Warm Compacting Process Impact on Tungsten Copper Density (2/2)

In addition, it is necessary that consider the glass transition temperature of the temperature and pressure of the main component of the binder, temperature and pressure temperature closer to the glass transition temperature, the better the viscous flow of the binder can form a good lubricating film on the particle surface, effectively reducing inter particle internal friction and external particles and mold wall friction, effectively increasing the density of tungsten and copper compacts. When temperature and pressure temperature exceeds the glass transition temperature of the binder, the binder near the melting point, viscosity decreases, lubrication is no longer obvious, friction coefficient rises, effectively suppress power drops down so that the compact density decreases.

Theoretically, for pressing pressure, the density of material by PM is increasing with the increasing pressing pressure. However, increasing the pressure is having some limitations, first of all it is necessary to subject to the applicable conditions of tolerance and mold equipment. Besides, the pressure should be chose according to the impact on tungsten copper compacts. By contrast green density at room temperature and pressure different pressing force, both of which are rising as the pressing pressure, green density increases. But at the same compaction pressure units, the density of tungsten copper green by warm compacting process is higher than the density of tungsten-copper compacts by cold compacting process. This is due to the molding temperature and pressure present in the adhesive film surface of the particles can effectively reduce the particle relative displacement resistance when pressing the powder particles are better able to transmit pressure, increasing the effective pressing pressure, which will help increase the density of compacts.

Furthermore, in the process of warm compacting process, the yield strength and hardening rate of metal powder grains decrease, which increases the plastic deformation of powder particles and is beneficial for improving the density of green. Concerning powder compacting law, many experts and scholars propose some famous equation of repression, combined with the requirements of production equipment as well as the relative performance of tungsten copper required, thereby rational use of temperature and pressure molding process to improve its green density.

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