Carbon fiber bulletproof

[Jake]

Hey all,

I wonder if anyone can answer this for me:

Why hasn't carbon fiber been used to make better bulletproof vests (ignoring cost)? Doesn't carbon fiber have a higher tensile strength than Kevlar? Isn't it lighter?

Also, wouldn't a solid version, of carbon fiber reinforced plastic, as thick as an infantry armor plate, also provide great protection?

And how about Carbon Fiber Reinforced Ceramic? Wouldn't that be the ultimate protection? Is there anyway to do this?

These questions have been nagging me for a while, and I can't find anything on the internet. I don't really need this for school or anything, but I figured I'd bring it up anyway :)

Thanks :)

[turbo-1]

Kevlar is used because it is strong and cheap, and can be woven into flexible cloths that can be laminated. A bulletproof vest is not some monolithic material. It is made of materials that can be stacked in thin light layers, that can slow a bullet while spreading its shock over wider and wider areas (which is where the layers come in). There are other very strong fiber materials that can be used, but so far carbon's brittle nature has made it unsuitable for armor. Carbon nano-tubes might one day be woven into suitable strong light fabrics, but it is horrendously expensive now, and would probably require a lot of designing, engineering, and testing to make a safe vest.

Kevlar, while not dirt-cheap is a very strong Aramid fiber that can be mass produced easily, and it is commonly available in consumer products, like the yellow cut-resistant woven gloves you can get at industrial-supply places and food-industry supply places.

[Jake]

Hey Turbo,

So it is the brittelness specificly that prevents carbon fiber from being used in vests as a replacement for Kevlar?

I can't visualize this though; carbon fibers still can flex a great deal, much more than a vest actually moves when hit by a bullet. And the whole point of Kevlar is its high tensile strength, which carbon is higher in, so I still don't see what the obstacle is.

[turbo-1]

Kevlar is VERY tough and flexible, and the fibers can be twisted to increase the density and integrity of the woven cloth. This is a major advantage in application. It's important to keep the weave dense enough to reduce projectile penetration, and the more layers can remain intact, the more they will help redistribute (spread out) the force of the impact, reducing blunt-force trauma. A cop might get shot with a pretty high-powered round, and still have heavy contusions, broken ribs, etc, even though the bullet didn't penetrate through the vest.