Probing Ink-Powder Interactions during 3D Binder Jet Printing Using Time-Resolved X-ray Imaging

Area of Science:

• Materials Science
• Additive Manufacturing
• Fluid Dynamics

Background:

• Capillary-driven ink infiltration in 3D binder jet printing dictates printing resolution and green strength.
• A comprehensive understanding of infiltration kinetics is currently incomplete.
• Alumina powder beds serve as a model system for studying liquid penetration.

Purpose of the Study:

• To investigate the kinetics of capillary-driven ink infiltration in a porous powder bed.
• To visualize and analyze the heterogeneous behavior of liquid front propagation.
• To compare experimental findings with existing infiltration models.

Main Methods:

• Utilized high-resolution in situ synchrotron radiography for time-resolved imaging.
• Employed a static drop-on-demand inkjet printer to dispense liquid.
• Tracked liquid migration and particle interactions using fast synchrotron X-radiography with phase-contrast imaging at 500 Hz.

Main Results:

• Observed heterogeneous temporal and spatial behavior in wetting area increment and leading edge propagation.
• Demonstrated that mean infiltration kinetics align with modified Washburn equation models.
• Incorporated adjustments for liquid drop spreading and modified bed porosity in the models.

Conclusions:

• The study provides detailed insights into the complex kinetics of liquid infiltration in 3D printing powder beds.
• Experimental results validate and refine existing infiltration models, enhancing their predictive capabilities.
• Understanding these dynamics is crucial for optimizing 3D binder jet printing processes.