Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 145995

145995 - Understanding the Dynamic and Thermal Behaviors of Colloidal Droplets Toward a Novel Freezing-Based Inkjet Printing Concept 

Inkjet-based additive manufacturing (AM) technology has been widely used for manufacturing complex and advanced structures, with urgent growing demand from various industries. Conventional inkjet-based 3D printing creates layer-by-layer structures by jetting colloidal suspension droplets onto a substrate with subsequent evaporation and deposition. While this inkjet technology can provide fast and efficient non-contact manufacturing with additional design and material flexibilities, it suffers from drawbacks such as coarse resolution, lack of adhesion, manufacturing inconsistency, and uncertainty of final part mechanical properties. Such undesired effects arise from droplet placement error, uncertainty in droplet spreading, and uneven deposit distribution after solvent evaporation due to the liquid nature of the colloidal suspension droplets. The impact, spread, and deposition of liquid colloidal droplets are significantly affected by the liquid properties, inner flow patterns, and droplet-substrate interactions. To overcome this issue, a novel freezing-based inkjet 3D printing concept is proposed in this project, as inspired by recent progress in freezing 3D printing techniques and new research findings on the rapid self-similar shape evolution in ice sublimation and similar evaporation/sublimation rates of liquid and ice drops. In this work, the deposition is achieved by freezing the colloidal droplets upon impact, followed by a sublimation process, thus eliminating the undesired overspreading, particle transport, and fluid motions during deposition. This project explores the feasibility of adopting the freezing-sublimation mechanism to achieve more precise control of drop spreading and deposition in broader inkjet 3D printing applications. To demonstrate the feasibility of this novel freezing-based inkjet AM concept, the first objective is to understand the fundamental physical details of the dynamic and thermal behaviors of colloidal droplets during impact, deformation, and freezing processes, which govern the deposit distribution size and uniformity. This research (i) quantify the dynamic behaviors and thermal evolutions of colloidal droplets during impact, deformation, and freezing/solidification processes under different ambient and surface conditions; (ii) extract the dynamic and thermal time scales of colloidal droplets during the impact, deformation, and freezing processes; and (iii) examine and document the final deposit extent and morphologies formed under different freezing conditions, i.e., ambient and surface temperatures, humidity, and hydrophobicity. This project establishes the technical and theoretical foundation for a long-term research program focused on the development and validation of the novel freezing-based inkjet 3D printing technique tailored for fabricating high-quality functional structures.

This project will advance knowledge about the dynamic and thermal behaviors of colloidal droplets in the novel freezing-based inkjet AM concept in the following ways: (i) new experimental evidence of the dynamic and thermal time scales of colloidal droplet impact, deformation, and freezing as the basis for designing efficient and high-throughput freezing-based inkjet AM technologies; (ii) fundamental knowledge about the dynamics, transient heat transfer, and phase change processes of colloidal suspension droplets in inkjet-based 3D printing techniques; and (iii) evaluation of the effects of freezing conditions (i.e., ambient temperature and humidity, surface temperature, and hydrophobicity) on the dynamic and thermal behaviors of colloidal droplets and the resultant deposit characteristics. Taken together, findings from this proposed research will build the basis for a long-term research program on the novel freezing-based inkjet 3D printing concept.

Presenting Author: Xiaoxiao Zhang City College of New York

Presenting Author Biography: Xiaoxiao (Eva) is a Ph.D. student in the Department of Mechanical Engineering at The City College of New York. Her research is focused on the dynamic and thermal behaviors of colloidal droplet in freezing-based inkjet 3D printing processes.

Authors:

Xiaoxiao Zhang City College of New York
Haipeng Zhang City College of New York
Yang Liu The City College of New York