Metal so ethereal it can balance on top of a dandelion

April 2016 - A typical high school physics class experiment has students build a structure that will protect a raw egg from cracking when dropped from a few stories above the ground. A similar concept applies to experiments by a DARPA award-winning laboratory except the padded, bulky solution is not necessary. Protection and strength are supplied by metal so immaterial, it can rest atop a dandelion seed head without disturbing it.

Since first publishing a paper on their discovery in 2011, HRL Laboratories Senior Scientist Tobias Schaedler and his team of researchers have been developing and scaling up the process for a microlattice alloy, says research scientist Dr. Sophia Yang. 

According to Malibu, California-based HRL, the focus is to “develop ultralight sandwich panels based on our ultralight lattice core materials. Attaching thin, stiff facesheets to the top and bottom surfaces of a relatively thick, lightweight core makes is the recipe. Sandwich structures provide high torsional and bending rigidity at low weight and have become the standard for lightweight design in the aerospace industry.” While foam and honeycomb cores are in use today, “additional weight savings and performance increases are sought from advanced cores.”

Moving forward from the initial finding—that less is more—Yang says scientists are studying how the microlattice, typically made from aluminum, will handle high temperatures, such as within an engine turbine. “For extreme temperatures, we can convert the microlattice to other materials (higher temperature alloys, ceramics) to handle the environment,” Yang says. 

HRL, which has support from huge OEMs like Boeing, BAE Systems, General Motors and the government—the Office of Naval Research is a client—has also conducted research on nickel phosphorous in a microlattice structure for aerospace and automotive functions.

From lab to real life

“We are investigating using microlattice for a number of applications,” Yang says. Although she is prevented from disclosing any specifics, “the microlattice could be used to replace core materials such as honeycomb [structures].” These are hexagonal-shaped natural or manmade structures formed in metal alloys, fiberglass and composite materials, used to provide strength. 

While still in the research stages, Yang suggests, “The capital investment for manufacturing these materials is not very high—no large autoclaves are required. The basic process is cost competitive to standard automotive part processes.”

The industry remains hopeful about such discoveries because lightweighting is the mandate for so many products. Although researchers continue to expand on the novel material, commercialization may not come about as quickly as manufacturers wish, according to Yang. “We’re still developing and testing this material for specific applications,” she says. “It may take another 5-plus years.” MM