Ceramic bulletproof sheet (bulletproof plate) is an important branch of the bulletproof sheet, it has many advantages that metal bulletproof sheet does not have, especially silicon carbide ceramics and high alumina ceramics, which have high hardness and wear resistance, Excellent ballistic performance of high compressive strength and high stress, it is a very popular bulletproof material at present.
There are two main types of bulletproof sheet materials that we commonly see now. The first is the metal bulletproof sheet: its production process is simple, but its density is high and its weight is heavy, which affects the use effect. When it resists the impact of a bullet, it will produce plastic deformation, absorb energy, and the bulletproof effect is not ideal. The other is ceramic bulletproof pieces. Bulletproof ceramics are mainly divided into three categories, namely oxide ceramics (mainly alumina ceramics), non-oxide ceramics (such as silicon carbide ceramics, silicon nitride ceramics, aluminum nitride ceramics, and boron carbide ceramics, etc.) and binary system (for example, B4C-TiB2 based ceramics).
Non-oxide ceramics have higher physical properties and relatively low density (except TiB2-based ceramics), but the manufacturing methods of these materials mostly use expensive hot-pressing technology, which is not easy for industrial production. The high alumina ceramic bulletproof plate is cost-effective and easy to mass produce.
For the performance requirements of ceramic bulletproof plates, because the fracture mechanism of ceramic bulletproof plates is complex, crack formation is caused by many factors, and the occurrence time is very short, so bulletproof ceramics require more performance, such as density, porosity, hardness, fracture toughness, elastic modulus, sound velocity, and mechanical strength, etc.
So, what is the bulletproof principle of ceramic bulletproof pieces? Let's first look at the system structure. The ceramic bulletproof system is composed of a monolithic ceramic or ceramic and metal composite covered with a high-tensile and high-strength organic fiber nylon cloth or glass fiber layer. Ceramics are bulletproof because of their high specific stiffness, high specific strength, and chemical inertness in many environments. When the high-speed projectile collides with the ceramic layer, the ceramic layer breaks or cracks and spreads around the impact point to consume most of the energy of the projectile, and then the high-modulus fiber composite plate further consumes the remaining energy of the projectile.
Ceramic bulletproof sheets have obvious advantages, among which alumina ceramics and silicon carbide ceramics have superior performance. Next, we will focus on introducing these two ceramics.
Alumina ceramic bulletproof plate:
This kind of bulletproof board uses industrialized ultra-fine alumina powder as the main material, and the aluminum oxide powder needs to be converted into a crystal structure, so the chemical properties are more stable. Due to the small size of the alumina powder, the sintered ceramic has a fine microstructure.
The porosity of bulletproof ceramics should be as low as possible to increase hardness and modulus of elasticity, which is excellent for alumina ceramics. Its porosity is close to zero, and its water absorption does not exceed 0.02%. The hardness of the bulletproof sheet is very high, it should be higher than the hardness of the flying warhead, and the hardness can reach above HRA88, which fully meets the requirements. The speed of sound propagation in ceramics indicates the ability of the ceramic to consume energy on the impact surface, so the bulletproof sheet hopes to have a high sound velocity, and a high sound velocity also indirectly indicates that the ceramic has good densification and low closed pores, and the sound velocity of alumina ceramics It can reach 10500~11500m/s, which has obvious advantages compared with other bulletproof sheets.
Silicon carbide ceramic bulletproof sheet:
SiC is a covalent compound. When carbon and silicon form SiC crystals, its basic unit is a tetrahedron, which is formed by stacking SiC tetrahedrons. Its hardness is quite high, second only to several super hard materials. Although the hot hardness of silicon carbide decreases with the increase of temperature, it is still much harder than corundum, and it is also very good as a bulletproof material.
Whether it is military training, tactical activities or actual combat, ceramic bulletproof panels are a very good choice.