State-of-the-art high-temperature shielding materials are not flexible; however, a new technology forms the structurally robust, thermally stable boron nitride nanotube (BNNT) into a low-weight, flexible mat. BNNT advancements are highly sought after because they are as strong as carbon nanotubes but with a much higher resistance to heat, high voltage, and neutron radiation. The flexible BNNT mat can provide temperature protection up to 1300 °C with density of 200-400 kg/m 3.
Originally developed as a flexible thermal protection system (FTPS), this BNNT mat was designed to shield a 40-ton craft from the high aerothermal flux of atmospheric entry, descent, and landing. The novel, lightweight, flexible BNNT mat is an excellent flame-retardant material and has shown excellent thermal stability and shielding capabilities under a hypersonic thermal flux test in air.
The BNNT mat or fabric creates an in-situ passivation layer under high thermal flux, which minimizes penetration of the atmosphere (air or gas), as well as heat and radiation, through the thickness. BNNT effectively diffuses heat throughout the mat or fabric laterally and radially to minimize localized excessive heat. In addition, the BNNT mat can efficiently alleviate the heat via radiation because of its high thermal emissivity.
This invention offers a lightweight, simple, single-layer BNNT FTPS with better thermal protection and flame retardation performance in extreme environments while providing structural robustness. The BNNT materials can also serve as flame-retardant additives in composite systems that are also potentially more colorable compared to carbon nanotube additives.