Suppression of gravity effects on metal droplet deposition manufacturing by an anti-gravity electric field

Abstract

Droplet-based 3D printing is a promising technique for metal forming in space, owing to the advantages of dispensing without large-scale energy equipment or customized materials. However, the extreme environment in space, for example microgravity, would change the printing mechanisms significantly compared with those on the ground, which hinders the application of droplet-based 3D printing in space. To develop a droplet-based 3D printing technique suitable for space manufacturing, the droplet deposition behavior under microgravity should be physically simulated in normal gravity environment. Here, a novel experimental system comprising an anti-gravity electric field was developed to suppress the gravity effects on droplets deposition by manipulating the droplets to perpendicularly deposit on a vertical substrate. Parameter mappings of regulation voltage were established based on theoretical modeling and experimental results. The controllable region of flight trajectories locates in the top half of the electric field. The charging voltage shows better regulation accuracy than the deflection voltage. Under the manipulation of the electric field, droplets deposit on the substrate and solidify into regular morphologies. The solidified contour and adhesion force of the deposited droplets were measured. Finally, a freestanding pillar and a bending wall structure were fabricated. This work demonstrates the feasibility and effectiveness of the anti-gravity electric field in manipulating droplets to perpendicularly deposit on vertical surfaces against gravity, and forming 3D structures.