Besides the basic kinetic of crystal growth, the densification of ceramic is driven by the different chemical potential of atoms between the material source and sink, which is usually governed by the capillary pressure. When the compacts are closely packed, there are still many fine pores between the particles. The capillary pressure across a curved interface (P) and the difference in vacancy concentration between the surface and interior of the particles (c) are two key driving forces for mass-transport and pores elimination. Based on the Young-Laplace equation: