Cordierite glass (3 samples)

Because complete sample should be ground to < 15µm, a grinding in suspension is required. Therefore, we added 1ml of isopropyl alcohol (IPA) to maintain a motor oil like slurry.

By dry grinding, sample can only be ground to a fineness of d50 < 20µm. Afterwards, interacting forces between fine particles will become bigger as their own g-force. Those fine particles tend to stick together and will only become compressed to clusters. These compressed clusters will contain bigger particles (usually up to 60-120µm) which will not be ground any further.

To avoid overpressure, we ground the sample in steps of 5 minutes, followed by a programmed pausing time of 10 minutes. After several cycles, the outside temperature of the bowl should be checked (remain below 70°C); grinding time or programmed pausing time might be readjusted afterwards. This is counting for all further grinding trials too.

Within 15 minutes of grinding, the complete sample has been ground to < 15µm. Fineness has been checked by optical microscopy.

Comments given in result 1 also use to count in this trial.

As shown in this result, by longer grinding time, fineness will become improved. It is also possible to change ball diameter to e.g. 1,5mm Ø for faster and further improvement.

Final fineness has been determined by optical microscopy.

Comments given in result 1 also use to count in this trial.

Instead of zirconium oxide, hardmetal tungsten carbide has been chosen for this grinding trial. Hardmetal tungsten carbide has a much higher density instead of zirconium oxide. For this, we are guessing that an equal grinding result will be found much faster.

After 10 minutes of grinding of sample No. 2, a fineness of < 20µm has been achieved. Longer grinding time is required to achieve desired fineness (see result 4).

Fineness has been checked by optical microscopy.

Comments given in result 1 also use to count in this trial.

Sample of result 3 has been ground for additional 5 minutes. Afterwards, no particle > 10 µm has been found.

Final fineness has been determined by optical microscopy.

Comments given in result 1 also use to count in this trial.

Instead of zirconium oxide or hardmetal tungsten carbide, silicon nitride has been chosen for this grinding trial.

After 15 minutes of grinding of sample No. 3, a fineness of < 25µm has been achieved. Longer grinding time is required to achieve desired fineness (see result 6).

Fineness has been checked by optical microscopy.

Comments given in result 1 also use to count in this trial.

After totally 30 minutes of grinding of sample No. 3, a fineness of < 15µm has been achieved. Desired endfineness has been reached.

Fineness has been checked by optical microscopy.