The Process of Sintering Tungsten Carbide

As we all know, tungsten carbide is one of the hardest materials applied in modern industry. To make a tungsten carbide production, it has to experience a range of industrial procedures, like powder mixing, wet milling, spray drying, pressing, sintering, and quality check. During the sintering, the volume of the cemented carbide will shrink by half. This article is to determine what happened to tungsten carbide during sintering.

During the sintering, there are four stages that tungsten carbide must experience. They are:

1. Removal of the molding agent and pre-burning stage;

2. Solid-phase sintering stage;

3. Liquid-phase sintering stage;

4. Cooling stage.

1. Removal of the molding agent and pre-burning stage;

In this process, the temperature should be increased gradually, and this stage happens below 1800℃. As the temperature increases, the moisture, gas, and residual solvent in the pressed tungsten carbide gradually evaporate. The molding agent will increase the carbon content of the sintering cemented carbide. In different sintering, the increase of carbide content is different. The contact stress between powder particles is also gradually eliminated during the increase in temperature.

2. Solid-phase sintering stage

As the temperature is slowly increasing, the sintering continues. This stage occurs between 1800℃ and the eutectic temperature. The so-called eutectic temperature refers to the lowest temperature at which a liquid can exist in this system. This stage will continue based on the last stage. The plastic flow increases and the sintered body shrinks significantly. At this moment, the volume of tungsten carbide shrinks obviously.

3. Liquid phase sintering stage

At this stage, the temperature rises until it reaches the highest temperature in the sintering process, the sintering temperature. When the liquid phase appears on the tungsten carbide, shrinkage completes quickly. Due to the surface tension of the liquid phase, the powder particles approach each other, and the pores in the particles are gradually filled with the liquid phase.

4. Cooling stage

After sintering, the cemented carbide can be removed from the sintering furnace and cooled to room temperature. Some factories will use the waste heat in the sintering furnace for new thermal utilization. At this point, as the temperature drops, the final microstructure of the alloy is formed.

Sintering is a very rigorous process, and zzbetter can provide you with high-quality tungsten carbide. If you are interested in tungsten carbide products and want more information and details, you can CONTACT US by phone or mail at the left, or SEND US MAIL at the bottom of the page.