New vacuum sintering method

Vacuum hot pressing sintering
Hot press sintering applies axial pressure to the green body based on the traditional sintering method, so that the ceramics can obtain additional mechanical energy during the sintering process and promote the sintering densification process. The external stress during the sintering process promotes the creep of the crystal grains, allowing the ceramic to obtain a higher density in a shorter period of time. However, the external stress increases the interaction between the crystal grains during the sintering process, and small crystal grains easily aggregate and merge into large ones. The grain size of the sintered body is relatively large.
Vacuum high pressure sintering
Ordinary hot-press sintering often can only provide a pressure of tens of MPa, and cannot effectively reduce the sintering temperature, discharge gas and inhibit the growth of grains, so high-pressure sintering came into being. High-pressure sintering mostly uses mechanical multi-directional pressure, which can cause ceramics to be sintered under a pressure of more than 1GPa. Therefore, high-density ceramics can be obtained at a lower temperature and a shorter holding time. However, due to excessive pressure, the The equipment requirements are relatively high, so its application is subject to certain restrictions.
Microwave sintering
It has the advantages of high energy efficiency, no pollution, rapid overall heating, low sintering temperature, and uniform material microstructure. The overall heating method of microwave can make the ceramic body reach the sintering temperature quickly. The microwave radiation causes the crystal grains to vibrate with the electromagnetic wave frequency. The high-speed movement of the particles and the heat generated in the high-speed movement and mutual collision jointly promote the sintering of the ceramic material. Significantly improve sintering efficiency.
Spark plasma sintering
Spark plasma sintering has the characteristics of hot press sintering, and at the same time introduces the effect of electric field. Therefore, the sintering driving force not only comes from high temperature and external mechanical force, but also the effect of electric field and intergranular plasma, so it can greatly promote sintering. Using this method can not only effectively reduce the sintering temperature, significantly shorten the sintering time, but also reduce the grain size in the sintered body.
laser sintering
When the high-energy laser beam scans the sample, the irradiated area can quickly reach a very high temperature and locally generate a liquid phase to achieve the effect of liquid phase sintering, so the sintering process can be completed in a short time. However, the laser beam can only reach a certain depth on the sample and the temperature rises and falls quickly during the sintering process, which will lead to uneven sintering effects inside and outside the ceramic body and inability to eliminate stress, resulting in lower density and smaller grain size. Problems such as large size and many defects. In order to solve this kind of problem, low-energy laser can be used to scan the slurry coating layer by layer to prepare a pre-sintered body, and then calcined at high temperature to obtain high-performance ceramics.
The traditional process requires high sintering temperatures and long holding times and is difficult to achieve sintering densification, but it has unparalleled advantages in being non-selective to sintered samples.
Vacuum hot-press sintering, vacuum high-pressure sintering and discharge plasma sintering utilize the effects of external pressure and discharge local high temperature to achieve densification and sintering, while greatly shortening the sintering time and lowering the sintering temperature. However, these methods require external mechanical pressure and only require external mechanical pressure. Can sinter ceramics with simple shapes.
Microwave sintering not only has high sintering efficiency, but also can sinter ceramic materials with complex shapes. Although almost all ceramic materials can be sintered by adding microwave media, complex processes and equipment limitations severely restrict the industrialization progress of microwave sintering.
As an emerging sintering process, laser sintering is not yet mature. How to achieve sintering densification stably and how to suppress grain growth while densifying requires further exploration.

Learn More:

What Is Aluminum Vacuum Brazing

Titanium alloy vacuum brazing process

Why Switch To Brazing In A Vacuum Furnace