Three Methods Of Sintering Silicon Carbide Ceramics

1) No pressure sintering
In 1974, GE company in the United States attempted to add a small amount of B and C to high-purity beta-SIC fine powder, and successfully obtained high-density SiC ceramics at 2020°C by using the pressure-free sintering process. The process has become the most important method for preparing SiC ceramics.

Now, some researchers have added Y2O3 and AI2O3 to submicron SiC powder to realize the dense sintering of SiC at the temperature of 1850°C to 2000C.Because of the low specific force of sintering temperature, there are obviously refined micro-inelegant structure, so its strength and toughness are greatly improved.

2) Hot-pressed sintering
In the mid-1950s, Norton company in the United States began to study the impact of metal additives such as Ni, Cr, B, Al and Fe on SiC hot-pressed sintering.The results show that De and AI are the most effective additives to promote the densification of SiC.Some people use AI2O3 as additive to successfully realize the densification of SiC through hot-pressing sintering process, and think that its mechanism is liquid phase sintering.Some people also used B4C, B or B and C, AI2O3 and C, AI2O3 and Y2O3, Be, B4C and C as micro-additives, and successfully obtained dense SiC ceramics by hot-pressed sintering.

(3)Hot isostatic sintering
In recent years, in order to further improve the mechanical properties of SiC ceramics, many researchers have studied the thermal isostatic pressure process of SiC ceramics, using B and C as additives and using the thermal isostatic pressure sintering process to successfully obtain high-density SiC sintered bodies at 1900°C. Further through this process, the densification of SiC ceramics without additives was successfully achieved at the pressure of 2000°C and 138MPa.The whole the results show that when the particle size of SiC powder is less than 0.6 um, it can be densified at 1950°C by hot isostatic sintering without any additives.

Learn more: High Vacuum Sintering Furnace