Hot air permeable preceramic polymer derived reticulated ceramic foams

Abstract

Open and partially closed cell polymer derived ceramic, specifically silicon oxycarbide, foams were produced from commercially available polyurethane (PU) foams through the replica technique combined with the preceramic polymer pyrolysis route. The focus was directed on the role of PU morphology (cell size and open/partially closed cells), synthesis parameters (cross-linking temperature and time), and type of the polysiloxane precursors for fine-tuning the microstructural features of the resulting ceramic foams and their eventual effect on the fluid dynamic/mechanical properties. Consequently, ceramic foams having dense/hollow struts with/without hierarchical porosity were able to be manufactured and characterized in detail. The average total porosity including all compositions was above 95%, the maximum surface area was found to be reaching 79 m(2).g(-1), and the room temperature permeability measurements indicated a wide range for k(1) (0.28 x 10(-9)-11.48 x 10(-9) m(2)) and k(2) (0.34 x 10(-5)-54.17 x 10(-5) m) according to the selected PU substrate. Hot air permeation tests showed that the foams were stable up to 700 degrees C without any loss of functionality. Accordingly, they are envisioned to be employed as reusable air filtration device parts for pollutants (viruses, bacteria, dust, etc.), catalytic supports, and filter components for reactions occurring in aggressive environments.