Diamonds are among the hardest materials on Earth thanks to how the carbon atoms arrange themselves. Now researchers have worked out a way to make an even stronger carbon nanostructure.
As reported in Nature Communications, the team from the University of California, Irvine, and other institutions successfully designed a lattice nanostructure with repeating units organized in a grid. Previous designs have focused on cylindrical beams to construct similar nanostructures. This one uses closely connected, closed-cell plates that outperform beam-based lattices in both average strength and stiffness, 6.39 times and 5.22 times respectively.
"Scientists have predicted that nanolattices arranged in a plate-based design would be incredibly strong," lead author Cameron Crook, a UCI graduate student in materials science & engineering, said in a statement. "But the difficulty in manufacturing structures this way meant that the theory was never proven, until we succeeded in doing it."
Creating such a structure was only possible with a sophisticated 3D laser printing process called two-photon lithography direct laser writing. They started with an ultraviolet-light-sensitive liquid resin and then hit it with a laser. Where two photons met, the polymer became a solid. In this way, by moving the laser around in three dimensions, they were able to create an assembly of regular plates, each as thin as 160 nanometers.
The team's approach is innovative because they designed the structure with holes so that excess resin could be drained from the material. The final step was to bake the material at 900°C (1,652°F) to produce a glassy carbon lattice with incredible strength, especially for a porous material.
"As you take any piece of material and dramatically decrease its size down to 100 nanometers, it approaches a theoretical crystal with no pores or cracks. Reducing these flaws increases the system's overall strength," said Jens Bauer, a UCI researcher in mechanical & aerospace engineering.
The team were the first to make this happen and prove the material holds up to par with predictions. In the future, it's possible nanostructures such as these could be used in the aerospace industry due to their strength to weight ratio.