TSS Membership Community

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!

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

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


------------------------------
Milad Rad
Assistant Professor
University of Southern Indiana
------------------------------

Original Message:
Sent: 05-23-2022 07:58
From: Rogerio Lima
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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!

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

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!

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

Original Message:
Sent: 05-24-2022 11:32
From: Milad Rad
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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


------------------------------
Milad Rad
Assistant Professor
University of Southern Indiana

Original Message:
Sent: 05-23-2022 07:58
From: Rogerio Lima
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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!

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

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.

------------------------------
Milad Rad
Assistant Professor
University of Southern Indiana
Evansville IN
------------------------------

Original Message:
Sent: 05-24-2022 12:12
From: Rogerio Lima
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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!

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

Original Message:
Sent: 05-24-2022 11:32
From: Milad Rad
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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


------------------------------
Milad Rad
Assistant Professor
University of Southern Indiana

Original Message:
Sent: 05-23-2022 07:58
From: Rogerio Lima
Subject: Effect of Moisture Content on Powder Flowability in Thermal spraying

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!

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