In the last three decades, considerable effort has been devoted to obtain both open and closed porosity ceramics & glasses in order to benefit from unique combination of properties such as mechanical strength, thermal and chemical stability at low‐relative density. Most of these investigations were directed to the production and the analysis of the properties for open porosity materials, and regrettably quite a few compositions and manufacturing methods were documented for closed porosity ceramics & glasses in the scientific literature so far. This review focuses on the processing strategies, the properties and the applications of closed porosity ceramics & glasses with total porosity higher than 25%. The ones below such level are intentionally left out and the paper is set out to demonstrate the porous components with deliberately generated closed pores/cells. The processing strategies are categorized into five different groups, namely sacrificial templating, high‐temperature bonding of hollow structures, casting, direct foaming, and emulsions. The principles underlying these methods are given, with particular emphasis on the critical issues that affect the pore characteristics, mechanical, thermal and electrical properties of the produced components.

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.

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In this study, we developed a microbolometer chip fabricated from high temperature superconducting Bi 2 Sr 2 CaCu 2 O 8?d (Bi2212) single crystals for the terahertz (THz) detection. For the manufacturing of the microbolometer chips, Bi2212 single crystals were transferred on substrate in the thin film like form and electron beam lithography, ion beam etching techniques were used. Resistance versus temperature behavior of the bolometer chips were performed by four probe technique in liquid nitrogen cryostat. Bi2212 microchips were integrated and characterized using in our custom-designed cryogenic bolometer system instead of expensive and massive cooling systems. The fabricated microchips significantly detected signals from the Stefan-Boltzmann lamp which includes a portion of THz radiation. The detected power and response time were studied for Bi2212 thin film like microbolometer chips. Our results demonstrated the feasibility of improved Bi2212 microchips could be used for bolometric detection for THz applications.

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