Processing of porous silicon oxycarbide ceramics from extruded blends of polysiloxane and polymer microbead

Abstract

Porous silicon oxycarbide (SiOC) ceramics with porosities ranging from 27% to 88% and a cell density higher than 107 cells/cm3 were made from polysiloxane and polymer microbead blends. The polysiloxane and polymer microbeads were compounded directly using a counter-rotated twin-screw extruder with a filamentary die. The obtained specimens were then transformed into porous SiOC ceramics using two different processes: (1) pyrolysis of the extruded blends and (2) foaming of the blends with gaseous carbon dioxide and subsequent pyrolysis. The pyrolysis process resulted in the production of closed-cell SiOC ceramics, while the combined foaming-pyrolysis process resulted in open-cell SiOC ceramics.