Vacuum Sintering of Tungsten Carbide Products

Vacuum sintering means that powder, powder compacts, or other forms of materials are heated at a suitable temperature in a vacuum environment to achieve the connection between particles through atomic migration. Sintering is to make porous powder compacts that have alloys with certain structures and properties.

Cemented carbide vacuum sintering is a process of sintering under 101325Pa. Sintering under vacuum conditions greatly reduces the hindering effect of adsorbed gas on the powder surface and gas in the closed pores on densification. Sintering is beneficial to the diffusion process and densification and can avoid the reaction between the metal and some elements in the atmosphere during the sintering process. Significantly improve the wet-ability of the liquid binder phase and the hard metal phase, but vacuum sintering should pay attention to prevent the evaporation loss of cobalt.

Cemented carbide vacuum sintering can generally be divided into four stages. There are plasticizer removal stage, pre-sintering stage, high-temperature sintering stage, and cooling stage.

The advantages of vacuum sintering of cemented carbide are:

1. Reduce the pollution of products caused by harmful gases in the environment. For example, it is extremely difficult to reach the dew point of minus 40 ℃ for the water content of hydrogen generated by electrolysis, but it is not difficult to obtain such a degree of vacuum;

2. Vacuum is the most ideal inert gas. When other restorative and inert gases are not suitable, or for materials that are prone to decarburization and carburization, vacuum sintering can be used;

3. Vacuum can improve the wet-ability of liquid phase sintering, which is beneficial to shrinkage and improve the structure of cemented carbide;

4. Vacuum helps to remove impurities or oxides such as Si, Al, Mg, and purifies materials;

5. Vacuum is beneficial to reduce adsorbed gas (residual gas in pores and reaction gas products) and has an obvious effect on promoting shrinkage in the later stage of sintering.

From an economic point of view, although the vacuum sintering equipment has a large investment and a low output per furnace, the power consumption is low, so the cost of maintaining the vacuum is far lower than the cost of the preparation environment. In the liquid phase of sintering under vacuum, the volatilization loss of the binder metal is also an important issue, which not only changes and affects the final composition and structure of the alloy but also hinders the sintering process itself.

Cemented carbide production is a rigorous process. ZZBETTER takes every production detail seriously, strictly controls the quality of cemented carbide products, and provides solutions for harsh working conditions.

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