Silicon Carbide and Boron Carbide Composite Ceramics(SiB4C)

Silicon Carbide and Boron carbide composite bulletproof ceramics possess good traits such as low density, high hardness, high modulus, and it has a high bending strength and fracture toughness, which is a better armor material. Silicon Carbide and Boron carbide composite bulletproof ceramics also has the characteristics of low density, light weight, high cost performance. The weight of Silicon Carbide and Boron carbide composite ceramics is only 30% of steel, which is 30% lighter than alumina ceramics, so boron carbide ceramics is widely used in individual soldier protection, in all kinds of low-altitude aircraft and in some armored vehicles. It is also known as boron carbide composite ceramics.

Silicon carbide (SiC) ceramics and Boron Carbide (B4C) are typical super hard materials and high performance ceramic materials, which have a wide range of applications. With high melting point, high hardness, good thermal and electrical conductivity, they can be widely used in tool materials and high temperature structural materials. However, due to their very strong covalent bonds, they are extremely difficult to be sintered into dense ceramic materials.

Sintering is an important step in the process of ceramic preparation. Common sintering processes are divided into pressureless sintering, hot pressure sintering and reaction sintering. These techniques can promote the densification and decrease the sintering temperature of complex phase boron carbide ceramics, thus improving the properties and stability of the materials.

Reactive sintering of Silicon carbide and Boron Carbide composite ceramic is a method that can obtain dense sintered body at low temperature in vacuum by siliconizing reaction. The method is to mix carbon powder with boron powder and react sinter at high temperature. By controlling the reaction temperature and time, carbon powder and boron powder react to produce boron carbide during the reaction sintering process. Complex phase boron carbide ceramics with certain properties can be obtained. The preparation of SiC-B4C multiphase ceramic materials by reaction sintering at low temperature is an effective method to obtain compact ceramic materials at low cost.

The process of pressureless sintering Silicon Carbide and Boron carbide composite ceramic is divided into three stages: dry press and drying, pre-firing and sintering.

The matching material is put into the mold and pressed into shape by a special pressure device. The formed body needs to maintain a certain strength and toughness to avoid cracking in the subsequent processing.

The green body is placed in the oven for drying to remove the moisture and volatiles inside and on the surface, making it more suitable for sintering.

The dried body is put into the sintering furnace, and it is heated to reach a certain temperature and atmosphere conditions for sintering. In the sintering process, it is necessary to control the appropriate temperature, time and sintering atmosphere to ensure the density and stability of the sintered body. After sintering, it is necessary to carry out cooling, cutting, grinding and other processing.

Silicon Carbide and Boron carbide composite ceramic has many advantages such as high hardness, high wear resistance, high melting point, high temperature resistance, excellent thermal conductivity, excellent chemical stability, good electrical insulation, light weight, high strength and low thermal expansion coefficient. These properties make boron carbide a widely used material in high temperature, high pressure, high wear resistance, corrosion resistance and high electrical insulation requirements. Regarding lightness and strength, complex phase boron carbide has a relatively low density of about 2.65±0.5g/cm³, which is lighter than iron and steel. Although the performance is slightly weaker than that of hot-pressed boron carbide, this makes Silicon carbide and Boron carbide composite ceramic an ideal choice for the manufacture of lightweight structural parts and composite materials. After all, the price is cheaper and the output is increased. Therefore, Silicon Carbide and Boron carbide composite ceramic has been favored by military experts in various countries and has been used by the high-end market.

Because of its light weight, ultra-high hardness and high elastic modulus, Silicon Carbide and Boron carbide composite ceramics are the best materials for bulletproof vests, bulletproof helmets and bulletproof armor. Compared with aluminum oxide ceramics and silicon carbide ceramic bulletproof materials, SiB4C ceramics are lighter and harder, especially suitable for human protection, gunship helicopters and other aircraft as bulletproof armor materials, which can effectively withstand bullets and shells. Therefore, B4C ceramics are generally only used in some special occasions with high requirements for protective properties. In addition, the Enhanced Human armor (EBA) used by the British Army also uses boron carbide ceramics, which can protect against 12.7mm steel core piercing bullets. Silicon carbide and Boron Carbide composite ceramic is a low cost and mass-produced small protective armor plate developed specifically against the low yield and high price of hot pressed boron carbide.