THE MATERIALS DIFFERENCE
produce better batteries overall. Unfor- tunately, the thin layers are not placed where they need to be, but rather are
“formed in place” during manufacturing. Controlling formation and degradation mechanisms are active areas of research, but new materials can improve these processes and sustain optimal bat- tery performance.
Another example is Soldier protection. Stopping ballistic or blast threats takes more than just run-of-the-mill materials. While the helmet concept is nearly as old as war itself, understanding its dependence on atomic mechanisms has taken time. Today, science and technology improve- ments are at a threshold. Helmet designs are factoring in early atomic concepts— those that explain material characteristics of metals, foams, textiles, and plastics—to find the right combinations that offer the greatest degree of protection. Knowledge gained through such efforts has yielded updates to the battle-proven Army Com- bat Helmet.
Refining this knowledge for future updates will be limited, however. Innovative hel- met concepts call for lightweight materials that can redirect a bullet or shock wave in a split second (nanoseconds), thus reduc- ing or averting injury. This will not come from merely a better design recipe. Better material ingredients are needed.
New materials lie on the critical path to these and many other game-changing capabilities. Discoveries of materials and the means to make them would enable new paradigms for tactical operations and strategic maneuvers by allowing longer missions, improving situational awareness, and reducing risks in all aspects of Army operations. To these and many other ends, Army scientists and engineers have been in a race to exploit the influence of atomic mechanisms on materials.
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LOOKING AHEAD, THROUGH A WALL
Opportunities for leap-ahead innovations abound in a wide range of areas of interest to the Army, including through-wall imaging. Sense Through the Wall is an emerging technology managed by Program Executive Office (PEO) Soldier that detects moving and stationary targets through walls, floors, or ceilings as thick as 8-inch reinforced concrete. (Photo courtesy of PEO Soldier.)
SMALL ATOM, BIG CHALLENGE To illustrate how materials science works, imagine what happens when marbles are poured into a bin. Do so slowly enough, and ideally they begin to pack the bin in a nicely spaced array or lattice. In a large enough bin with the marbles poured in faster, perfect arrangements become less likely. Large regions of nicely ordered marble lattices may be separated by regions of haphazard packing.
The multiscale materials problem arises from the natural aversion of atoms to organize into orderly lattices, much like the marbles. Nature pours the atoms into their bins faster than they are able to arrange into lattices. At larger scales, this disorganization begins to show hierarchi- cal structure. The structural distinctions impart properties to the material that differ significantly from those of the
homogeneous perfect lattice. Control- ling the proportion of disorganized-to- organized spaces can yield exquisite control over the material’s properties. Metaphori- cally, this is dialing a “knob” to get, say, desired effects in electrical or dynamic behavior, such as lower electrical resistiv- ity or higher mechanical failure resistance.
Of course, the technical details are much more complicated, and many more cre- ative “knobs” are in the offing. History shows that discovering and engineering these “knobs” can lead to technological revolutions. Roughly speaking, the steel used to build skyscrapers and the silicon found in modern microprocessors owe their unique properties to controllable features in the material’s structure at the atomic scale. Exploited multiscale fea- tures in materials have had more recent impacts on diverse products including pharmaceuticals and digital cameras.
Army AL&T Magazine
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