Nickel Lattices Form Lightest Material

Materials scientists have been inspired by human architectural feats like the Golden Gate Bridge and the Eiffel Tower which demonstrate light-weight structures relative to their size. After applying similar architectural principles at the micro and nano scales, they have have created the lightest material on Earth.

Ultralight metallic micro-lattices are so light that a block of them can balance on the top of a dandelion without crushing the delicate seeds. Engineers at University of California, Irvine, Cal Tech and HRL Laboratories have created a material that is 99.99 percent air and 100 times lighter than styrofoam.

According to a spokesman for HRL Laboratories, a research venture owned by General Motors and Boeing, this new material redefines the limits of lightweight materials because of its unique micro-lattice cellular architecture, which uses an innovative fabrication process developed by HRL senior scientist Alan Jacobsen.

And it gets even stronger when it is compressed. Scientists discovered that it’s not the nickel that gives the material its strength but its shape. The lattice structure gets stronger as it is compressed to half of its size.

Lorenzo Valdevit says, “Materials actually get stronger as the dimensions are reduced to the nanoscale.”

And the ultralight metallic micro-lattice utilizes a tube within tube technique using lasers to coat plastics in metal and then remove the polymer, leaving a metal tube with a wall thickness 1,000 times thinner than a human hair. The tiny hollow tubes are made of nickel-phosphorous and are angled to connect at nodes, forming repeating, asterisklike unit cells in three dimensions.

This metal nano-mesh is also incredibly resilient. If you’ve ever tried to recover metal’s shape after bending it or squishing it, you know it is nearly impossible. Yet, this new material can recover 98 percent of its shape after being reduced to 50 percent compression. That’s remarkable.

The collaborators on the project are looking at all sorts of applications for this new nano-mesh. They include thermal insulation, battery electrodes, catalyst supports, and acoustic, vibration, or shock energy damping. However, since the grant money to do this project came from the Defense Advanced Research Agency it is more likely that the material — which will be very costly to make — will be directed toward military applications like lightweight combat vehicles, space travel and combat armor.

Until the metallic micro-lattice was invented, aerogels were the lightest solid material on Earth. But they had some engineering flaws because when gas was used to replace the liquid in the structure the chaotic architecture left the aerogel less sturdy than the original parent material.

The researchers are now looking at making micro-lattices from other materials including, diamond, polymers and ceramics. They say they should be able to make lattices from any thin-film material.

The paper appears in the current issue of the journal Science.