Adding functionality to powder bed fusion materials: Creating magnetic polymers using hybridized hollow carbon nanofibres

A method is presented, using Fe3O4 nanoparticles hybridized with hollow carbon nanofibers (Fe3O4NP@CNF) as an example, to add functionality to polymer powders for powder bed fusion with laser beam (PBF/LB-P). There are currently only a small number of polymers that can be processed successfully and reliably by PBF/LB-P. It was proposed that coating PA12 powder, a material that has a good track record in laser sintering, with a small amount (0.1 wt%) of Fe3O4@CNF would provide a new material with additional functionality without affecting the processability of the PA12 powder, since the Fe3O4 is contained within the CNF. Commercial PBF/LB-P PA12 particles were coated with Fe3O4@CNF without altering the morphology of the powder particles. No significant reduction in the PBF/LB-P processing window was observed when processing the resulting polymer nanocomposites, and parts were produced with comparable mechanical properties to the base polymer. Interestingly, magnetic investigations of PBF/LB-P cylinders built in three different orientations, with alignment of the long symmetry axis along the X, Y or Z axes of the build chamber, showed a preferential orientation of the hybridized magnetic fibers along the Z-axes in the composite. This suggests the appealing possibility of tailoring pieces with preferential magnetic orientation. Moreover, no agglomeration or nanoparticle growth was observed after PBF/LB-P. It is proposed that the low-cost method used in this work could be easily applied to other nanoparticles, without creating restrictive processing windows and the time-consuming process to determine them. Thus, a range of powders with additional functionality could be easily created for use in a variety of applications and industries.