Dear Researcher
1. We are using Fritsch Planetary ball milling for milling of metal powders. I am still confused about the pre- cleaning and post-cleaning of vials and balls for efficient milling to avoid contamination.
we are using Tungsten carbide vials (250 CC) and balls (dia 10 mm)
2. What is the minimum sample volume to be used in 250 CC vial at 10: 1 BPR ratio
kindly share your thoughts
1. Here is a tip: After you thoroughly clean the vial and balls (wash them, then clean them with acetone or whatever you find more appropriate), then mill a small amount of the target powder and discard the powder, and clean the vial and balls again with acetone. Now the contamination for the next milling powder will be minimal,
2. Think of minimum amount as the amount you can recover from the vials/balls, also think if that minimum amount will be evenly distributed in the volume for milling with balls (for example if the amount is so small it will stick in the very corner of the vial and balls can not reach it for milling, then you need more amount of powder).
Also you said BPR is 10:1, so theoretically the minimum amount of powder will be when you use 1 ball and 1/10 powder, so here you have your answer.
Dear Dhana Sekaran,
If you would like to use the same vial already used for some other material, then the recommended cleaning procedure is to use fine grained sand with saw dust in the same proportion. After that you can go for the sacrificial running what Dr. Mkhitar (in tip1) was suggesting.
For the second question: The recommended extent of filling of container/vial with powder+balls coould not cover more than 50% of the vial volume. This gives the balls and powder particles can move freely to undergo good collision/impact with themselves resulting in good mechanical milling/alloying.
Ref: C.Suryanarayana, Mechanical milling and alloying
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