Phys.org February 15, 2023
Boron nitride nanotubes (BNNTs), structural analogues to carbon nanotubes, are a strong candidate for nanofillers in high-temperature composites due to their high thermal stability, oxidation resistance, excellent mechanical properties, and high thermal conductivity. A team of researchers in the US (FAMU-FSU College of Engineering, industry) tested samples of high-quality, high-purity BNNTs in an inert atmosphere for thermal failure up to 2500 °C. A significant fraction of the BNNTs survived temperatures as high as 2200°, and the BNNT samples were completely undamaged at temperatures as high as 1800 °C. Boron nitride (BN) nanopowders were tested identically to perform a comparative study, as hexagonal BN is commonly found in purified BNNT samples. They attributed color darkening, significant weight loss, an increased boron atomic level, significant weight gain upon oxidation, to the presence of boron oxide compounds in an oxidized sample, and the observed boron clusters at the nanoscale to dissociation of B-N bonds in the BNNT sample at 2200 °C. They observed the stability of BNNT structures up to 2000 °C, with local/partial wall dissociation or unzipping, and complete survivability of highly crystalline BNNTs was demonstrated up to 1800 °C… read more. TECHNICAL ARTICLEÂ
Graphical abstract. Credit: ACS Appl. Nano Mater. 2022, 5, 9, 12444–12453, August 25, 2022Â