3D ceramic additive manufacturing process based on colloidal assembly

Ceramic additive manufacturing has not reached the same level of technological maturity as polymer or metal 3D printing. Yet, unlike conventional techniques such as pressing, extrusion or molding, it helps create complex tools and parts at lower costs and in a shorter time.

Conventional additive manufacturing processes require the use of organic additives, most of which are made with petrochemicals (plasticizers, binders, etc.). However, although they enable 3D shaping, they require an additional debinding step before sintering the parts to remove organic matter during heat treatment. This results in: 

• Longer manufacturing times,
• Additional energy costs,
• VOC emissions,
• The risk of damaging and/or contaminating the part.

In addition, printing an intimate blend of various materials with compositional gradients can often be complex. 
The use of many organic compounds can also prove problematic for the bond between the composition and the substrate or between successive layers.

The proposed solution is an additive manufacturing technology using colloidal assembly in a microfluidic device. 

For this purpose, 2 stable ceramic suspensions are injected coaxially or in a Y-shape. A careful selection of species allows particles to self-assemble on site in the microfluidic channel. In addition, feasibility has been demonstrated on the following systems: silica/modified silica, alumina/modified alumina, silica/alumina. Current part resolution is 300µm (dry part).

To adapt the part to its intended use, it is also possible to:

• Adjust the concentration, size of particles and the nature of the species in suspensions (final porosity, concentration gradient, core/shell structure).
• Modify the injection configuration and the number of injection systems, simultaneously or alternatively.
• Add components to one of the suspensions (composites).

This also permits the use of fluid solutions, free from organic compounds, therefore without debinding. This solution reduces pollution, energy costs and the risk of damaging the part. It is also easier to use, as it streamlines the formulation stage.

Thanks to the self-assembly of particles that interact with one another during the process, this solution makes it possible to print parts from an intimate blend of various materials with compositional gradients. In addition, the absence of binders ensures good adhesion between coats or with a substrate.