A fundamental understanding of the thermal behavior of reinforcing materials is crucial to fully exploit their properties in composites. Boron nitride nanotubes, or BNNTs, are stronger and more resistant to high temperatures than carbon nanotubes. Like their carbon cousins, they are structures measured down to the nanometer — a length equal to one billionth of a meter.

In a new study, a team of FAMU-FSU College of Engineering researchers from the High-Performance Materials Institute examined the thermal limits of advanced nanomaterials. This is the first-ever study on how purified boron nitride nanotubes remain stable at extreme temperatures in inert environments.

The scientists found that BNNTs are completely stable in an inert environment, or the chemically inactive atmosphere in which they are produced, at temperatures up to 1800°C. In addition, they found that BNNTs can withstand brief exposure to temperatures of 2200 °C without losing the mechanical properties that make them so powerful.

Assistant Professor of Industrial and Manufacturing Engineering Rebekah Sweat said: “This research is about uncovering a trait that is incredibly useful for the future. We have a more robust understanding of how BNNTs perform when and how they thermally fail, because all materials have their limitations. We have changed the way we make these composites to better exploit their properties.”

“The possible applications of these light, strong composite materials are countless. Anything that gets hot, such as a turbine or motor, can use them to function in a high-temperature environment. They are thermally conductive, meaning they dissipate heat quickly, and their mechanical stability provides structural reinforcement.”

Lead author and PhD candidate Mehul Tank said: “Understanding the behavior of these nanotubes at high temperatures is crucial for making materials that can withstand extreme conditions, both in production and in final use. As we better understand how they function in these conditions, we can develop better fabrication of composites that utilize high-temperature processing matrices, such as ceramics and metals.”

Magazine reference:

  1. Mehul J. Tank et al, Extreme thermal stability and dissociation mechanisms of purified boron nitride nanotubes: implications for nanocomposites at high temperatures, ACS Applied Nano Materials (2022). DOI: 10.1021/acsanm.2c01965