By Josh Perry, Editor
Researchers from the University of California Los Angeles (UCLA), and eight other research institutions, created an ultra-lightweight, durable, ceramic aerogel that can withstand extreme temperatures and could be used as insulation for aerospace applications.
The new ceramic aerogel is so lightweight that it can rest on a flower without damaging it. (Xiangfeng Duan and Xiang Xu/UCLA)
According to a report from UCLA, ceramic aerogels have been in use for two decades, but this new version is far more durable, lighter, and more elastic than previous materials.
“When it’s heated, the material contracts rather than expanding like other ceramics do,” the article explained. “It also contracts perpendicularly to the direction that it’s compressed — imagine pressing a tennis ball on a table and having the center of the ball move inward rather than expanding out — the opposite of how most materials react when compressed.”
This unique property allows the material to be compressed to five percent of its original volume and still fully recover. This is four times better than previous aerogels, which could only recover when compressed to 20 percent of original volume.
The material is composed of boron nitride and the atoms are connected in hexagon patterns. This structure enabled it to withstand hundreds of exposures to sudden and extreme temperature changes, from -198°C to 900°C. Another test demonstrated the material retained 99 percent of its mechanical strength when stored for a week at 1,400°C.
“The aerogel’s ability to contract perpendicularly to the direction that it’s being compressed — like the tennis ball example — help it survive repeated and rapid temperature changes,” the article said. “It also has interior ‘walls’ that are reinforced with a double-pane structure, which cuts down the material’s weight while increasing its insulating abilities.”
Researchers believe the process for building this aerogel could be adapted to other insulating materials.
The research was recently published in Science. The summary read:
“Materials that operate in extreme environments, such as aerospace applications that require operation at high temperatures and in reactive atmospheres, must be ultralight, very mechanically strong, and thermally insulating. Achieving such disparate functionalities requires rational design not only of the material itself but also of hierarchical structures at multiple length scales that can respond in the desired way to extreme environmental factors in real time.
“On page 723 of this issue, Xu et al. (1) report the synthesis of a multifunctional structure with hyperbolic surfaces (saddle shapes with negative curvature) in the form of an aerogel where the solid medium is a network of atomically thin sheets of hexagonal boron nitride (hBN). By careful mechanical design of the microstructure, the authors report that their aerogels exhibit extraordinary mechanical and thermal resistance properties far superior to those of current aerogels.
“Their discovery opens new pathways for the integration of rationally designed ultralightweight materials with the correct combination of mechanical and thermal properties for a variety of extreme environments.”