New materials that can withstand extremely light and sudden temperature changes are developed, can be used for insulation of spacecraft

by NASA-Imagery

The University of California Los Angeles (UCLA) and the research team of the eight research institutes reported that they succeeded in creating very lightweight and durable ceramic airgel . This material which can withstand extremely severe temperature change is expected to have possibility to be used for heat insulation materials of spacecraft.

Double-negative-index ceramic aerogels for thermal superinsulation | Science
http://science.sciencemag.org/content/363/6428/723

Researchers create ultra-lightweight ceramic material that with stands extreme temperatures
https://phys.org/news/2019-02-ultra-lightweight-ceramic-material-extreme-temperatures.html

Aerogels are porous substances produced by replacing solvents contained in gels with gas by supercritical drying . Even though 99% of the deposit is air, the airgel is solid, and it is strong if it is structurally very lightweight material. Airgel can be manufactured from many materials including carbon and metal oxides etc, among which ceramic aerogels are excellent in shielding extreme temperatures and are resistant to fire and corrosion , Ceramic airgel is said to be excellent as thermal insulation.

In fact ceramic airgel has been used as a heat insulator since the 1990s and it was also used as a thermal insulation material for scientific equipment installed in NASA's Mars probe. However, since conventional ceramic airgel is fragile, it is repeatedly exposed to extremely high temperatures or it is easily broken by sudden temperature change. Ultra high temperature and sudden temperature change are common phenomena in space exploration and it was impossible to make large use of ceramic airgel as insulation material such as spacecraft.

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The ceramic aerogels newly developed by research teams such as UCLA are extremely excellent in durability against repetition of extremely high temperature and very low temperature condition and ultra high temperature condition, and they have succeeded in considerable weight saving Thing. Moreover, it seems to be rich in elasticity due to unique atomic composition and fine structure.

The new ceramic airgel consists of a layer of ceramic with atoms bonded to a thin hexagonal pattern like boron nitride and wire mesh. It is said that the new material shrinks inward rather than expanding unlike other ceramic materials when it overheats. With this characteristic, the new material has higher flexibility and durability than the previous ceramic airgel. Even though conventional aerogels are crushed, it is only 20% of the original volume that can be restored, but the new material seems to be able to recover even if it is crushed to just 5% of the original volume.

In the experiment led by UCLA, it is said that the new material was endured even in situations where other aerogels are damaged. Even if the engineer repeated hundreds of times to change the temperature from -198 degrees to 900 degrees in just a few seconds, the new material did not break. Also, even if the ambient temperature was set at 1400 ° C and left for 1 week, the mechanical strength of the new material was only lost by less than 1%.

According to Xiangfeng Duan, a chemistry professor at UCLA, "The key to the durability of the new ceramic airgel we developed is a unique structure.The inherent flexibility of this structure is different from other It helps to withstand extremely high temperatures and severe temperature changes that will destroy the airgel. "

Also, Mr. Duan says that the process developed to make this new material can be applied to make other super light materials. "These ultra light materials can be used not only as insulation for spacecraft, automobiles, and other specialized equipment, but also for thermal energy storage, catalysts, filtration," Duan said .