We measured the ballistic performance of five ceramic materials (alumina, s
ilicon carbide, boron carbide, aluminum nitride, and titanium diboride) and
Pyrex, when they are backed by thick steel plates. The projectile for all
tests was a right-circular cylinder of tungsten sinter-alloy W2 with length
25.4 mm and diameter 6.35 mm, fired at velocities from 1.35 to 2.65 km/s.
For this threat we determined the minimum areal density of each material th
at is needed to keep the projectile from penetrating the backup steel. For
all of the facing materials studied here, this performance measure increase
s approximately linearly with projectile velocity. However, the rate of inc
rease is significantly lower for aluminum nitride than for the other materi
als studied. Indeed, aluminum nitride is a poor performer at the lowest vel
ocity tested, but is clearly the best at the highest velocity. Our computer
simulations show the significant influence of the backing material on cera
mic performance, manifested by a transition region extending two projectile
diameters upstream from the material interface. Experiments with multiple
material layers show that this influence also manifests itself through a si
gnificant dependence of ballistic performance on the ordering of the materi
al layers. (C) 1999 Elsevier Science Ltd. All rights reserved.