Strengthening fabric armour with silica colloidal suspensions

This study investigates the ballistic performance of Twaron(R) CT615 plain-woven fabric impregnated with a silica colloidal water suspension (SWS) of different particle concentrations in water. The ballistic limits and specific ballistic energy of single, double, quadruple and six ply fabric systems impregnated with 0, 20, 40 and 50wt% SWS particle concentration are compared to that of a neat untreated system. Results show that systems with 40wt% SWS particle concentration yield the highest ballistic limit for single, double and quadruple ply systems, with the double ply system showing the greatest improvement. The ballistic limits of double ply systems with 40wt% SWS particle concentration is 70% higher than the ballistic limit of neat double ply systems. The improvement in ballistic resistance is attributed to the increase in projectile-fabric friction and inter-yarn friction arising from the silica particle and silica clusters formed. The impact energy at the ballistic limit is normalized by the areal density of the multi-ply systems to give the specific ballistic energy. The double ply system with 40wt% SWS particle concentration showed the greatest improvement with a 100% increase in the specific ballistic energy over neat double ply systems. However, the specific ballistic energy for quadruple and six ply systems with SWS is lower compared to the neat systems. High-speed photography showed that these systems experience more localized deformation on impact and this may limit the frictional effects. It is also shown that SWS impregnated double ply systems can be incorporated into six ply configurations to significantly improve overall ballistic performance. (C) 2004 Elsevier Ltd. All rights reserved.