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 m2.g–1, and the room temperature permeability measurements indicated a wide range for k 1 (0.28 × 10–9–11.48 × 10–9 m2) and k 2 (0.34 × 10–5–54.17 × 10–5 m) according to the selected PU substrate. Hot air permeation tests showed that the foams were stable up to 700 °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.

Porous SiC ceramic is considered as a suitable material for hot gas filtration, microfiltration, and many others industrial applications. However, full utilizations of porous SiC ceramics have been limited by high‐processing costs. In this study, mullite‐bonded porous SiC ceramics membranes were prepared using commercial SiC powder, alumina, clay, and different sacrificial pore formers. The effect of different pore formers on the microstructure, mechanical strength, porosity and pore size distribution, air, and water permeability of porous SiC ceramics were investigated. The average pore diameter, porosities, and flexural strength of the final ceramics varied in the range 3.7‐6.5 µm, 38‐50 vol. %, and 28‐38 MPa, respectively, depending on the characteristics of pore former. The Darcian (k1) and non‐Darcian (k2) permeability evaluated from air permeation behavior at room temperature was found to vary from 1.48 × 10−13 to 4.64 × 10−13 m2 and 1.46 × 10−8 to 6.51 × 10−8 m, respectively. All membranes showed high oil rejection rate (89%‐93%) from feed wastewater with oil concentration of 1557 mg/L. The membrane with porosity ~48 vol% and mechanical strength 31.5 MPa showed and highest pure water permeability of 13 298 Lm−2h−1bar−1.

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