In the world of superheroes, Captain America reigns as one of the most popular figures thanks in no small part to the original 1940’s comic book series as well as the recent string of films making up the Marvel Cinematic Universe. Serving as an effigy of American patriotism and strength since World War II, Captain America has held off Axis forces and other enemies mainly with the use of his shield, a bulletproof piece of equipment constructed from a vibranium steel alloy which is physically indestructible under normal conditions. In the recent Marvel series of films, U.S. Army Private Steve Rogers, the man who becomes Captain America, selects the disc-shaped prototype and finds that its ability to save his life is quickly tested.
Recent news reports suggest Captain America technology, particularly his shield, may be closer to becoming a reality than many might otherwise believe. With this in mind, as fans of Captain America and the Marvel Cinematic Universe are anxiously awaiting the release of Captain America: Civil War on May 6, 2016, we thought it might be an opportune time to unveil a new series — Superhero Tech.
Bullet Stopping Composite Metal Foam
A lightweight material which can be easily formed into armor has obvious applications in the worlds of military and defense. Much like Captain America’s shield, materials that can either deflect or absorb the kinetic energy of firearm ballistics could save lives and protect soldiers serving around the world. In early April, news reports of a bullet-stopping composite metal foam which can serve as a lightweight armor means that our nation’s military has taken a significant step towards developing Captain America-style armor.
The foam, which has a thickness of 25 millimeters (mm), was developed by researchers from NC State University and the U.S. Army Engineer Research and Development Center. NC State has worked on metallic foams for military armor applications in the past, announcing a high strength foam for body and vehicle armor applications last November. The more recent foam developed in concert with U.S. Army engineers has multiple layers including a ceramic strike face, Kevlar panel backplates and a composite metal foam which serves as interlayer which absorbs the kinetic energy which is delivered by a bullet. As this video posted by NC State shows, a bullet contacting the foam explodes, spreading out in a circular fashion without achieving any penetration of the layer.
To generate the energy absorbing foam interlayer, researchers utilized powder metallurgy techniques. Typical powder metallurgy methods for forming metallic composites involve mixing powdered alloys of metals like iron, aluminum or stainless steel. Once mixed, the powders are compacted by a die and then sintered in a controlled atmosphere furnace, both of which steps serve to produce an alloy material in a defined shape which doesn’t require further machining. Technically, powder metallurgy is a form of additive manufacturing which, much like 3D printing, can result in products manufactured with a high degree of precision without creating the waste materials that traditional manufacturing processes create. An industry report released by global market research firm Brisk Insights forecasts that the global market for powder metallurgy will grow by a compound annual growth rate of five percent between 2015 and 2022. More interest in the powder metallurgy industry is likely reflected in the recent redesign of the official website of the Metal Powder Industries Federation, the biggest web update for the trade federation’s site in almost 20 years.
The results of the composite metal foam experiments have produced results that greatly exceed armor piercing standards which are laid out by the National Institute of Justice (NIJ). The NIJ’s Perforation and Backface Signature Test (P-BFS) standards for armor models allow for a maximum depth of 44 mm during compliance testing. The NC State and U.S. Army Corps of Engineers composite metal foam created an indentation of 8 mm on the armor’s backplate, almost six times smaller than the maximum indentation depth allowed by the NIJ.
The composite metal foam stopping these bullets is less than one inch in thickness, which leads to the ability to craft armor which is much lighter in weight than other body armor solutions. This is very important in the military field where, as recently as 2009, it took 31 pounds of armor to completely protect soldiers from enemy fire, and even the minimum protective vest weighed 21 pounds on its own. The U.S. Army’s recent history with body armor has hit some snags, such as was the case with a January 2009 recall of 16,000 sets of body armor after a Department of Defense (DoD) report alleged flaws in the Army’s testing process. Inadequate body armor is a problem that costs American lives and as recently as 2006, a U.S. Pentagon study indicated that 80 percent of U.S. Marines who died in Iraq could have been saved with extra body armor which already existed at that time.
Supersoldier armor worthy of protecting Captain America is forthcoming from a separate research project involving members of the academic communities of both Rice University and the Massachusetts Institute of Technology (MIT). Researchers have been experimenting with microscale ammo to increase the body of knowledge surrounding block copolymers and how they are affected by sudden impacts from ballistics. The project has led to the realization that a polystyrene-polydimethylsiloxane diblock-copolymer, which self-assembles into layers of alternating glassy and rubbery polymers, melts into a homogenous liquid when contacted by a high-velocity object. This liquid actually served to trap microbullets and absorb the energy from their impact, technically allowing bullet penetration but eliminating most of the damage potential.
The dramatic nature of stopping a speeding bullet is always going to grab headlines and nudge the conversation in the direction of military and combat, but researchers from both of the above projects envision many more applications than that. Super light and strong materials could be useful in protecting electrical and scientific equipment floating in space from high speed projectiles. These materials could serve as containers for nuclear materials as they’re shipped or even provide lighter weight equipment for turbine blades and jet engines, both of which require incredible levels of durability. Metallic foams also have heat-resistant qualities which could provide more insulation in case of a fire.
Captain America and his vibranium steel alloy shield will next be on display in the upcoming Marvel Entertainment blockbuster Captain America: Civil War, which is releasing to movie theaters on May 6th. A partnership between Marvel and electronics distributor Mouser Electronics of Mansfield, TX, will seek to further blur the line between science fiction and real-world technology. An innovation video series hosted by Grant Imahara of MythBusters will take a STEM-oriented view at fabrication projects for technologies from the soon-to-be-released major motion film, including that famous shield which is as much a symbol of our nation’s resiliency as it is Captain America’s most trusted sidekick.
Image Source 123RF.com ID 19443164 © Carlos Valadas Carvalho