Ceramics for ballistic protection

In an ongoing effort to reduce the weight of protective systems and improve their ease of use, combined with an ever-present concern to cut costs, new designs and materials have emerged. Ceramics, initially considered unsuitable for ballistic protection due to their extreme fragility, have become the preferred choice. Their integration into so-called "double-hardness" systems, in which the ceramic front face is supported by a more ductile layer, makes it possible to take advantage of their remarkable properties such as very high hardness, low density and high rigidity combined with excellent compressive strength.

The ballistic protection systems discussed in this article are designed to protect combatants (body armor), light armored vehicles (LAVs) and combat helicopters. What sets these three systems apart is that the weight of the protection in these systems is a critical, highly strategic parameter. The performance of the protection must be maximized, but its presence must not impact on the mobility and autonomy of either the soldier or the vehicle. The key parameter for these applications is therefore mass. It is also necessary to take into account the presence of human beings in contact with or in the immediate vicinity of the backing of the protection. So, although stopping the projectile is an expectation of the protection system, its behavior during an attack, and more particularly its deformation on the rear face, necessary for dissipating the energy of the threat and retaining the fragments formed, must also be known and perfectly controlled in order to avoid any shock and/or trauma to the military personnel present.

There are a considerable number of ceramics, but the ones most commonly used in ballistic applications are three in number: alumina (Al ₂ O ₃ ), silicon carbide (SiC) and boron carbide (B ₄ C).

The aim of this article is to introduce the ceramics used in ballistic protection systems. The first part is dedicated to the concept of ceramic armor, from its discovery to the mechanisms at play during a ballistic event, including a description of the different layers that make it up. We will see that the ballistic impact of a ceramic armor involves a large number of physical and mechanical properties, and that while the mechanisms involved are now known, the relationship between ceramic properties and ballistic performance is still not clearly established. Finally, the methods used to assess the ballistic performance of ceramics are briefly presented. The second section focuses on the three main ceramics used in the field. Their physicochemical and mechanical properties are detailed, and the...