There are basically two methods of producing nano-scale particles: the “Bottom-Up” technique involves synthesizing the particles from atoms and molecules. With the “Top-Down” method the particles are reduced to nanometer size by grinding. A suitable tool for this method is a planetary ball mill, such as RETSCH’s PM 100, PM 200 or PM 400, which provides the necessary energy input.
The common rules for size reduction to micron size do not apply for the nano-scale; with decreasing particle size, electrostatic and even molecular interactions increase, leading to particle agglomerations which cannot be reduced any further in size. For this reason, the grinding process has to be carried out in a liquid medium (= colloidal grinding) which disperses the particles as much as possible.
For nano-grinding in a ball mill, the grinding jar and balls have to be of a very abrasion-resistant material, such as zirconium oxide, to minimize contamination of the sample material by abrasion. Factors like the choice of dispersion medium or grinding ball size have a crucial influence on the success of the process. Generally, small ball diameters < Ø 3 mm and grinding times of several hours are beneficial for the production of nano-particles as substantially more energy and a greater surface are required than for dry grinding in the micron range. RETSCH provides grinding balls as small as Ø 0.1 mm for ultra-fine grinding. Thanks to various safety features, it is perfectly possible to run the RETSCH ball mills unsupervised for many hours.
RETSCH Planetary Ball Mills:
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powerful and quick grinding down to nano range
- automatic grinding chamber ventilation
- programmable starting time
- power failure backup ensures storage of remaining grinding time
- reproducible results due to energy and speed control
- 10 SOPs can be stored
- perfect stability on lab bench thanks to FFCS technology
- suitable for long-term trials and continuous use
- 2 different grinding modes (dry and wet)
- wide range of materials for contamination free grinding
Find out more at www.retsch.com/pm
Retsch is the leading solution provider for neutral-to-analysis sample preparation and characterization of solids. On the basis of more than 90 years of experience RETSCH develops innovative size reduction and sieving equipment which is characterized by excellent performance, operating convenience, safety and a long lifetime.
Retsch GmbH
Ute Vedder, Marketing
Rheinische Str. 36, 42781 Haan, Germany
Telefon: +49 (0) 21 29/55 61-155
Telefax: +49 (0) 21 29/55 61-213
E-Mail: [email protected].