Laboratuvar değirmenleri, öğütücüler ve kırıcılar birincil ve ince boyut küçültme için

AAS, NIR, ICP veya XRF gibi kimyasal ve fiziksel analitik metotları için tam olarak homojen hale getirilmiş numune hazırlamak çok önemlidir. Güvenilir ve doğru analiz yapmanın garantisi tekrarlanabilir numune ha

Why use a laboratory mill for grinding?

Comminution of solids or bulk materials is necessary when the material has a grain size that is too coarse for subsequent processes, such as analysis, division, mixing or further processing, and/or the sample is too inhomogeneous, so that the small portion used for analysis is not representative of the entire laboratory sample. Analyses are necessary for quality assurance, for example in production monitoring or incoming goods inspection. These include spectroscopic and chromatographic methods. Since product properties are often influenced by the particle size (e.g. extraction, filtration or absorption capacity), size reduction with a laboratory mill is also essential for the development of new products and production processes.

Required fineness

A frequent requirement is: “Pulverize finely”. However, the term “powder” is not clear. Washing powder, coffee powder and baking powder are bulk products that all claim the term “powder” but have very different particle size distributions. Another frequent requirement is to grind the sample “as fine as possible” using a laboratory mill. However, this always requires a high energy input and a lot of time. Time and energy also mean costs in laboratory operations. A more effective approach is: Not as fine as possible, but as fine as necessary! It is important that the sample material is of analytical fineness. The required analytical finenesses vary, depending on the subsequent analytical method or the subsequent process.

Is comminution an art?

The art of crushing consists of preparing the sample with a laboratory mill in such a way that a representative individual sample is obtained that has a homogeneous analysis fineness. When selecting a suitable laboratory mill and grinding set, it must be ensured that the characteristics of the sample to be determined (e.g. moisture content, heavy metal content, etc.) are not changed during the entire preparation process. In addition to a precise knowledge of the equipment, this also requires experience in processing various materials. Contact Retsch for non-binding advice on equipment and applications.

通过声波显微镜研究纯金属钛粉和钛粉以及铁-铜合金的纳米晶体机械性能

Determination of mechanical properties of nanocrystalline materials by means of acoustic microscopy : application of pure elements (Fe and Ti) and alloys (Fe-Cu)

Nanostructured materials are distinguished from conventional polycrystalline materials by their extremely fine crystallite sizes. Because of the extremely small dimension of the grains, a large fraction of the atoms in these materials is located in the grain boundaries. This confers special attributes to this class of new materials.
The elastic modulus of a material is related to the atomic binding forces and characterizes the elastic properties of the material under loading. Young modulus can be measured by sound velocity (Korn et al 1988, Kobelev et al, 1993, Sanders et al 1999), tensile testing (Korn et al 1988, Nieman et al 1991, Wong et al, 1994, Sakai et al 1999 ), nanoindentation (Mayo et al 1992, Mayo et al 1990, Fougere et al 1995) in nc-metals and nc-ceramics upon compacted powders.
Compared to conventional metal, the ratio E/E0 (where E and E0 represent Young’s modulus of nc-metal and conventional metal respectively) is very variable, usually weak, due to important residual porosity which is often not measured.
The objective of the present study is to determine mechanical properties and especially elastic modulus for nc-metals (Fe and Ti) and nc-alloys (Fe-Cu). Dense nanomaterials are necessary involving consolidation of small samples with high pressure.

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