Figure 1
Rheology of platelet pastes and platelet alignment during extrusion. (a) SEM image of a single alumina platelet. Scale bar 2 μm. (b) Dynamic mechanical analysis of the platelet laden printing paste, showing the paste stiffness and yield stress. (c,d,e) SEM images of filaments printed using different nozzle lengths, showing the effect of nozzle length on the level of concentric platelet alignment. Scale bars 30 μm. (f) Measured relative core radius plotted against the nozzle radius, demonstrating invariance. (g) Measured core radius plotted against nozzle length, showing an exponential relationship. (h) Velocity profile, V(r), and velocity gradient, dV(r)/d(r) across a 0.41mm nozzle, computed using Equations 2 and 3. The experimentally measured core diameters are marked after the paste is subject to the velocity gradient for three amounts of time, corresponding to the three lengths of printing nozzles (1mm nozzle: 0.1 s, 12.5 mm nozzle: 1.25 s, 25 mm nozzle: 2.5 s).
