It’s no secret that advancements in technology are often followed by advancements in military technology; even the very concept of space exploration was propelled by a desire to outperform a competing world power. It’s no surprise, then, that even in today’s relatively peaceful time we see developments in the world of combat technology: projectiles, vehicles, and in this case from a study published in Nature Materials, armor.
Materials scientists from the Massachusetts Institute of Technology (MIT) recently developed a new type or possible armor material, composed of tiny carbon nanostructures that resemble very small struts. The researchers did so by exposing a photosensitive polymer resin to lasers, in such a way that the resulting lattice resembles microscopic struts. The entire setup is then treated in a high-temperature vacuum chamber, converting the resin into an ultralight carbon structure. The structure is said to resemble functional geometry in “energy-mitigating foams,” according to lead author Carlos Portela, lending the material its impact-absorbing property. According to Portela, the resulting structure “gives rise to a rubbery, bending-dominated architecture,” despite carbon’s tendency to form brittle structures, as is perhaps most evident in graphitic carbon inside pencils the world over.
The carbon struts can be rearranged by tweaking its inner architecture, consequently changing the properties of the overall resulting material. The impact-absorbing properties of the new material, however, were determined by bombarding it with high-kinetic energy particles ejected from a gold film-coated glass substrate with silicon oxide particles, which were then bombarded with lasers to form a rapidly-expanding plasma that sends the particles towards the target material. Adjusting the power of the laser allows the researchers to vary the projectile speeds of the particles hitting the target, which range from 40 to 1,100 meters per second (89 to 2,460 miles per hour), well within supersonic speeds. Through continuous testing using this method, the researchers were able to tweak the strut design, leading to the design finally reported in the study.
In the final design, the particles that hit the material ended up being embedded in it—much like how Kevlar absorbs projectiles in real-world applications—instead of tearing right through, much like how they are expected to go through sheet metal. The researchers believe that this is a result of the carbon struts absorbing much of the impact energy from the particle projectiles through its “shock compaction mechanism” resulting from the strut arrangement. And with a material thickness thinner than the width of a strand of human hair, the new material is said to be more efficient at impact absorption than even steel or Kevlar at a comparable weight. Upscaling the process could, therefore, pave the way for even better impact-absorbing armor.
According to co-author Julia Greer, the study paves the way for “ultra-lightweight impact resistant materials [for use in] efficient armor materials, protective coatings, and blast-resistant shields desirable in defense and space applications.”
Bibliography
- Lavars, N. (2021, June 24). Ultralight armor material made of tiny carbon struts outperforms Kevlar. New Atlas. Retrieved August 31, 2021, from https://newatlas.com/materials/ultralight-armor-material-struts-carbon-kevlar/
- Portela, C. M., Edwards, B. W., Veysset, D., Sun, Y., Nelson, K. A., Kochmann, D. M., & Greer, J. R. (2021). Supersonic impact resilience of nanoarchitected carbon. Nature Materials, 1–7. https://doi.org/10.1038/s41563-021-01033-z
