Sintering method of SiC ceramics

Today, we are going to introduce silicon carbide ceramic, which is the best high temperature strength ceramic material, and its oxidation resistance is also the best of all non oxide ceramics, so it is widely used in various industrial fields. The following content is the three common sintering methods of silicon carbide ceramics.

Silicon carbide ceramics — pressureless sintering
In 1974, GE company in the United States tried to add a small amount of B and C to high-purity β – SiC fine powder, and used the pressureless sintering process to successfully obtain high-density SiC ceramics at 2020 ℃. This process has become the most important method to prepare SiC ceramics.
Now there are researchers who add Y2O3 and Al2O3 to submicron SiC powder to realize dense sintering of SiC at 1850 ℃ to 2000 ℃. Because the sintering temperature is relatively low and the microstructure is obviously refined, its strength and toughness are greatly improved.

Silicon carbide ceramics — hot press sintering
In the mid-1950s, Norton company in the United States began to study the influence of metal additives such as Ni, Cr, B, Al, Fe on the hot pressing sintering of SiC. The results show that de and Al are the most effective additives to promote the densification of SiC. Some people use Al2O3 as additive, through the sintering process of hot pressing, the densification of SiC has been realized successfully, and the mechanism is considered to be liquid phase sintering. In addition, B4C, B or B and C, Al2O3 and C, Al2O3 and Y2O3, be, B4C and C were used as micro additives respectively, and dense SiC ceramics were successfully obtained by hot pressing sintering.

Silicon carbide ceramics hot isostatic pressing sintering:
In recent years, in order to further improve the mechanical properties of SiC ceramics, many researchers have studied the hip process of SiC ceramics, using B and C as additives, and using the hip sintering process, high-density SiC sinters have been successfully obtained at 1900 ℃. Furthermore, the densification sintering of additive free SiC ceramics was successfully realized at 2000 ℃ and 138mpa. The results show that when the size of SiC powder is less than 0.6 μ m, it can be densified at 1950 ℃ even without any additives.