tungsten powder grained, agglomerated

A grinding with bowl and balls made of stainless steel use to be plausible. After 3 minutes of dry grinding, a d50 < 7,7 µm (see particle size analysis on Laser Particle Sizer ANALYSETTE 22 MicroTec plus on separate page) has been achieved. After 3 minutes of grinding, outside temperature of the bowl use to be about 40 °C.

Because sample is not sticking to bowl or balls yet, longer dry grinding times are possible (see result 2).

After a total dry grinding time of 5 minutes, a d50 < 7,3 µm (see particle size analysis on Laser Particle Sizer ANALYSETTE 22 MicroTec plus on separate page) has been achieved. After 5 minutes of grinding, outside temperature of the bowl use to be about 50 °C.

Because sample is only sticking lightly to bowl or balls yet, longer dry grinding times are still possible (see result 3).

After 20 minutes of grinding, outside of the bowl reached a temperature of ~ 118 °C. Sample starts sticking a stronger to bowl and balls.

This uses to happen after the majority of particles reached a fineness of < 20-30 µm. Interacting forces between fine ground particles will become bigger as their own g-force. Therefore, particles will stick to each other and become compressed by the used grinding balls. These clusters of particles also contain bigger particles which will not be ground any further.

We detected a fineness of d50 < 6,31 µm which is bigger as desired fineness. To reach a better fineness, only a grinding in suspension is recommended.