A team of Northwestern researchers has created a new way to print three-dimensional metallic objects using rust and metal powders.

While current methods rely on vast metal powder beds and expensive lasers or electron beams, Northwestern’s new technique uses liquid inks and common furnaces, resulting in a cheaper, faster, and more uniform process.

The Northwestern team also demonstrated that the new method works for an extensive variety of metals, metal mixtures, alloys, and metal oxides and compounds.

Northwestern Engineering’s new 3D-printing process bypasses the conventional powder bed and energy beam approach, as well as uncouples the two-step process of printing the structure and fusing its layers.

By creating a liquid ink made of metal or mixed metal powders, solvents, and an elastomer binder, the researchers can rapidly print densely packed powder structures using a simple syringe-extrusion process, in which ink dispenses through a nozzle, at room temperature.

Despite starting with a liquid ink, the extruded material instantaneously solidifies and fuses with previously extruded material, enabling very large objects to be quickly created and immediately handled.

The researchers’ unique 3-D inks and process could be used to create more sophisticated and uniform architectures that are faster to create and easier to scale up. After the object is printed but before it is densified by heating, the structure, called a “green body,” is flexible due to the elastic polymer binder containing unbonded metallic powders.

The new method could be used for printing batteries, solid-oxide fuel cells, medical implants, and mechanical parts for larger structures, such as rockets and airplanes.

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