Introduction of ceramic hot isostatic pressing sintering

Hot-pressing sintering has many advantages, but because it is unidirectionally pressurized, the shape of the prepared sample is simple, generally sheet or ring. In addition, for the samples of non-equiaxed crystal system, the flaky or columnar grains are seriously oriented after hot pressing. The hot isostatic pressing sintering method combines the advantages of both the hot pressing method and the pressureless sintering method. It can not only improve the density, inhibit the grain growth, and improve the performance of the product like the hot pressing sintering method, but also can like the pressureless sintering method. It produces products with very complex shapes and avoids the grain orientation of non-equiaxed samples, which is an advanced ceramic sintering method.

The furnace cavity is often made into a column shape, and a high-pressure atmosphere can be passed through it. The gas is the pressure transmission medium, and the heating element is a resistance heating element. The pressure of the current high temperature isostatic pressing device can reach 200MPa, and the temperature can reach 2000C or higher. Since the gas is the pressure-bearing medium during HIP sintering, and the pores in the ceramic powder or green body are continuous, the sample must be encapsulated, otherwise the high-pressure gas will penetrate into the sample and the sample cannot be densified.

In addition to being used directly for sintering ceramic specimens, HIP can also be used to post-process samples that have undergone pressureless sintering to further increase sample density and eliminate harmful defects. Hot isostatic pressing, like hot pressing, has been successfully used for sintering or post-machining of various structural ceramics, such as zirconia ceramics, alumina ceramics, etc.!