New materials are as light as "frozen smoke" but 10,000 times stiffer

New materials are as light as "frozen smoke" but 10,000 times stiffer

Researchers have worked out how to 3D print super-stiff materials that are lighter than aerogel, and could revolutionise the aerospace and automotive industries.

Image: Ryan Chen/Lawrence Livermore National Laboratory

The new materials are as light as aerogel, a synthetic porous material that's the lowest known density solid - but 10,000 time tougher. They were created by researchers from Lawrence Livermore National Laboratory and Massachusetts Institute of Technology (MIT) in the US using an additive micro-manufacturing process. 

This means that the researchers first create 3D microscale super-tough "building blocks", so that the strength comes from the materials' geometric layout rather than their chemical composition.

Using this method, the researchers created materials out of polymer, metal and ceramic lattices that are unlike anything found in nature. The lightest of these is a ceramic-based material.

Most materials lose their mechanical properties as they get lighter because their structural elements are more likely to bend under extreme pressure. But the materials created using this new technique maintain a nearly constant stiffness per unit mass density, even at ultraslow densities, and could be used to create lightweight and super tough parts for aircrafts, space vehicles and cars. 

The team's research has been published in Science.

"These lightweight materials can withstand a load of at least 160,000 times their own weight," said Xiaoyu "Rayne" Zheng, lead author of the paper article from Lawrence Livermore National Laboratory, in a press release. "The key to this ultrahigh stiffness is that all the micro-structural elements in this material are designed to be over constrained and do not bend under applied load."

Even better, they were created using a 3D desktop printer.

To begin with, the researchers first created a polymer core that acted as template for the microlattices. This was then coated with a thin-film of metal that ranged from 200-500 nanometres thick and the polymer was removed, leaving a light, tough tube of metal lattice material.

They then repeated the process with a 50-nanometre-thick ceramic coating. This resulted in a material around the same weight as aerogel, or frozen smoke, which holds the most word records of many material - in fact, the record holding graphene aerogel is 7.5 times lighter than air.

Image: Aerogel by JovanCormac/Wikimedia

"It's among the lightest materials in the world," co-author Chris Spadaccini said of the new ceramic material. "However, because of its micro-architected layout, it performs with four orders of magnitude higher stiffness than aerogel at a comparable density."

The team also created polymer-ceramic hybrid microlattice, with similar properties. According to the new paper, these materials are 100 times stiffer than other ultra-lightweight lattice materials previously reported in academic journals.