The lab
is working to improve transparent bulletproof armor for vehicles and
face shields, as well as lighter weight bulletproof windows, with the
development of a new, moldable material. The material, spinel, which
is more durable than glass, could significantly improve military defenses
as it is produced for various uses.
“Spinel is actually a mineral; it’s magnesium aluminate,”
said Dr. Jas Sanghera, the researcher leading the project. “The
advantage is it’s so much tougher, stronger, and harder than glass.
It provides better protection in more hostile environments—so
it can withstand sand and rain erosion. For weight-sensitive platforms-UAVs,
head-mounted face shields—it’s a game-changing technology.”
The NRL developed a method to make spinel, a gemstone that can be mined
in a variety of colors, transparent and produce it in sheets. The low-temperature
process, called sintering, uses a hot press to mold the material. The
technology is scalable, limited only by the size and shape of the press.
Using shaped presses, such as a ball-and-socket press, the spinel can
be made in to multiple shapes, such as a wing for an unmanned aerial
vehicle. At the NRL, pieces were made 8 inches in diameter, but an outside
company was able to use the technology to create much larger plates,
so far up to 30 inches.
“You put the powder in [a hot press], you press it under vacuum,
squash this powder together—and if you can do that right, then
you can get rid of all the entrapped air, and all of a sudden it comes
out of there clear-looking,” Sanghera said.
Other researchers have attempted sintering spinel, but the method did
not yield clear, usable sheets. NRL reworked the process with more pure
chemicals and a more uniformly mixed powder and the spinel produced
is clear. The spinel made by the NRL is polycrystalline, which means
a lot of crystal particles are pressed together to create the material.
This is significant because, while it might chip, it will not crack
the way glass does. It can be also be developed as a camera lens that
can hold up in a sandstorm or used to protect infrared and other cameras.
Spinel can be ground and polished, like gems, to increase optic quality.
And, spinel allows infrared light to pass through it, which makes it
optimal for military imaging systems. Glass does not transmit infrared
light, so the NRL has been developing new optical materials to replace
the soft and fragile optics used today.
The NRL is investigating additional uses for spinel, including laser
applications and use on space satellites. Researchers said the ultimate
goal is to hand the technology over to industry. But, the laboratory
is also looking to reduce the finishing cost so it can be affordable
to both the Department of Defense (DoD) and private industry. |
Researchers
are developing a transparent, bulletproof material that is more durable
than glass and can be molded into numerous shapes.