Infiltration
is kind of process that uses the metal or alloy which has lower melting point than
the product to fill in the pores of products in molten state. For tungsten
copper electrode, copper solution has lower melting point and it fill in the
porous tungsten skeleton, which has excellent density and strength so that
tungsten copper material has better properties, such as thermal conductivity,
electric conductivity and high hardness.
The
process is: Tungsten powder (W) + shaping agent (or adds Cu-induced powder) → tungsten skeleton (suppressing + degreasing +
sintering) → copper infiltration (Cu)
→ after treatment. And the
most research focus on:
1.
Powder granularity
2.
Tungsten skeleton
3.
Infiltration process
4.
After treatment.
Powder
granularity: It stresses that tungsten powder granularity has an effect on
tungsten copper electrode and other properties. Generally, the higher sintering
temperature, the larger average granularity and the better strength of tungsten
skeleton. However, if the granularity of tungsten powder exceeds a certain
degree, the contact area among tungsten powder will be reduced and the tungsten
powder can not be necking, which decreases the strength and hardness of
tungsten skeleton and material.Some scientists do some researches about tungsten
powder granularity and volume fraction effects on density of tungsten copper
electrode, they thought it depends on original grain size of tungsten powder
and this effect will decrease by the increasing temperature of sintering
temperature.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvVo83pSWqQK3c4Eq7O1yDTtQaqn41OQxUaXFVSwjgWMMigmiaqO_n9zoR26-Ou_Y9eGI9KvzvbtVcEbbfkaSKSsxmS1Z5HF27TlX8rLjxbyUH6e31rQ4AQniuQ999kU_PjWxFSVJSt5Jc/s320/tungsten-copper-0421.jpg)
Besides,
mixed with light of Cu-induced powder will improve the corrosion ratio and the
efficiency. Chinese scholars use 0.8-3.0μm tungsten powder for mixing, the result shows that despite small
average granularity of tungsten powder, the density of sintering blank is still
lower and the micro-structure is maldistributed.Viewed from tungsten skeleton, it is a key of high
density tungsten copper electrode manufacturing by infiltration. Due to
tungsten (W) has high melting point, high hardness and low contraction, it is
difficult to be machining and densifying, which becomes the major part of
scholars study. The study of tungsten skeleton can be divided into two types,
one is the shaping properties of tungsten skeleton, and the other is the
sintering properties of tungsten skeleton.