The principle of action of ceramic sintering additives

Sintering is the process of heating the raw material powder to produce particle bonding, and after material migration to produce strength in the powder body and lead to densification and recrystallization. The reason why common ceramic powders are difficult to sinter is that they have high lattice energy, stable crystal structure, and require high activity for mass diffusion, i.e., high sintering activation energy, and therefore require higher temperatures.

In order to promote sintering, on the one hand, we can consider activating the lattice and lowering the sintering activation energy, mainly through doping to destroy the stable lattice structure and make defects in the crystal or cause lattice distortion; on the other hand, we can consider accelerating the diffusion process, mainly through generating the liquid phase in the system, which generates particle bonding and fills the pores by surface tension, and using the "dissolution-precipitation" process. In the other direction, we can consider the accelerated diffusion process, mainly by generating the liquid phase in the system, which produces particle adhesion and fills the pores by surface tension, while using the "dissolution-precipitation" mechanism to promote sintering by gradually depositing the dissolved small grains on the surface of large grains through liquid-phase mass transfer.