Polishing suspension Cerium dioxide

Present sample got delivered as a slurry. For an optimum grinding result, we recommend adding a proper amount of solvent to achieve a motor oil like viscosity. Too low viscosity as present might cause higher abrasion on grinding balls and bowl. Too high viscosity will slow down the grinding balls (with a limited grinding result).

For particles of a start size of 50 µm, we recommend using grinding balls of 2 mm Ø to be sure all sample will get ground properly. With smaller grinding balls, it might be possible that largest pieces still stay intact.

To avoid over pressure, we ground the sample in steps of 3 minutes, followed by a programmed pausing time of 9 minutes. After several cycles, the outside temperature of the bowl should be checked (remain below 80°C); grinding time or programmed pausing time might be readjusted afterwards. This is counting for all further grinding trials in suspension.

After 15 minutes of grinding, we checked the present fineness of particles with our Laser Particle Sizer ANALYSETTE 22 NanoTec. All particles should be < 10 µm; it is still possible to proceed grinding to achieve a better grinding result (see result 2).

We proceeded grinding for further 15 minutes and checked the particle size distribution afterwards.

Fraunhofer calculation model will be imprecise when majority of particles will be < 1 µm. For this we set a refractive index of 1,54 and used Mie calculation. When proper Mie parameters can be provided, a more precise result can be recalculated.

Quantity of particles rose during the grinding process. Therefore, more specific surface need to be moistened and viscosity will get more and more pasty. We would recommend adding more of solvent or water to grind with an optimum viscosity.

Because it is not allowed, we are guessing that only a limited grinding success will occur with this viscosity (see result 3).

We proceeded grinding the suspension for a total grinding time of 60 minutes. Afterwards, the sample is very creamy.

We found a d90 already < 690 nm at this moment. Because of present viscosity, we don’t expect that a longer grinding will improve the result significantly. With the present viscosity, we also don’t recommend using smaller grinding balls. For the smallest available grinding balls of 0,1 mm Ø, a motor oil like viscosity should be set.

We interrupted the grinding process at this point and packed the sample.