Researchers have architecturally designed plate-nanolattices — nanometer-sized carbon structures — that are stronger than diamonds as a ratio of strength to density. The material consists of closely connected, closed-cell plates instead of the cylindrical trusses common in such structures over the past few decades. Previous beam-based designs have not been efficient in terms of mechanical properties. The new design has been shown to improve on the average performance of cylindrical beam-based architectures by up to 639% in strength and 522% in rigidity.
The material is fabricated through a 3D laser printing process called two-photon lithography direct laser writing. As an ultraviolet-light-sensitive resin is added layer by layer, the material becomes a solid polymer at points where two photons meet. The technique is able to render repeating cells that become plates with faces as thin as 160 nanometers.
The researchers included tiny holes in the plates that could be used to remove excess resin from the finished material. As a final step, the lattices go through pyrolysis, in which they’re heated to 900 °C in a vacuum for one hour. The end result is a cube-shaped lattice of glassy carbon that has the highest strength scientists ever thought possible for such a porous material.
Another goal of this work was to exploit the innate mechanical effects of the base substances. As a material’s size is dramatically decreased to 100 nanometers, it approaches a theoretical crystal with no pores or cracks. Reducing these flaws increases the system’s overall strength.