Ultra-light ceramic aerogel stands up to intense temperature swings
Ceramic aerogels have been protecting industrial equipment and space-bound scientific instruments for decades, thanks to their incredible lightness and ability to withstand intense heat. The problem is they can be pretty brittle. Now, a team led by researchers at the University of California Los Angeles (UCLA) has developed a new ceramic aerogel that's far hardier and more flexible, even after repeated exposure to wild temperature swings.
Aerogels are strong, solid structures that are up to 99 percent air by volume, which of course makes them incredibly lightweight. They can be made of many different types of materials, but ceramics are particularly handy as thermal insulators. On the flipside though, extended cycles of heating and cooling can end up fracturing the material.
In this case, the researchers made their aerogel out of thin layers of the ceramic material boron nitride, with its atoms arranged in a hexagonal pattern. To test out how well it performed, the team put samples of the stuff in a chamber and fluctuated the temperature between -198° C and 900° C (-324° F and 1,652° F), with just a few seconds between each extreme. The material was also left in a chamber heated to 1,400° C (2,552° F) for a week. Altogether it was found to lose only one percent of its mechanical strength.
According to the team, the key to the ceramic aerogel's strength is its unique architecture. Unlike most ceramics which expand when heated, the aerogel contracts instead, and it does so in a strange way. If you imagine pressing down on the top of a tennis ball, the sides would bulge outwards – but squeezing this aerogel, the sides would also push themselves inwards. The stuff can fully bounce back after being compressed to just five percent of its original volume, while other aerogels can't go any lower than 20 percent.
The team says that this aerogel, as well as others made using the same process, could lead to a new class of ultra-strong, ultra-light materials.
"Those materials could be useful for thermal insulation in spacecraft, automobiles or other specialized equipment," says Xiangfeng Duan lead researcher on the project. "They could also be useful for thermal energy storage, catalysis or filtration."
The research was published in the journal Science.