The primary task of developing the new warm compaction technology is to select or develop a suitable polymer additive, which can be used as a binder / lubricant. For the tungsten carbide powder, the selected polymer needs certain characteristics, such as low vitrification temperature, easily soluble in volatilization agent and so on. Main entry modes of polymer are dry mixing, wet mixing and so on.

 

1, Requirements of Polymer

1.1, Lower vitrification temperature (about 150 ℃). Otherwise, it will bring difficulties to the preparation process.

1.2, Easy to dissolve in volatile solvent.

1.3, It is easy to form a lubricating film on the surface of the alloy powder or to form a transfer film during the process of pressing, that is, the lubrication between the two is good.

1.4, When cracking, a lot of gas should be avoided, and new holes are produced in the powder metallurgy parts.

1.5, It can prevent or slow down the oxidation of alloy powder.

1.6, Ecology-Friendly.

 

 

2, Tungsten Carbide Polymer

Tungsten carbide powder is the hard and brittle powder. According to the densification mechanism of the rearrangement of particles in the process of compaction, a proper number of elastic polymers must be added in the powder. In order to improve bonding strength between powders, viscous polymer containing polar groups should also be added to the powder, so as to maximize mechanical contact and chemical connection of polymer to powder.

 

Of course, some components can be added to the powder to achieve the purpose of lubrication and plasticization. It can be seen that the design of forming agent is one of the key technologies in order to obtain excellent temperature pressure pressing performance and ensure that the tungsten carbide powder has enough strength.

 

3, Polymerization and Entry Mode

3.1, Dry mixing of polymer powder and alloy powder.

3.2, Mixing the polymer and the alloy powder. At the same time, heat up to the melting point Tf.

3.3, After the polymer is dissolved in the volatile solvent, the polymer is added to the alloy powder in the form of wet mixing.