3D-Printed lightweight ceramics using capillary suspensions with incorporated nanoparticles

Abstract

Additional image material, g-codes for 3D-printing and numerical data are shown, further a short discussion on smart capillary suspensions in contrast to capillary nanosuspensions is presented. G-codes are available as separated files. 1 Supplementary images and graphs Figure S1: (a) Bright-field TEM micrograph and (b-d) TEM-EDXS mappings of sintered capillary suspension using paraffin oil as bulk phase. "# = 15 % alumina particles (*+,-= 5.5 µm) and /0" = 3 % aqueous sucrose solution (30 vol%) as secondary phase. The sample was sintered at 1350 °C for 2 h. Dark areas represent vacuum regions. Grey areas represent carbon areas. which are present due to TEM sample preparation. Si areas are represented yellow and Al areas in blue. (b) Showing all three mapped elements, (c) presenting only the Al fraction and (d) shows only Si fractions. The presented images were not processed with the salt-and-pepper median filter.

Direct ink writing of hierarchical porous ultra‐high temperature ceramics (ZrB2)

“…12,13,24 Instead, the pores observed (Figure 2B,C) are primarily interconnected and open, and have random or disorganized shape from a few microns to about 20 μm in size. This microstructure is consistent with that produced from partial sintering of capillary suspensions [14][15][16][17] although the amount of oil in our formulations is greater than that typically used in capillary suspensions. In hindsight, it is not surprising since the transition between particle-stabilized emulsions and capillary suspensions has been observed as reported previously.…”

“…In addition, DIW paste inks were prepared from alumina capillary suspensions consisting of a bulk phase of liquid paraffin, mineral spirits, and palm wax 14,15 to create multi-scale porous honeycomb structures. 16 More recently, Weiß et al 17 included nanoparticles in the formulation to strengthen the bond between individual micron-sized particles without sacrificing porosity. Overall porosities of 88% were achieved and the structures have similar compressive strength to beams formulated by other methods, 15 while reducing the bulk density by a factor of 2-3.…”

“…Initially, we targeted particle-stabilized emulsion pastes, although we now believe that the paste inks are more likely to be capillary suspensions. [14][15][16][17] The schematic in Figure 1 illustrates the main difference between a particle-stabilized emulsion and capillary suspension. In the particle-stabilized emulsions, droplets of the oil phase are surrounded by particles rendered weakly hydrophobic by the addition of a surfactant, whereas the capillary suspensions display interpenetrating networks of the oil and water phase creating pendular and funicular bridges between the particles.…”

Ultrastrong Hierarchical Porous Materials via Colloidal Assembly and Oxidation of Metal Particles

“…A,B) Compressive strength of the hierarchical foam materials prepared in this work in comparison to A) conventional Al foams and Al 2 O 3 foams prepared with Al 2 O 3 particles [ 48,49 ] and B) bulk alumina foams prepared via various other methods, [ 6 ] including 3D printing. [ 19,20,23,50,51 ] C) Simulation of the stress distribution within a model hierarchical foam structure compared to a structure with dense walls at equivalent overall porosity and subjected to the same external stress. D) Stress distribution along the side edge of the structures (indicated in the inset) for different elapsed times and applied stresses.…”

“…To understand the dependence of the mechanical properties on the relative density of the hierarchical foams, we display the measured strength data in a double‐logarithmic plot together with results reported in the literature for porous ceramics prepared using other processing techniques (Figure 3B). [ 6,19,20,23,50,51 ] Theoretical predictions for model open‐cell and closed‐cell brittle materials are also included for comparison. [ 52 ] The compressive strength of brittle foams (σ) is often described by the simple scaling law: , where σ s is the fracture strength of the solid phase, ρ r is the relative density of the foam, a is the power law exponent and C is a constant.…”