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  • 1.  Effect of Moisture Content on Powder Flowability in Thermal spraying

    TSS Board Vice President
    Posted 05-23-2022 07:59
    Dear Thermal Spray Community,

    Are there any studies or papers written on the effect of moisture content on powder flowability or coating properties? Most of us keep the feedstock
    powders in a dryer before spraying to prevent flowability or coating problems. Is there a percent of moisture that affects flowability or coating properties?

    Cheers!

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    Rogerio Lima, PhD
    Senior Research Officer
    National Research Council of Canada
    ASM Thermal Spray Society (TSS) Vice President
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  • 2.  RE: Effect of Moisture Content on Powder Flowability in Thermal spraying

    Posted 05-24-2022 11:32
    Edited by Milad Rad 05-24-2022 11:36
    Thank you, Rogerio, for this great question.  Given I am also curious about finding any possible connection between the relative humidity (RH) and the flowability of feedstock powders, I found the following two papers that might be of interest to you. It is known that flow deterioration definitely occurs at elevated relative humidity levels and this is because of the increased capillary bridge formation. Also, it is believed that the structure and the size distribution of the powder particles have a great role to play. However, the sad part is that the impact of RH level and flowability is noticeably different from one case (powder composition, structure, and size distribution) to another and you should find a paper that has described this relation preferably in a graph for the particular powder that is of interest to you.

    I will be thankful to anyone who could contribute to this discussion and provide a more detailed response.

    1.
    Stanford, M.K., DellaCorte, C. Effects of humidity on the flow characteristics of a composite plasma spray powder. J Therm Spray Tech 15, 33–36 (2006). https://doi.org/10.1361/105996306X92550
    2. Vikram Karde, Chinmay Ghoroi, Fine powder flow under humid environmental conditions from the perspective of surface energy, International Journal of Pharmaceutics, Volume 485, Issues 1–2, 2015, Pages 192-201, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2015.03.021


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    Milad Rad
    Assistant Professor
    University of Southern Indiana
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  • 3.  RE: Effect of Moisture Content on Powder Flowability in Thermal spraying

    TSS Board Vice President
    Posted 05-24-2022 12:13
    Thanks Milad,

    Your feedback is highly appreciated. We all face these humidity power issues in thermal spraying from time-to-time, and it is very good to know that we have references that address this problem.

    Hopefully we will have additional feedback.

    Thanks again!

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    Rogerio Lima, PhD
    Senior Research Officer
    National Research Council of Canada
    ASM Thermal Spray Society (TSS) Vice President
    ------------------------------

    Thermal Spray Accepted Practices - Order Today


  • 4.  RE: Effect of Moisture Content on Powder Flowability in Thermal spraying

    Posted 05-24-2022 14:07
    Thank you, Rogerio. It is always a great pleasure reading your helpful posts and this time, this great technical question. I cannot wait to see more technical discussions on this page.

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    Milad Rad
    Assistant Professor
    University of Southern Indiana
    Evansville IN
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