Ballistic behavior of alumina with niobia additions

The combination of hard and brittle ceramics with ductile materials is an efficient way of providing enhanced protection of armored vehicles against bullet penetration without losing mobility. For the first kind of material, alumina based ceramic compositions containing up to 6 wt% niobia were sintered at temperatures between 1400 degrees C and 1600 degrees C. The samples were characterized by x-ray diffraction, energy dispersive spectroscopy and fracture analysis using scanning electron microscopy. Elastic longitudinal and shear wave velocities were also measured. This material was submitted to ballistic test simulations using the 2D AUTODYNE Program, where a 7.62 mm AP projectile with 870 m/s impact velocity hit ceramic plates glued onto Al 6061-T6 aluminum blocks. The technique was used to study, in a systematic way, a variable that correlates projectile fragmentation with that of the target, thus quantifying the efficiency of each composition regarding ballistic protection. The results were used to evaluate the influence of niobia addition and sintering temperature on the densification, microstructure, and ballistic protection of alumina based ceramics.