Boosting boron nitride’s high-temperature performance

Boron nitride is stable up to about 900 degrees Celsius and exhibits excellent thermal conductivity, making it a useful material for dissipating heat in electronics, batteries, and other high-temperature applications. But to apply this material in more extreme environments, researchers must improve its performance at even higher temperatures.

Using atomic layer deposition to coat boron nitride nanotube (BNNT) fabrics with aluminum oxide, Davis et al. enhanced the thermal conductivity and oxidation resistance of this material.

The atomic layer deposition technique resulted in uniform, conformal coatings on the interior surfaces of the BNNT fabrics. Measurements of the coated fabrics showed that the in-plane thermal conductivity increased by 15% compared to uncoated fabrics, and the through-plane thermal conductivity increased by 192%. When exposed to oxygen at 1000 degrees Celsius, the coated fabrics were 44 times more resistant to oxidation and their dimensions remained unchanged.

This method extended the high-temperature stability of BNNT fabrics past 900 degrees Celsius and has the potential to do the same for other nanoporous materials.

“Our work pushes the limits of high-temperature thermal management materials with a dual-purpose coating technique that mitigates contact resistance between nanotubes and simultaneously provides an environmental barrier,” said author Cole Davis.

Next, the authors will optimize the atomic layer deposition process using various techniques. This includes investigating coating thickness, other coating materials, and layering coatings of different materials.

“Other atomic layer deposition coating materials like silicon dioxide should also be explored for their oxidation protection and ability to stabilize the composite in the event of oxidation,” Davis said.

Source: “Dual-purpose alumina ALD coatings for enhanced oxidation resistance and thermal conductivity of boron nitride nanotube fabrics,” by Cole R. Davis, Sara C. Mills, Benjamin L. Greenberg, Aalok Gaitonde, Austin J. Cendejas, Kevin P. Anderson, Boris N. Feigelson, James A. Wollmershauser, and Amy M. Marconnet, Journal of Vacuum Science & Technology A (2025). The article can be accessed at https://doi.org/10.1116/6.0004912 .