A Brief Introduction Of 10 Sintering Processes For Alumina Ceramics-8 9

8. The two-step sintering process

The two-step sintering process involves heating the sample to a specific temperature (T1) to remove the subcritical pores from the billet, and then dropping to a lower temperature (T2) to make the billet compact.In the low-temperature sintering stage of two-step sintering method, grain boundary diffusion is mainly used in this stage because the activation energy required by grain boundary migration is higher than that required by grain boundary diffusion.Therefore, in the second stage of two-step sintering, the billet becomes denser, but the grains do not grow too fast.In the low-temperature sintering stage of the two-step sintering method, the prerequisite for the complete densification of the green body is that the pores in the green body gradually become closed pores during the shrinkage of the green body.

9.Microwave two - step sintering

Two-step sintering can be carried out in traditional sintering furnace with low equipment cost and strong application value.However, two-step sintering is a relatively slow sintering process due to the need for a long time at the second temperature point.Microwave heating usually has the advantages of integral heating and rapid heating. Few studies combine microwave heating with two-step heating.However, microwave heating can reduce sintering temperature and sintering time, which is beneficial to further grain refinement and effectively shorten the production cycle of two-step method.