Successfully manufactured ultra-lightweight insulation material.
Scientists have successfully created a new type of insulation that is virtually weightless and has higher thermal resistance than most other materials.
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Experiments have shown the new material to have very high thermal insulation properties. Photo: X. Xu Et Al/Science 2019. |
The new material has an aerogel structure (at least 99 percent empty space), made from a type of ultrathin atomic ceramic (hexagonal boron nitride). This design demonstrates extremely high thermal stability and very rapid temperature changes in the range of over 1,000 degrees Celsius, scientists report in the journal Science on February 15.
“It’s very difficult to create materials that are both lightweight and highly heat-resistant,” said Deep Jariwala, an engineer at the University of Pennsylvania and co-author of a review of the same research in the journal Science. The new ultralightweight insulator has great potential for coating spacecraft components, as they must withstand very high temperature variations when flying past the sun or re-entering Earth’s atmosphere, he said.
The aerogel structure consists of a network of tiny air bubbles, each separated by two hexagonal layers of nitrified boron atoms (a trivalent metalloid). Similar to how double-glazed windows prevent heat from escaping a house in winter, this double-layered ceramic barrier makes it difficult for heat to transfer from one air bubble to another. “It’s very difficult for heat to transfer through the material by spreading along the layers of boron atoms, due to the long and winding path,” according to Xiangfeng Duan, a chemist and materials scientist at the University of California, Los Angeles.
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| Experiments have shown the new material to have very high thermal insulation properties. Photo: X. Xu Et Al/Science 2019. |
Researchers placed a fresh flower on a 2 cm thick piece of the new material and put it under a flame (the image on the right is a heat map). After 15 minutes, the top surface measured 45 degrees Celsius, and the flower was only slightly wilted.
While other aerogel ceramics may fracture under rapid temperature variations or prolonged thermal stress, the new aerogel material withstands up to 500 cycles of rapid heating and cooling from 198°C to 900°C (increasing or decreasing by 275°C per second), as well as remaining stable (retaining 95% of its flexibility) at 1400°C for a week.
According to Julia Greer, a materials scientist at the California Institute of Technology, the new material is still soft and flexible, so for practical applications it will probably need to be encased in a more durable material.
