2.5D printing of a yield-stress fluid

Area of Science:

• Materials Science
• Fluid Dynamics
• Additive Manufacturing

Background:

• Direct ink writing (DIW) is a versatile additive manufacturing technique.
• Understanding the printability of yield-stress fluids is crucial for DIW applications.
• The first deposited layer significantly impacts overall print quality and substrate adhesion.

Purpose of the Study:

• To investigate the direct ink writing of a model yield-stress fluid.
• To analyze the deposition morphologies of the first printed layer.
• To identify controllable parameters for achieving specific film structures.

Main Methods:

• Utilized direct ink writing (DIW) with a model yield-stress fluid.
• Varied operational parameters: ink flow rate, substrate speed, and writing density.
• Analyzed deposition morphologies and film thickness control.

Main Results:

• Observed diverse deposition morphologies dependent on operational and material parameters.
• Identified a specific morphology forming flat films, controllable irrespective of fluid properties (as long as yield-stress is present).
• Demonstrated real-time control over film thickness within a significant range ([Formula: see text] mm) and the ability to print films with thickness gradients.

Conclusions:

• Direct ink writing of yield-stress fluids can produce controllable flat films.
• Film printing fidelity is governed by the interplay between yield-stress and capillary forces.
• This research enables precise control over film thickness and gradients in additive manufacturing.