laser passes resulted in microstructure evolution from a powder-like to densely packed structure for different materials (Ag, Ni, and C). The laser curing mechanism offered lower resistivity and rapid curing times (< 1 min) compared with furnace curing (> 2 h). Optimal sintering parameters were obtained for 4-pass laser at 18 W with comparable resistivity with bulk materials. Localized infiltration (doping) of nanoparticle silver within the micro-extruded carbon trace demonstrated a significant enhancement in electrical properties (two orders of magnitude reduction in resistivity). The energy dispersive x-ray spectroscopy (EDS) mapping of the infiltrated traces displayed uniform dispersion of nano-particulate silver within the carbon matrix. Multilayer-multi-material (MLMM) traces deposited displayed distinctive morphology of each constituent material based on in situ laser curing. Scanning electron microscopy revealed distinctive microstructure and graded elemental composition of different layers (FGM) based on targeted laser sintering of individual materials. The versatile hybrid AM platform provides a basis to fabricate functionally gradient materials (FGMs) for electronic components with several applications. [ABSTRACT FROM AUTHOR]