A multidisciplinary team of physicists and chemists from the Institute of Physics of the Czech Academy of Sciences managed to create a graphene aerogel resistant to flames at a temperature of 1500 °C. A mere millimetre of the material is sufficient to shield such high temperatures. The new porous graphene aerogel temporarily resists various types of high-temperature flames, including an extremely reactive hydrogen flame.
By creating a special 3D porous structure, the researchers have succeeded in increasing the temperature resistance of graphene by an incredible 1,000 °C. Graphene, an atomically thin layer of carbon atoms, normally exhibits thermal stability in flames up to a temperature of 550 °C. This is approximately equivalent to the ignition temperature of the most used plastics today, which catch fire between 400 and 500 °C.
“In everyday life, we encounter different fire protective coatings and chemical treatments that can retard the combustion of materials but provide only temporary prevention because they do not alter their inherent properties. Very few materials can withstand such high temperatures in a fire. The developed graphene aerogel can do it. Moreover, it is very light, flexible, and has low thermal conductivity,” explains Jiří Červenka, the head of the scientific team from the Institute of Physics.
Strong as steel, flexible as fabric
The advantage of the new material is not only its low density (which is only 6 times higher than that of air), but also its high flexibility and strength. The aerogel is strong as steel. It can be compressed to more than 90% of its original size thanks to its unique porous cellular structure and covalently interconnected graphene layers.
“The material might be used, for example, as a top layer of a fire-resistant suit to protect a person from high-temperature flames while providing excellent thermal insulation,” explains Martin Šilhavík, the first author of the research.
The fire resistance of the graphene aerogel itself is based on the self-extinguishing mechanism, which causes the pores of the aerogel to be filled with carbon dioxide. The carbon dioxide in the aerogel prevents individual graphene planes from igniting. This principle is very similar to the mechanism which is used in carbon dioxide fire extinguishers. “A similar fire-retardant mechanism can also be used to improve the fire resistance of other materials,” says Martin Šilhavík.
The article was published in ACS Nano:
Martin Šilhavík, Prabhat Kumar, Zahid Ali Zafar, Robert Král, Petra Zemenová, Alexandra Falvey, Petr Jiříček, Jana Houdková, and Jiří Červenka, High-Temperature Fire Resistance and Self-Extinguishing Behavior of Cellular Graphene, ACS Nano 2022, https://doi.org/10.1021/acsnano.2c09076