Supermaterial with the weight and density of aerogel but 10,000 times the stiffness and enabling super solar sails in the 2030-2040 timeframe

Engineers at MIT and Lawrence Livermore National Laboratory (LLNL) have devised a way to translate that airy, yet remarkably strong, structure down to the microscale — designing a system that could be fabricated from a variety of materials, such as metals or polymers, and that may set new records for stiffness for a given weight.

The design is based on the use of microlattices with nanoscale features, combining great stiffness and strength with ultralow density, the authors say. The actual production of such materials is made possible by a high-precision 3-D printing process called projection microstereolithography, as a result of the joint research collaboration between the Fang and Spadaccini groups since 2008.

“We found that for a material as light and sparse as aerogel [a kind of glass foam], we see a mechanical stiffness that’s comparable to that of solid rubber, and 400 times stronger than a counterpart of similar density. Such samples can easily withstand a load of more than 160,000 times their own weight,” says Fang, the Brit and Alex d’Arbeloff Career Development Associate Professor in Engineering Design. So far, the researchers at MIT and LLNL have tested the process using three engineering materials — metal, ceramic, and polymer — and all showed the same properties of being stiff at light weight.

The material has the same weight and density as aerogel — a material so light it’s called ‘frozen smoke’ — but with 10,000 times more stiffness. This material could have a profound impact on the aerospace and automotive industries as well as other applications where lightweight, high-stiffness and high-strength materials are needed.

They used polymer as a template to fabricate the microlattices, which were then coated with a thin-film of metal ranging from 200 to 500 nanometers thick. The polymer core was then thermally removed, leaving a hollow-tube metal strut, resulting in ultralight weight metal lattice materials.

“We have fabricated an extreme, lightweight material by making these thin-film hollow tubes,” said Spadaccini, who also leads LLNL’s Center for Engineered Materials, Manufacturing and Optimization. “But it was all enabled by the original polymer template structure.”

The team repeated the process with polymer mircolattices, but instead of coating it with metal, ceramic was used to produce a thin-film coating about 50 nanometers thick. The density of this ceramic micro-architected material is similar to aerogel.

The LLNL-MIT teams’ new materials are 100 times stiffer than other ultra-lightweight lattice materials previously reported in academic journals.

Science – Ultralight, ultrastiff mechanical metamaterials

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