Multi-scale design of a hypocrystalline ceramic nanofibrous airgel. a, Modes of deformation and corresponding ν and α of crystalline (C), amorphous (A) and hypocrystalline (H) ceramic fiber cells under mechanical and thermal excitations. The colored scale bar indicates the variation of the ceramic from amorphous to crystal using a local entropy-based fingerprint to characterize the crystallinity of each atom in the simulated system. b, Illustration of the design of the zig-zag architecture based on hypocrystalline fibrous ceramic. The units of the colored scale bars are millimeters, presenting absolute displacement values in the calculation of ν and α. Triangular, square and pentagonal cells are the building units to assemble the fibrous structure of the airgel. Credit: Nature (2022). DOI: 10.1038/s41586-022-04784-0
A team of researchers from Harbin Institute of Technology, China, together with an American colleague, have developed a new type of airgel for use in flexible thermal insulation material applications. In their article published in the journal Naturethe group describes how they made their airgel and how well it performed when extreme heat was applied.
Previous work has shown that aerogels made from ceramic materials work very well as thermal insulators – their very low densities have very low thermal conductivity. But these materials are brittle, which makes them unavailable for use in flexible material applications, such as firefighter suits. They also tend to decompose when exposed to very high temperatures. In this new effort, researchers have developed a method of making a ceramic-based airgel that can be used in flexible applications and also does not break down when exposed to very high temperatures.
To create their airgel, the researchers took a new approach – they pushed a zirconium-silicon precursor, using a plastic syringe, through a turbulent airflow chamber – an electrospinning approach that produced a ceramic material resembling cotton candy. They then bent the resulting material into a zigzag pattern and heated it to 1100°C. Heating it in this way changed the texture of the material from a glassy state to a nanocrystal. Studying the resulting material using a spectroscope showed that their approach resulted in the creation of a material with nanocrystalline pieces embedded in an amorphous zircon matrix – a flexible airgel made using a ceramic that was not susceptible to decomposition at high temperatures.
The researchers tested the material by using it to insulate an airplane fuel tube and applying a butane torch for five minutes. They found that using a generic polyimide barrier allowed temperatures in the tube to reach 267°C, while a conventional airgel kept the temperature at 159°C and the new gel kept it at just 33°C. C. They also found that the material was flexible enough to allow use in soft cloths, such as those used to make protective clothing for firefighters.
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Jingran Guo et al, Hypocrystalline ceramic aerogels for thermal insulation under extreme conditions, Nature (2022). DOI: 10.1038/s41586-022-04784-0
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Quote: A Ceramic Airgel Made with Nanocrystals and Embedded in a Matrix for Use in Thermal Insulation Applications (2022, July 1) Retrieved July 2, 2022 from https://phys.org/news/2022-07-ceramic -aerogel-nanocrystals-embedded-matrix.html
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