Aerospace composites: Propelling aviation engineering
By Jeremy Cook
New and enhanced materials are revolutionizing the world of aerospace engineering. In this article, we’ll explore some of the new composite materials that allow us to reach Mars and beyond.
Aerospace composites: Carbon fiber, nanotubes, and graphene
Carbon fiber was first constructed in the 1800s for use in lightbulb filaments, using materials like bamboo and cotton. It wasn’t until the mid-twentieth century that researchers explored this material as a potential structural element.
Today, most carbon fiber is made from polyacrylonitrile. These tiny individual fibers are bound together with the help of a plastic binder to form an extremely strong and lightweight material. The weight savings realized from carbon fiber materials mean reduced fuel consumption for rockets reaching space, airplanes in flight, and even your next bike ride.
We can consider other aerospace composites, carbon nanotubes, graphene, and buckminsterfullerene, to be the next evolution in carbon material technology. Each of these materials consists only of carbon atoms bonded with three of their atomic neighbors.
- Carbon nanotubes: carbon atoms wrapped into molecular tubes that are akin to extremely small wires—or even hairballs—when combined, forming an extremely strong material.
- Graphene: carbon atoms bound together and arranged in sheets (not wrapped into tubes). Graphene is the strongest material ever tested, with several interesting properties that may make it appropriate for energy storage.
- Buckminsterfullerene: carbon atoms wrapped in a ball (60 carbon atoms, or C60). While perhaps less explored for aerospace uses than the other carbon-based molecules listed here, researchers may find important uses for it in the future.
Aerogel for aerospace and defense
Samuel Stephens Kistler created aerogel in 1931 by removing liquid from a jelly. The resulting solid substance is largely air. Modern aerogel is often formed from silicon, removing liquid molecules to create an extremely porous substance that can be over 99% air by volume.
Because of its construction as “stationary” air, aerogel is a fantastic insulator. Thermal conductivity can be less than the gas it contains, thanks to aerogel’s high porosity and the Knudsen Effect, which restricts molecular movement and, thus, thermal energy transfer. This porosity also makes aerogel hydrophilic and able to absorb a large amount of moisture. However, additives can make it water-resistant.
These properties make aerogel a fantastic material with a wide range of potential applications, including by NASA. In its raw form, it can be quite brittle and is undoubtedly on the exotic side, but it’s been used for more terrestrial applications where extreme insulation within minimal volume is required.
Metal 3D printing, advanced heat treatment, aerospace composites, and beyond
Throughout history, advances in metalworking have driven society forward. While not a new material per se, the ability to 3D-print metals allows us to form shapes that would have been impossible before. Consider that 3D printing is used extensively in the construction of rockets.
Ancillary to 3D printing, the way metals are heated and cooled to enhance their properties will no doubt continue to be used in space and aviation engineering. We can expect to see a wide range of new aerospace parts made with metal, silicon, and carbon powering us into the future.
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