Planetary Ball Milling
Contents
General remarks
Selection of the milling media
Which balls to use? Material, size, quantity? Which jar to use? How much filling can go in? Which liquid to use?
Stoichiometry considerations
Weighting in the powder and milling balls
Milling procedure
Separating the slurry
Use a very clean sieve (sieves are a source of contamination) and a wide and clean glass beaker to separate the slurry and balls. The finer the balls are, the more slurry and powder remains in the balls. To a ceratin amount, it can be drained with additional liquid. If the balls are smaller than 2mm, it is best to use a technical sieve with 150µm mesh. Using a funnel and a glas bottle with vacuum adapter all with appropriate sealing will ease the procedure and minimize the amount of solvent needed to separate the slurry.
Drying
The glass beaker is covered with aluminium foil with a number (10-30) holes to allow evaporation of the liquid. The beaker then can be dried in a laboratory oven at a temperature below the boiling temperature of the liquid. Boiling should be prevented as it can cause contamination of the oven. If the liquid is flammable, the drying stove should be explosion protected and the lab well-vented. Drying usually takes at least one day.
Sieving
As after drying, the powder is usually agglomerated, it should be sieved once it is completely dry. Avoid sieving slightly humid powder.
