Sintering

Sintering of ceramic materials is the method involving consolidation of ceramic powder particles by heating the “green” compact part to a high temperature below the melting point, when the material of the separate particles difuse to the neghbouring powder particles.

In the process, time, temperature, pressure, atmosphere, and heating/cooling rates are important variables, which need to be optimized such that the desired degree of bonding in between the particles is formed, thereby achieving maximum densification along with improved physical and mechanical properties. Usually at higher sintering temperatures, faster and irregular grain growth occurs, while at lower sintering temperatures with smaller sintering times, more number of pores exists at the grain boundary, which impede the grain boundary movement and hence grain growth.

Hence in order for reach the adequate dense, ceramics must be sintered to high temperatures for specific periods of time in gas or electric kilns. Typical firing temperatures using periodic or tunel kilns for alumina and zirconia is between 1550 °C - 1750 °C.