Session: 11-19-01: Fluid Measurements and Instrumentation/Young Engineer Paper (YEP) Contest

Paper Number: 167205

Deposition Pattern Formations in a Novel Freezing-Sublimation-Based Inkjet 3D Printing Method 

Inkjet-based three-dimensional (3D) printing is widely used for fast and efficient non-contact manufacturing. One big challenge in inkjet 3D printing is the coarse printing resolution, which is essentially determined by the droplet-substrate interactions in the printing process, i.e., droplet impact, deposition, and the subsequent drying processes. The droplet impinging dynamics on solid surfaces have been extensively studied. Various dynamic phenomena have been observed, including splashing, spreading, receding, and bouncing. For a colloidal droplet impacting a solid substrate, the drop would spread to a maximum due to the dissipation of the kinetic energy of the droplet. After the spreading stage, the drop recoils back to an equilibrium shape that is determined by the surface energies of the liquid and the solid surface. The dynamics of an impacting droplet is significantly affected by liquid drop properties (i.e., viscosity, surface tension, density, velocity, and diameter) and surface conditions (i.e., roughness, wettability, and shear modulus). As a result, the resolution of inkjet-based 3D printing (i.e., printing drop footprint) would essentially depend on the ink drop volume, drop spreading cap size, and contact angle between drop and substrate. During the evaporation-based drying processes of colloidal droplets, various solid deposit patterns could form due to free surface movement, contact line dynamics, and diverse internal flow structures that may present during the evaporation processes. This has been the main source of course resolution, defect formation, and manufacturing inconsistency in inkjet-based 3D printing technologies.

These undesirable effects are due to the colloidal suspension droplets being kept in the liquid state during printing. To overcome these disadvantages, this paper presents a novel freezing-sublimation-based inkjet 3D printing concept that freezes the colloidal droplets upon impact followed by sublimation, eliminating the undesirable particle transport and fluid motions during deposition.

This study investigates how the freezing rate affects particle distribution, which directly influences resolution outcomes in 3D printing technologies. Current observations at room temperature show a "coffee-ring" effect, where particles accumulate at the droplet’s edges, leading to non-uniform patterns. By applying freezing based technology, we aim to lock the particle in place upon impact and therefore achieve uniform particle distributions, thereby enhancing printing quality.

A series of experiments will be conducted to characterize the colloidal droplet behaviors during the impinging/freezing and sublimation processes and evaluate the effects of the freezing process on droplet impinging dynamics as well as the final deposition patterns through sublimation. Advanced imaging techniques, including Atomic Force Microscopy (AFM), Environmental Scanning Electron Microscopy (ESEM), and 3D optical profilometry, plan to be employed to analyse the pattern and morphology of the lyophilized segments. Cold plasma surface treatment will be applied to the printed structures to enhance interlayer bonding, providing a more robust foundation for subsequent droplets or layers.

It is expected that the novel freezing-sublimation-based method is capable of producing much more uniform deposition patterns of each ink drop in inkjet-based 3D printing processes, thus fundamentally improving the printing quality. This work will serve as the technical and theoretical basis for the development and validation of the novel freezing-based inkjet 3D printing technique for fabricating high-quality functional structures.

Presenting Author: Yang Liu The City College of New York

Presenting Author Biography: Dr. Yang Liu is currently an Assistant Professor of Mechanical Engineering at CUNY – The City College of New York. His current research interests include multiphase flow and heat transfer in additive manufacturing, plasma-droplet interactions, blast/shock-surface interactions, high-speed multiphase interactions driven by blast/shock, aircraft icing physics and anti-/de-icing technologies, and unsteady multiphase flow in energy devices. Dr. Liu has published 1 book, 2 book chapters, 40 peer-reviewed journal papers, and more than 60 conference papers in the field of thermal fluids.

Authors:

Xiaoxiao Zhang City College of New York
Haipeng Zhang City College of New York
Jorge Ahumada Lazo City College of New York
Tai-De Li CUNY - Advanced Science Research Center
Jiazhang Chen CUNY - Advanced Science Research Center
Sheng Zhang CUNY - Advanced Science Research Center
Yang Liu The City College of New York