What is the conventional sintering method for alumina ceramics
Jul 20, 2024
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What is the conventional sintering method for alumina ceramics? Conventional sintering methods cannot meet the requirements for preparing transparent alumina ceramics. Commonly used sintering methods for preparing transparent ceramics are: a atmosphere and vacuum sintering, b hot isostatic pressing sintering, c discharge plasma sintering, etc.
What is the conventional sintering method for alumina ceramics
1. Atmosphere and vacuum sintering
Alumina ceramics prepared by atmospheric pressure sintering usually have 1~3% residual pores, and sintering in vacuum or atmosphere can produce a large number of oxygen vacancies in the alumina blank, accelerate the diffusion of O2-, and speed up the densification rate of the blank, which can make it easier to remove the residual pores.
2. Hot Isostatic Pressing
Hot isostatic pressing (HIP) is a high temperature and high pressure production technology. The heating temperature can reach 2000℃. By using high pressure inert gas or nitrogen in a closed container as the pressure transmission medium, its working pressure can reach more than 200MPa. Under the combined action of high temperature and high pressure, the closed gas holes that are difficult to eliminate under normal pressure sintering can be eliminated, and submicron alumina ceramics with high transparency can be prepared. Due to the small grain size of transparent alumina ceramics prepared by this method, the mechanical properties of the ceramics are very excellent.
3. Spark Plasma Sintering
Spark plasma sintering (SPS) is to load the raw material powder into a mold made of graphite and other materials, and use the upper and lower die punches and powered electrodes to apply a specific sintering power supply and pressing pressure to the raw material powder. The sintering process is completed through discharge activation, thermoplastic deformation and cooling. Since SPS can sinter quickly and can achieve the densification of fine ceramic structures at a lower temperature, it has been widely used in the preparation of transparent alumina ceramics in recent years.