We`re seeking for someone with an access to air classification unit to process / sieve fine metallic powders? We`re willing to pay for this service and/or we offer authorship in the papers which arose from this research.
Hi Martin,
such laboratory systems are very rare and often deliver a questionable and poorly reproducible result. What kind of powder do you want to classify (particle size, composition)? and in what quantities? Maybe you can get to your desired goal better with a normal screening machine. I have experience with it and can possibly recommend a screening machine.
Hi Vadim,
we have different powders in our mind. But we aim to start with fine gas atomized specific metal powder, whereas the d10, d50, and d90 powder particle size values are 1.35, 3.21 and 7.45 µm, respectively. We want to screen the powder fraction 0.5-1.5 um. I have 25 kg of the feedstock powder. Normal screening machine operates down to 20um (gravitation) or 10um (air sucking assisted). I have them both.
Separating the fraction smaller than 1.5 microns from the powder smaller than 8 microns is next to impossible in a dry state. Agglomeration of such powders is so strong that the agglomerates can only be broken down into a liquid. It doesn't work with an air classifier.
Martin Balog Vadim Verlotski
I'd agree that getting out this fine fraction is close to impossible. By normal definition these would be tightly-bound aggregates (caused by van der Waals attraction and solid-solid diffusion) rather than loosely bound agglomerates. There's a lower limit (Google 'comminution limit') also that sets the lowest possible sized material in a powder. For example, there are no free, independent, discrete particles < 100 nm (i.e. 'nano') in a powder. See (registration required):
Dispersion and nanotechnology
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat
Adhesion and cohesion
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W180725AdhesionCohesion
Based on discussion with producer Netzsch LabCompactPlus enables such classification. It features high energy "mill" option, which is being used to separate fine satellites eg for Ti 3D printing purpose. Maybe I rather be looking in industry rather than academia.
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