From the current point of view, the general development trend of armor materials is toughening, lightweight, multi-functional and high efficiency. Alumina ceramic materials are an important part of bulletproof materials. They have high hardness and wear resistance, high compressive strength and excellent ballistic properties 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. Typically, ceramic armor systems are composed of a single piece of ceramic or ceramic-metal composite covered with a layer of nylon cloth bonded 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 and the bullet itself after the bullet impact. Of course, bulletproof ceramics require many properties, including density and porosity, hardness, fracture toughness, sound speed, mechanical strength, etc. None of these properties can have a direct and decisive relationship with the overall bulletproof performance, so the fracture mechanism is very complex. Crack formation is caused by many factors and occurs over a very short period of time.

    The porosity of alumina bulletproof ceramics should be as low as possible to increase the hardness and Young's modulus; and its hardness requirements are very high, which should be higher than the hardness of flying warheads; the speed of sound propagation in alumina ceramics represents the impact surface of the ceramics The ability to consume energy, high sound velocity also indirectly indicates that the ceramic has good densification and low closed pores.

     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, which are more advantageous as ballistic protection than alumina ceramics. However, these material manufacturing methods mostly use expensive hot pressing and are not easy to be industrialized. But hot pressing can improve the mechanical properties of bulletproof ceramics.

Moreover, ceramic matrix composites have high ballistic resistance due to high mechanical properties, especially fracture toughness. After projectile impact, ceramic matrix composites have better integrity than monolithic ceramics. Therefore, alumina ceramics are very suitable as bulletproof ceramics.