General explanation of the Reaction Bonded SiC

General explanation of the Reaction Bonded SiC

Reaction Bonded SiC has mechanical properties and oxidation resistance. Its cost is relatively low. In present society, it has attracted more and more attentions in various industries.

SiC is a very strong covalent bond. In sintering, the diffusion rate is very low. At the same time, the surface of the particles often covers a rather thin oxide layer which plays the role of the diffusion barrier. Pure SiC is hardly sintered and compact without sintering additives. Even if the hot-pressing process is used, it must also select suitable additives. Only at very high temperatures, can materials suitable for engineering density close to theoretical density be obtained which should be in the range from 1950 ℃ to 2200 ℃.At the same time, its shape and size will be limited. Although SIC composites can be obtained by vapor deposition, it is limited to preparing low density or thin layer materials. Because of its long quiet time, the cost of production will increase.

Reaction Bonded SiC was invented in 1950s by Popper. The basic principle is:

Under the action of capillary force, liquid silicon or silicon alloy with reactive activity penetrated into porous ceramics containing carbon and formed carbon silicon in the reaction. The newly formed silicon carbide is bonded to the original silicon carbide particles in situ, and the residual pores in the filler are filled with the impregnating agent to complete the densification process.

Compared with other processes of silicon carbide ceramics, the sintering process has the following characteristics:

Low processing temperature, short processing time, no need of special or expensive equipment;

Reaction Bonded parts with no shrinkage or change of size;

Diversified molding methods (extrusion, injection, pressing and pouring)。

There are more methods for shaping. During sintering, large size and complex products can be produced without pressurization. The Reaction Bonded technology of silicon carbide has been studied for half a century. This technology has become one of the focuses of various industries due to its unique advantages.