Bullet resistant too... great for sunglasses sold on eBay.

http://www.af.mil/news/story.asp?id=123012131

Air Force testing new transparent armor

by Laura Lundin
Air Force Research Laboratory Public Affairs

10/17/2005 - WRIGHT-PATTERSON AIR FORCE BASE, Ohio (AFPN) -- Engineers
here are testing a new kind of transparent armor -- stronger and
lighter than traditional materials -- that could stop armor-piercing
weapons from penetrating vehicle windows.

The Air Force Research Laboratory's materials and manufacturing
directorate is testing aluminum oxynitride -- ALONtm -- as a
replacement for the traditional multi-layered glass transparencies now
used in existing ground and air armored vehicles.

The test is being done in conjunction with the Army Research Laboratory
at Aberdeen Proving Grounds, Md., and University of Dayton Research
Institute, Ohio.

ALONtm is a ceramic compound with a high compressive strength and
durability. When polished, it is the premier transparent armor for use
in armored vehicles, said. 1st Lt. Joseph La Monica, transparent armor
sub-direction lead

"The substance itself is light years ahead of glass," he said, adding
that it offers "higher performance and lighter weight."

Traditional transparent armor is thick layers of bonded glass. The new
armor combines the transparent ALONtm piece as a strike plate, a middle
section of glass and a polymer backing. Each layer is visibly thinner
than the traditional layers.

ALONtm is virtually scratch resistant, offers substantial impact
resistance, and provides better durability and protection against armor
piercing threats, at roughly half the weight and half the thickness of
traditional glass transparent armor, said the lieutenant.

In a June 2004demonstration, an ALONtm test pieces held up to both a
..30 caliber Russian M-44 sniper rifle and a .50 caliber Browning Sniper
Rifle with armor piercing bullets. While the bullets pierced the glass
samples, the armor withstood the impact with no penetration.

In extensive testing, ALONtm has performed well against multiple hits
of .30 caliber armor piercing rounds -- typical of anti-aircraft fire,
Lieutenant La Monica said. Tests focusing on multiple hits from .50
caliber rounds and improvised explosive devices are in the works.

The lieutenant is optimistic about the results because the physical
properties and design of the material are intended to stop higher level
threats.

"The higher the threat, the more savings you're going to get," he said.
"With glass, to get the protection against higher threats, you have to
keep building layers upon layers. But with ALONtm, the material only
needs to be increased a few millimeters."

This ability to add the needed protection with only a small amount of
material is very advantageous, said Ron Hoffman, an investigator at
University of Dayton Research Institute.

"When looking at higher level threats, you want the protection, not the
weight," Mr. Hoffman said. "Achieving protection at lighter weights
will allow the armor to be more easily integrated into vehicles."

Mr. Hoffman also pointed out the benefit of durability with ALONtm.

"Eventually, with a conventional glass surface, degradation takes place
and results in a loss of transparency," Mr. Hoffman said. "Things such
as sand have little or no impact on ALONtm, and it probably has a life
expectancy many times that of glass."

The scratch-resistant quality will greatly increase the transparency of
the armor, giving military members more visual awareness on the
battlefield.

"It all comes down to survivability and being able to see what's out
there and to make decisions while having the added protection," Mr.
Hoffman said.

The Army is looking to use the new armor as windows in ground vehicles,
like the Humvee, Lieutenant La Monica said. The Air Force is exploring
its use for "in-flight protective transparencies for low, slow-flying
aircraft. These include the C-130 Hercules, C-17 Globemaster III, A-10
Thunderbolt II and helicopters.

While some see the possibilities of this material as limitless,
manufacturability, size and cost are issues the lab is dealing with
before the armor can transition to the field, the lieutenant said.

"Traditional transparent armor costs a little over $3 per square inch.
The ALONtm Transparent Armor cost is $10 to $15 per square inch,"
Lieutenant La Monica said. "The difficulties arise with heating and
polishing processes, which lead to higher costs. But we are looking at
more cost effective alternatives."

Lieutenant La Monica said experimenting with the polishing process has
proven beneficial.

"We found that by polishing it a certain way, we increased the strength
of the material by two-fold," he said.

Currently, size is also limited because equipment needed to heat larger
pieces is expensive. To help lower costs, the lieutenant said
researchers are looking at design variations that use smaller pieces of
the armor tiled together to form larger windows.

Lowering cost by using a commercial grade material is also an option,
and the results have been promising.

"So far, the difference between the lower-grade material and higher
purity in ballistic tests is minimal," he said.

Lieutenant La Monica said once the material can be manufactured in
large quantities to meet the military's needs, and the cost brought
down, the durability and strength of ALONtm will prove beneficial to
the warfighter.

"It might cost more in the beginning, but it is going to cost less in
the long run because you are going to have to replace it less," he
said.

(Courtesy of Air Force Materiel Command News Service)


I'm wondering how long before this stuff is outsourced to china and then
the cheaper product used in vests and limos.