Combining robocasting and alkali-induced starch gelatinization technique for fabricating hierarchical porous SiC structures

Abstract

Hierarchical porous silicon carbide (SiC) structures with total porosity in a wide range of 37.82 %− 94.34 % were achieved by combining robocasting and alkali-induced starch gelatinization technique. (i) 50 µm-2 mm sized pores, with porosities of 22.33 %− 82.13 %, were created by robocasting. (ii) 1–140 µm pores, with porosities of 20.20 %− 68.21 %, were induced by the starch template. Additionally, we firstly introduced an alkali-induced starch gelatinization technique to the gel inks for robocasting, which promoted its elastic properties (storage modulus and shear yield stress) and prolonged its preservation time to 3–7 days. The gelatinized starch granules were also used as binder, which facilitated high-velocity (3–20 mm/s) extrusion of the inks through fine (150–800 µm) nozzles. The porous SiC structures with two scales of porosity are promising for wide applications such as porous burners, liquid and gas filters, catalyst supports and so on.