The aim of this work is to present results of mechanical characterization and ballistic test of alumina-based armor plates. Three compositions (92, 96, and 99 wt% Al2O3) were tested for 10 mm thick plates processed in an industrial plant. Samples were pressed at 110 MPa and sintered at 1600°C for 6 h. Relative density, Vickers hardness, and four-point flexural strength measurements of samples after sintering were performed. Results showed that the strength values ranged from 210 to 300 MPa depending on the porosity, with lower standard deviation for the 92 wt% Al2O3 sample. Plates (120 mm × 120 mm × 12 mm) of this composition were selected for ballistic testing according to AISI 1045, using a metallic plate as backing and witness plates in the case of penetration or deformation. Standard NIJ-0108.01 was followed in regard to the type of projectile to be used (7.62 × 51 AP, Level IV, 4068 J). Five alumina plates were used in the ballistic tests (one shot per plate). None of the five shots penetrated or even deformed the metal sheet, showing that the composition containing 92 wt% Al2O3 could be considered to be a potential ballistic ceramic, being able to withstand impacts with more than 4000 J of kinetic energy.

A combinação de propriedades físicas e mecânicas qualificam as cerâmicas para aplicações em sistemas de proteção balística. Materiais cerâmicos normalmente formam a primeira camada de um sistema de blindagem mista, recebendo o impacto inicial do projétil, e dissipando grande parte da energia cinética ao fragmentar o projétil. Os principais materiais cerâmicos para blindagem balística são a alumina, o carbeto de silício e o carbeto de boro. Novas técnicas de processamento de materiais cerâmicos além do modelamento do mecanismo de fratura sob alto impacto energético são áreas que têm sido amplamente investigadas. Desenvolvimentos em particular na área de compósitos de matriz cerâmica, reforçados com fibras ou com base na transformação por tenacificação abrem novas perspectivas de uso e de melhor desempenho de sistemas de proteção balística a base de materiais cerâmicos.

New ballistic protection systems based on alternative materials have been recently developed. One of the industry’s objectives is to develop lighter and stronger defensive systems, which allow higher mobility and safety for both vehicles and humans. This work studies the behavior of an aerospace protection against a projectile impact, seeking an optimized construction. The Al-Qureshi et al. model suggests a ceramic-metal layer system and describes its behavior. The literature shows, due to the considered parameters, the erosion tax and the loss of velocity. The phenomenon is described in steps, presenting particular effects for each. The equations are not equal between the stages showing different properties. The present work searches for a solution that can show the expression for mass and velocity, for each stage of the phenomenon. The results from the numerical method used were plotted and analyzed. The treatment was performed using Maplesoft Maple software. As a result, graphs were generated, which allow a deeper analysis of the model. Finally, advance in the knowledge of fracture processes in materials by high velocity impact can be concluded. This fact permits developments in materials that can perform shock absorption.

The behavior of ceramic-metal protection against a projectile impact is modeled. The model takes into account the mass and velocity for each stage of the phenomenon. A former model was modified considering more realistic parameters such as geometries and deformation profile. To analyze the model, simulations on different parameters have been run. The impact results of different ballistic projectiles were simulated, and the movement was plotted. In addition, a deterministic simulation on the mechanical properties of the back metal plate properties was done.

Experimental tests which match the application conditions might be used to properly evaluate materials for specific applications. High velocity impacts can be simulated using light-gas gun facilities, which come in different types and complexities. In this work different setups for a one-stage light-gas gun facility have been numerically analyzed in order to evaluate their suitability for testing materials and composites used as armor protection. A maximal barrel length of 6 m and a maximal reservoir pressure of a standard industrial gas bottle (20 MPa) were chosen as limitations. The numerical predictions show that it is not possible to accelerate the projectile directly to the desired velocity with nitrogen, helium, or hydrogen as propellant gas. When using a sabot corresponding to a higher bore diameter, the necessary velocity is achievable with helium and hydrogen gases.