A team at the FAMU-FSU College of Engineering, the joint school of Florida A&M University and Florida State University, is exploring the thermal limits of advanced nanomaterials — work, which was published in Applied Nano Materials, that could be a boon to medicine delivery systems, electronics, space travel, and more sectors.
Boron nitride nanotubes (BNNTs) are stronger and more resistant to high temperatures than carbon nanotubes, and they’re measured by the nanometer — a length equal to one-billionth of a meter. However, manufacturing these materials is challenging.
The team found that BNNTs are fully stable up to 1800 °C in an inert environment, the chemically inactive atmosphere in which they are manufactured. Also, BNNTs can withstand temperatures of 2200 °C for short periods without losing the mechanical properties that make them so effective.
“This research is about uncovering a property that is incredibly useful for the future,” said assistant professor Rebekah Sweat. “We have a more robust knowledge of how BNNTs perform — when and how they thermally fail — because all materials do have limitations. We have changed how we make these types of composites to better utilize their properties.”
Anything that gets hot — e.g., a turbine or engine — would benefit from BNNTs while functioning in a high-temperature environment; they’re thermally conducting, and their mechanical stability offers structural reinforcement.
In addition, BNNTs are thought to be perfect for space exploration — their ability to conduct heat, insulate electrical current, and block radiation could be used in space or a spacecraft during re-entry to Earth’s atmosphere.
“Understanding the behavior of these nanotubes at high temperatures is crucial for creating materials that can withstand extreme conditions, both in manufacturing and in their final use,” said Lead Author Mehul Tank. “As we understand better how they function in these conditions, we’ll be able to develop better manufacturing of composites that employ high-temperature processing matrices, like ceramics and metals.”
Here is a Tech Briefs interview with Sweat, edited for length and clarity.
Tech Briefs: What inspired your research?
Sweat: The inspiration came from needing to know the ultimate temperature of BNNTs in non-oxygen environments so we would not damage the materials while manufacturing new high-temperature components. There was no information, only theory, on the maximum temperature or how they fail under thermal conditions. I knew we needed to discover the thermal limits not only for scientific discovery but because we needed it to move forward in manufacturing ceramic and other composite components.
Tech Briefs: What were the biggest technical challenges you faced?
Sweat: The biggest technical challenge was identifying the mechanism by which nanotube walls break down. Checking to see if the structure is still stable is done inside a transmission electron microscope to look at the wall structure, which is tedious and time-consuming. It is challenging to find what is happening once you take the material out of the temperature to perform these tests and make the connection between minor changes in material breakdowns.
Tech Briefs: Can you explain in simple terms how the technology works?
Sweat: The technology discovery was how a novel nanomaterial (BNNT) fails in scorching temperatures. This information is used to determine the heating cycles to make parts like turbine blades. It is similar to cooking food; you need a precise baking recipe for a cake to turn out well. Similarly, we need exact recipes for making high-temperature parts to come out of the manufacturing furnace with good quality but much hotter than your oven at home.
Tech Briefs: What’s the inevitable next step? Any plans for future research/testing?
Sweat: The next step is exploring new ways and material possibilities to combine with BNNTs to get multifunctional and attractive properties, such as thermal conductivity, heat shielding ability, and toughness.
Tech Briefs: How long before we see your work applied to applications that need to function in high-temperature environments?
Sweat: It could be applied today based on our findings! In the broader sense, the general adoption of these novel materials could take 5-10 years, depending on market readiness.
Tech Briefs: Do you have any advice for engineers aiming to bring their ideas to fruition/market?
Sweat: Persistence through the challenges of studying new things is a must. Do not be afraid to work in an area where there is not a lot of information, and you can make progress faster with a collaborative team that has a wide range of backgrounds.
Tech Briefs: Anything else you’d like to add?
Sweat: The future of materials discovery is bright! Especially in extreme conditions, we can advance hypersonic flight, deep space travel, and even change how medicine is delivered to the body because the materials enable us to go further and push the limits of what is possible.