Sintered silicon carbide(SiC) ceramics without pressure

Silicon carbide (SiC) ceramics is a kind of high performance ceramic material, which has a wide range of applications. Sintering is an important step in the preparation of SIC ceramics. It is mainly divided into non-pressure sintering, atmosphere sintering, hot press sintering, microwave sintering, reaction sintering, hot isostatic sintering, discharge plasma sintering, melt impregnation method and hydrothermal method. These technologies can promote the densification of SIC ceramics and reduce the sintering temperature, thus improving the performance and stability of the material.
 

The sintering process of non-pressure sintering silicon carbide is divided into three stages: dry press molding 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 molded 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 ceramics have excellent high temperature resistance, corrosion resistance, wear resistance and other properties, and are widely used in aerospace, automotive, energy, chemical and other fields. Because it has excellent mechanical properties, oxidation resistance, wear resistance and low friction coefficient, in addition to its good thermal stability, thermal expansion coefficient is small, thermal conductivity, thermal shock resistance and chemical corrosion resistance, it has been favored by military experts in various countries, and is widely used.

The basic principle of personal protection and armor protection is to dissipate the energy of the bullet, slow it down, and render it harmless. Most traditional engineering materials, such as metal materials, absorb energy through the plastic deformation of the structure, while ceramic materials absorb energy through the micro-crushing process.
 

The energy absorption process of silicon carbide bulletproof ceramics can be roughly divided into three stages:
 

(1) Initial impact stage: the bullet hits the ceramic surface, blunts the bullet, and absorbs energy during the process of crushing the ceramic surface to form a small and hard fragment area;

(2) Erosion stage: the blunted bullet continues to erode the fragment area, forming a continuous layer of ceramic fragments;

(3) Deformation, crack and fracture stage: Finally, tensile stress in the ceramic cracks, and then the backplane deforms, and the remaining energy is absorbed by the deformation of the backplane material. When the bullet hits the ceramic, both the bullet and the ceramic are damaged.

Silicon carbide ceramics use its special physical properties, in the field of bulletproof shine, especially non-pressure sintered silicon carbide ceramics become a very popular bulletproof material. Because of its small density and light weight, it has obvious advantages in bullet-proof equipment for individual soldiers, and is mostly used in bullet-proof jacket lining or single-defense inserts. It can also be used in protective devices for tanks and armored vehicles.