Microarchitecture: Lightweight Construction Materials of Highest Stability

Lightweight construction materials modeled on nature; high stability at low density; ceramic microstructures produced by 3-D laser writing

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The framework construction made of a ceramic-polymer composite is highly stable, although the individual elements have a thickness of a few hundred nanometers only.
Credit: Picture: J. Bauer/KIT

Researchers at Karlsruhe Institute of Technology (KIT) have developed microstructured lightweight construction materials that show extremely high stability. The density of this material is said to be below that of water, yet their stability relative to weight exceeds that of heavier materials like high-performance steel or aluminum.

These lightweight construction materials feature a framework structure similar to  the shell structure of the bees’ honeycombs. The results of this research are now presented in the journal PNAS, DOI: 10.1073/pnas.1315147111.

This discovery may have a telling impact on new materials for the construction industry.

“The novel lightweight construction materials resemble the framework structure of a half-timbered house with horizontal, vertical, and diagonal struts,” said Jens Bauer, KIT, adding these beams are only 10 µm in size.

In total, the lightweight construction elements are about 50 µm long, wide, and high.

“Nature also uses open-pore, non-massive structures for carrying loads,” said Oliver Kraft, KIT. Examples he uses are wood and bones. At the same density, however, the novel material produced in the laboratory can carry a much higher load.

Imagine the impact on construction job expenses with lightweight structural components.

According to the press announcement, a very high stability was reached by a shell structure similar to the structure of honeycombs. It failed at a pressure of 28 kg/mm2 only and had a density of 810 kg/m3. This exceeds the stability / density ratio of bones, massive steel, or aluminum. The shell structure produced resembles a honeycomb with slightly curved walls to prevent buckling.

To produce these lightweight construction materials, 3D laser lithography was applied. The effect of laser beams hardens the desired microstructure in a photoresist.

The structure is then coated with a ceramic material by gas deposition. The structures produced were subjected to compression via a die to test their stability.

Source: AAAS EurekAlert