At present, the general development trend of armor materials is toughening, lightweight, multi-function and high efficiency. Alumina ceramic material is one of the most important bulletproof materials. It has high hardness and wear resistance, high compressive strength and excellent ballistic performance under high stress.

The bulletproof mechanism of alumina ceramic and metal is very different. Metal absorbs kinetic energy of projectile due to plastic deformation, while ceramic absorbs kinetic energy of projectile due to its fracture. Generally, the ceramic armor system is composed of a single piece of ceramic or ceramic-metal composite and a nylon cloth layer covered with high tensile strength organic fibers.

Under the impact of bullet, the front of alumina ceramic is broken and the remaining energy is absorbed by the soft reinforcement material on the back. The reverse material must be able to support the fragments of ceramic material and bullet itself after bullet impact. Of course, bulletproof ceramics require many properties, including density and porosity, hardness, fracture toughness, Young's modulus, sound velocity, 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, and the crack formation is caused by many factors, and the time of occurrence is very short.

The porosity of alumina bulletproof ceramics should be as low as possible to improve the hardness and Young's modulus; And its hardness requirement is very high, which should be higher than that of the flying warhead; The speed of sound propagation in alumina ceramics indicates the ability to consume energy on the impact surface of ceramics. High sound speed also indirectly indicates that ceramics have good densification and low sealing pores.

The existing bulletproof ceramics are mainly divided into two types, namely, monolithic ceramic structure and ceramic composite structure. Monolithic structural 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 is more advantageous than alumina ceramics as bulletproof. However, these materials are manufactured by expensive hot pressing, which is not easy to be industrialized. However, hot pressing can improve the mechanical properties of bulletproof ceramics.

Moreover, ceramic matrix composites have high bulletproof performance, which is due to their high mechanical properties, especially fracture toughness. After projectile impact, the ceramic matrix composite has better integrity than the monolithic ceramic. Therefore, alumina ceramics are very suitable for bulletproof ceramics.