On the effects of powder morphology on the post-comminution ballistic strength of ceramics

Abstract

In this paper in order to try and elucidate the effects of particle morphology on ballistic response of comminuted systems, a series of experiments were carried out via the use of powder compacts with differing initial particle morphologies. This approach provided a route to readily manufacture comminuted armour analogues with significantly different microstructural compositions. In this study pre-formed `fragmented-ceramic' analogues were cold-pressed using plasma-spray alumina powders with two differing initial morphologies (angular and spherical). These compacts were then impacted using 7.62-mm FFV AP (Förenade Fabriksverken Armour Piercing) rounds with the subsequent depth-of-penetration of the impacting projectile into backing Al 6082 blocks used to provide a measure of pressed ceramic ballistic response. When material areal density was accounted for via differing ballistic efficiency calculations a strong indication of particle morphology influence on postimpact ceramic properties was apparent. These results were reinforced by a separate small series of plate-impact experiments, whose results indicated that powder morphology had a strong influence on the nature of compact collapse.which have shown that this comminuted materialon further compactionthen provides a residual resisting strength with respect to penetration [7,8,9]. The concept of ballistic strength discussed in this paper is essentially a measure of the ability of armour to resist penetration following an impact event. A number of different approachesboth experimental and computationalhave been adopted to investigate such material response, with the ultimate aim of allowing improved armour (or munition) development from the resultant insight into armour behaviour. Holmquist et al. [10] undertook a series of experiments to investigate the defeat mechanismsfor SiC tiles impacted in a reverse ballistics configuration by 1-mm diameter Au long rods.By monitoring a variety of impact events via a flash X-ray system the authors were able to discern both the onset of the dwell-penetration transition and the nature of subsequent penetration. Interestingly, a non-linear penetration velocity was discerned in all cases, in line with computational simulations. This behaviour was attributed to the multi-stage nature of the ceramic failurewith impacted material being comminuted before penetration occurred.However, in this study the nature of this comminuted materialand its precise contribution to ballistic resistancewere not discussedsomething which will be investigated here.A recent study by Horsfall et al. [11] however, focused to a greater extent on the contribution of fractured materials. In this study Sintox ® FA tiles comprising 95% alumina were explosively comminuted within a confining steel frame. An in-situ Al 7018-T6 witness plate located directly beneath the tile allowed subsequent depth-of-penetration (DOP) testing [1,12, 13,14] without further disturbance of the comminuted material. Further, as a comparison, 80 m pure alumina powder was pressed in...

Impact resistance performance and structural optimization of lightweight composite target plate

“…The main reason for the wide application of ceramic materials in bulletproof armor [20][21][22] is that ceramic materials have the characteristics of lightweight, high strength, and low density. [23][24][25] The ceramic material is made of boron carbide ceramic, which belongs to brittle material, and its main damage form is brittle fracture.…”