Alumina ceramics have the characteristics of bulletproof materials
From the current point of view, the general development trend of armor materials is toughness, light weight, multi-function and high efficiency.Alumina ceramic material is an important part of bulletproof materials. It has high hardness and wear resistance, high compressive strength and excellent ballistic performance under high stress.
The bulletproof mechanisms of alumina ceramics and metals are very different. Metals absorb the kinetic energy of projectiles due to plastic deformation, while ceramics absorb the kinetic energy of projectiles due to their rupture. Generally, the ceramic armor system is composed of a single piece of ceramic or ceramic-metal composite and covered with a nylon cloth layer combined with high tensile strength organic fibers.
Under the impact of the bullet, the front side of the alumina ceramic is broken and the remaining energy is absorbed by the soft reinforcement material on the back side. The back side material must be able to support the fragments of the ceramic material after the bullet impact and the bullet itself. Of course, as bulletproof ceramics, there are many properties required, including density and porosity, hardness, fracture toughness, Young's modulus, sound velocity, mechanical strength, etc., none of the properties can have a direct and decisive relationship with the overall ballistic performance. The fracture mechanism is very complicated, the formation of cracks is caused by many factors, and the time of occurrence is very short.
The existing bulletproof ceramics are mainly divided into two categories, namely monolithic ceramic structure and ceramic composite structure. Monolithic structure ceramics include oxide ceramics and non-oxide ceramics, as well as binary systems. Generally speaking, non-oxide ceramics have higher physical properties and relatively low density, and are more advantageous than alumina ceramics as bulletproof. However, these material manufacturing methods mostly use more expensive hot pressing, which is not easy to industrialize. But hot pressing can improve the mechanical properties of bulletproof ceramics.
In addition, ceramic matrix composites have high ballistic performance due to their high mechanical properties, especially fracture toughness. After the impact of the projectile, ceramic matrix composites have better integrity than monolithic ceramics. Therefore, alumina ceramics are very suitable as bulletproof ceramics.