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Thread: Flowing of Ceramic Powders

  1. #1
    Dr. Alan Nappa - Alberti Guest

    Flowing of ceramic powders!!

    Good Morning!
    I'm evaluating the possibility to apply ceramic powders (SiO2+Al2O3+feldspars+clays) mixed along with pigments (transition metal oxides) through silicon engraved rollers (or silk printing screens) on to flat superficies, as glass or sintherized tiles. I've tried the classical modified fumed silica gel and fumed allumina. The appearance of the overall is quite fine, inside a bottle the solids seem "liquid as water" but when I start applying by screen (or roller) they form agglomerates and tend to stick together. Any suggestion? Thanks a lot!!

  2. Just a thought, but have you considered the electrostatic charging tendancy for the powders? It may be worth assessing.

    Regards

    Richard Farnish
    The Wolfson Centre for Bulk Solids Handling Technology, Univ.Greenwich, London, UK
    http://www.bulksolids.com

  3. #3
    Dr. Alan Nappa - Alberti Guest
    Originally posted by R_Farnish
    Just a thought, but have you considered the electrostatic charging tendancy for the powders? It may be worth assessing.

    Regards

    Richard Farnish
    The Wolfson Centre for Bulk Solids Handling Technology, Univ.Greenwich, London, UK
    http://www.bulksolids.com
    You got the point! In fact it was the same thought of mine. Actually, I have no clue to overcome it. I searched additives to reduce or eliminate this tendancy, but all I got were liquid ones, nothing in solid state. Do you experienced something similar before?

    THANKS A LOT!

    Alan

  4. Electro-static charging is quite a tricky problem to overcome. You already have considered some options, but you should also look at the handling technique and materials used in the construction of the handling/dispensing equipment. It is known that some materials of construction will exacerbate charging.

    If this operation is important to your company, perhaps we could set up a collaborative research project?

    There is a section on electro-static charging in "Cake Formation in Particulate Systems" by Edward J Griffith ((ISBN 0-89573-748-5), that might be of interest to you.

    Please feel free to e-mail me if the idea of research appeals (we may be able to get EC funding - depending upon your company and location).

    Regards

    Richard Farnish
    mailto: r.j.farnish@gre.ac.uk
    http://www.bulksolids.com

  5. Even flow without material bonding

    Hello Dr Alan, I was interested in reading of your problem and the various comments made to date. Have you considered the employment of Acoustic Cleaners which use sound waves to prevent 'material to material' and 'material to structure' bonding from occuring. at the same time they can enhance material flow

    If this thread is of interest, either have a look at our web site on www.primasonics.com or e-mail me on sound@primasonics.com

    It may just provide you with the answer!

  6. #6
    schulenberg Guest
    Hello, Dr Alan.
    We are selling diatomaceous earth ("Diamol") from Denmark as a flowability or anti-caking-agent. This material bonds humidity in its capillaries and leads to a better flowability. If it is not a humidity problem Diamol sticks very good on all surfaces and leads also to a better flowability.

    If you are interested to test it don't hesitate to contact me again for a sample or further information.

    Regars
    Roland Schulenberg
    Franz Bertram GmbH, Manangement
    Amsinckstr. 45 - D-20097 Hamburg
    Tel.: +49(0)40/237 30 3-0, Fax: -17
    Email: rs@franz-bertram.de - www.franz-bertram.de

  7. #7
    Marcello - Italy Guest

    Flowability Model

    Some months ago I have request informations about models to describe the flowability of powders.

    In particular I was interested about mathematical equations that links size distribution with this parameters.

    Recently I have applied DOE technique with differents materials and size distribution and I have obtained mathematical models that can determine the flowability of the system in function of size distribution and morphology of particles.

    The approch works in a promising way.

    Best regards

    Marcello Romagnoli
    University of Modena and Reggio Emilia - Italy

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