3D printed composites with uniform distribution of Fe3O4 nanoparticles and magnetic shape anisotropy

Abstract

A novel approach to fabricate magnetic elements made from nanocomposite materials by material extrusion is proposed. Flexibility in the shape and dimensions of this technology leads to the possibility to overcome the restrictions in the design and manufacturing of complex-shaped bulk magnets. The nanocomposites discussed here were fabricated by the addition of magnetite (Fe3O4) nanoparticles into a polymeric matrix: PEG-PVB and silicone gel. Composites with nanoparticles to polymer blend weight concentrations varying from 20% to 60% were prepared. The rheological behaviour of the suspensions was studied using rotational rheometry. The 3D prints were performed with and without an externally applied magnetic field. Microstructure, morphology and magnetic properties of the synthesised nanocomposites were confirmed by Fourier-transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), respectively. The composites showed a uniform morphology with nanoparticles embedded homogeneously in the matrix. Magnetic response, namely remanence, saturation, coercive field and squareness, depend substantially on the type of polymeric matrix and nanoparticles concentration. Composites based on silicone have around 20–25% lower squareness ratio than the PEG-PVB-Fe3O4 ones. The elements printed from selected composites exhibit weak but well pronounced magnetic shape anisotropy – a feature characteristic for bulk magnets.