While residential fires have declined over the recent decades, the uncontrollable blazes can still wreak havoc, as the recent fire in a Bronx apartment building demonstrated. Many fire-resistant materials have hit the market, but not all of them have proven effective, and some of them are even harmful to human health. A new study out of the University of Queensland, Springfield in Australia, in collaboration with the College of Chemistry and Materials Engineering in China, demonstrates a new type of material to stop a fire in its tracks.
Published in Matter during the first week of January, the researchers, led by Pingan Song, took inspiration from another fiery source for their new coating: lava. Volcanic lava cools quickly but takes longer to solidify the more it cools. This is because molten lava forms a crust called a “char” that insulates the lava below it, and the outer coating prevents fire from reaching it.
Molten lava is mainly composed of silicon and oxygen, creating a liquid with low thermal conductivity and is entirely fireproof, two properties that the researchers attempted to emulate. The team’s fire-retardant material comprises of metal oxides, boron nitride, and a fire-retardant polymer they created back in 2021. When the metal oxides reach 350 °C, they begin to melt; this is advantageous because fire can reach 600 °C and higher temperatures. The metal oxides form a crust, and then the boron nitride fills the cracks. The resulting crust was akin to a ceramic coating. The polymer is the glue between the coating and the material it protects, creating a strong, adhesive fire-resistant layer.
The mix can be dissolved in water to form an aerosolized spray that can coat a host of materials, including foam insulation, wood, and steel. To test the efficacy of the coating, researchers sprayed it onto each of the materials. After letting it cool, they exposed the material to flame from a butane torch, burning at 1100 °C for 30 seconds.
The authors report that the coating exhibited “rapid, self-extinguishing behavior” to protect the material beneath. The fire also caused the coating to expel carbon dioxide, a non-flammable gas, protecting from further flames. Notably, the coating also protected wood and steel, two substances found in buildings susceptible to fire damage.
The research is promising, with the novel coating proving more effective than traditional fire-retardant coatings. The cost of the compounds, most of them precursors to ceramics, are inexpensive and readily available, and the compound is easily applied to a variety of surfaces.
While researchers hope to make their product readily available as soon as possible, the design is still in its early stages.