Effect of layer height on the remanence of 3D printed strontium-ferrite PA12 magnetic composites.

We are investigating magnetic composites to better understand how additive manufacturing can be used to design lightweight, low-cost magnetic materials for use in electronics, sensors, and spintronic devices. A ROVA3D FDM printer of the Object Replication and Design Inc. was used to 3D print single-layer samples of 35 wt% strontium ferrite oxide (SFO) / polyamide 12 composite. Samples were printed with a layer height of 0.1 through 0.5 mm at extrusion temperatures of 190 °C and 200 °C using an 0.5 mm nozzle. A freely extruded filament with a diameter of 0.9 mm was also printed for comparison. The specimens were weighed using a Cahn C-30 microbalance. Magnetic hysteresis curves were measured with a MicroSense EZ9 vibrating sample magnetometer (VSM) along the sample's principal axes. From the hysteresis loops, S-values (Mr/Ms) were determined, which are largest perpendicular to the filament's axis, indicating flow-induced magnetic anisotropy. The S-value increases with smaller layer height, particularly parallel to the print bed normal. These results indicate that both print thickness and extrusion settings influence the magnetic anisotropy of SFO/PA12 composites.