Microbullet hits confirm graphene's strength at Rice University

what we explored was the ability of thin graphene sheets and represented by this black film to stop a projectile represented by this ping-pong ball and the size of the actual projectile it's a micro bullet it's only about three microns in diameter a human hair is around 50 microns so this is considerably thinner than you know like a tenth of the size of a human hair and the thinness of the membrane is also down on the scale well below human hair and the size of the sphere relative to the thickness of this membrane is about what we do in our experiments we shoot this sphere at a very high rate around a kilometer per second so bullets typically are below a kilometer per second in speed and the sphere at these high rates carrying kinetic energy impacts this thin membrane presses against it pushes it forward and a cone of deformation develops with the sphere at the center and because graphene is very very strong and it's very very stiff and it's very very low density this cone spreads out quite a distance in the material and the kinetic energy the sphere is transferred to the membrane before it pushes through and then eventually exits on the other side and in our experiments we can measure the velocity and therefore the kinetic energy of the sphere in front of the membrane before it hits and after it's passed through the membrane and therefore calculate the difference in those two energies as the energy that was required to pass through the membrane and when we compare the behavior of graphene thin films to that of other materials for example steel on an equal weight basis graphene is 10 times better than steel at absorbing energy out of micro bullets so one of the characteristics of a material that is dissipating a lot of energy is the amount of material that's involved in the in the penetration event what we've shown here in these these images is a material which doesn't absorb very much energy in this case it just has a circular hole the same size as a sphere where the spirit rated through without losing much energy and also we have pictures of the graphene films which are much stronger and absorb much more energy and you can see the extensive damage which is in an area several diameters of the sphere bigger than the size of the sphere you could kind of demonstrate this at home when you wanted to look at if you trying to punch through a piece of paper it will make a small hole whereas if you push against something like a stretchy piece of saran wrap will deform a large cone and then eventually punch through but the deformation of the film will be much more extensive and the energy it took to push through this rayon if it was on the same thicknesses of paper would be a lot more we've understood some of the principles of what makes graphene such a excellent protection material and because graphene is so lightweight it could be employed for ballistic protection for the warfighter and even in satellites in the space station for protection against micro meteorites you

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Keywords: Rice University, Rice, Houston, Texas, College, University, Education, Students, Higher Education

Id: Sevm_DHu05o

Length: 3min 20sec (200 seconds)

Published: Mon Dec 01 2014