Iron oxide is a soft magnetic material with relatively high saturation magnetization, low electrical conductivity, high permeability, and easy magnetization/demagnetization properties which make it a material of choice for applications such as the cores of inductive coils, drug delivery systems, and wastewater treatment.
A particular sub-branch of 3D printing is extrusion-based printing of metallic and ceramic colloidal materials, where highly concentrated suspensions of particles are deposited to construct near-net shaped parts with complex geometries.
Highly loaded suspensions that are to be used as inks for 3D printing can only be achieved through careful tailoring of additives that can cater the properties of each type of particle.
The level of loading that is attained in this work (∼81 wt% of iron oxise nanoparticles), eliminates the need for material removal steps and offers, for the first time in literature, a magnetic ink that contains the highest loadings of particles with a minimum amount of a single additive (1.15 wt%).
To demonstrate the printability of various geometries, the researchers printed three different shapes of magnetic cores (rectangular, thick-walled toroidal, and thin-walled toroidal) and a porous lattice structure.
They then The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive.
They point out that this fully aqueous system has the potential to pave the way for domestic printing of ceramics.
"The particle-specific approach that is described for iron oxide provides a solid route to expand the limited portfolio of 3D printing inks," the authors conclude.