Tungsten Copper Sintering Technologies Comparison (1/2)

There are many kinds of tungsten copper sintering technologies, such as conventional infiltration, mixed-pressing, pressure sintering and new SPS (Spark Plasma Sintering), etc, which have their own advantages and disadvantages. Next, we analyze these different sintering technologies by the principle and the applications. First of all, infiltration, which is called melt immersion, is the most widely used in tungsten copper products currently. It is obtained by adding a small amount of tungsten powder or copper powder compacts made of tungsten powder and tungsten and copper infiltrated compacts stacked together, and thereafter sintered at a temperature above the melting point of copper and under reducing atmosphere or vacuum.

In the process of sintering, copper in a molten state to rely on capillary action infiltrated tungsten skeleton, two sintering and infiltration step can also be performed separately. Infiltration has many advantages, such as high density, excellent sintering properties and electrical and thermal conductivity, good arc ablation resistance. But liquid copper barely rely on capillary forces infiltrated tungsten skeleton, this will lead to coarse and uneven distribution of copper particles sintered tungsten particles at high temperatures easily grew up together. In addition, after infiltration machined to remove excess copper and will increase costs and reduce the yield.

Mixed - pressing sintering process is one of the most conventional powder metallurgy, which basic process is preparation →ball milling → compacting →sintering. Sintering can be also divided into two parts, one is solid phase sintering (temperature lower than the melting point of Cu), the other is liquid phase sintering (temperature higher than the melting point of Cu). Since the solid solubility in the liquid phase W Cu is small, the material can not be conveyed by dissolution and precipitation particles rounded manner, and tungsten and copper infiltration is poor, it is difficult to achieve densification.

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