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Characteristics of nFOG, an aerosol-based wet thin film coating technique

Harra, Juha; Tuominen, Mikko; Juuti, Paxton; Rissler, Jenny LU ; Koivuluoto, Heli; Haapanen, Janne; Niemelä-Anttonen, Henna; Stenroos, Christian; Teisala, Hannu and Lahti, Johanna, et al. (2018) In Journal of Coatings Technology Research 15(3). p.623-632
Abstract

An atmospheric pressure aerosol-based wet thin film coating technique called the nFOG is characterized and applied in polymer film coatings. In the nFOG, a fog of droplets is formed by two air-assist atomizers oriented toward each other inside a deposition chamber. The droplets settle gravitationally and deposit on a substrate, forming a wet film. In this study, the continuous deposition mode of the nFOG is explored. We determined the size distribution of water droplets inside the chamber in a wide side range of 0.1–100 µm and on the substrate using aerosol measurement instruments and optical microscopy, respectively. The droplet size distribution was found to be bimodal with droplets of approximately 30–50 µm contributing the most to... (More)

An atmospheric pressure aerosol-based wet thin film coating technique called the nFOG is characterized and applied in polymer film coatings. In the nFOG, a fog of droplets is formed by two air-assist atomizers oriented toward each other inside a deposition chamber. The droplets settle gravitationally and deposit on a substrate, forming a wet film. In this study, the continuous deposition mode of the nFOG is explored. We determined the size distribution of water droplets inside the chamber in a wide side range of 0.1–100 µm and on the substrate using aerosol measurement instruments and optical microscopy, respectively. The droplet size distribution was found to be bimodal with droplets of approximately 30–50 µm contributing the most to the mass of the formed wet film. The complementary measurement methods allow us to estimate the role of different droplet deposition mechanisms. The obtained results suggest that the deposition velocity of the droplets is lower than the calculated terminal settling velocity, likely due to the flow fields inside the chamber. Furthermore, the mass flux of the droplets onto the substrate is determined to be in the order of 1 g/m3s, corresponding to a wet film growth rate of 1 µm/s. Finally, the nFOG technique is demonstrated by preparing polymer films with thicknesses in the range of approximately 0.1–20 µm.

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Contribution to journal
publication status
published
subject
keywords
Aerosol measurement, Droplet size distribution, nFOG, Polymer film, Wet coating technique
in
Journal of Coatings Technology Research
volume
15
issue
3
pages
623 - 632
publisher
Springer
external identifiers
  • scopus:85045145179
ISSN
1547-0091
DOI
10.1007/s11998-017-0022-7
language
English
LU publication?
yes
id
34c41ee9-cf41-4ad4-81ae-3957e17299a1
date added to LUP
2018-04-20 15:31:04
date last changed
2019-05-17 10:56:20
@article{34c41ee9-cf41-4ad4-81ae-3957e17299a1,
  abstract     = {<p>An atmospheric pressure aerosol-based wet thin film coating technique called the nFOG is characterized and applied in polymer film coatings. In the nFOG, a fog of droplets is formed by two air-assist atomizers oriented toward each other inside a deposition chamber. The droplets settle gravitationally and deposit on a substrate, forming a wet film. In this study, the continuous deposition mode of the nFOG is explored. We determined the size distribution of water droplets inside the chamber in a wide side range of 0.1–100 µm and on the substrate using aerosol measurement instruments and optical microscopy, respectively. The droplet size distribution was found to be bimodal with droplets of approximately 30–50 µm contributing the most to the mass of the formed wet film. The complementary measurement methods allow us to estimate the role of different droplet deposition mechanisms. The obtained results suggest that the deposition velocity of the droplets is lower than the calculated terminal settling velocity, likely due to the flow fields inside the chamber. Furthermore, the mass flux of the droplets onto the substrate is determined to be in the order of 1 g/m<sup>3</sup>s, corresponding to a wet film growth rate of 1 µm/s. Finally, the nFOG technique is demonstrated by preparing polymer films with thicknesses in the range of approximately 0.1–20 µm.</p>},
  author       = {Harra, Juha and Tuominen, Mikko and Juuti, Paxton and Rissler, Jenny and Koivuluoto, Heli and Haapanen, Janne and Niemelä-Anttonen, Henna and Stenroos, Christian and Teisala, Hannu and Lahti, Johanna and Kuusipalo, Jurkka and Vuoristo, Petri and Mäkelä, Jyrki M.},
  issn         = {1547-0091},
  keyword      = {Aerosol measurement,Droplet size distribution,nFOG,Polymer film,Wet coating technique},
  language     = {eng},
  number       = {3},
  pages        = {623--632},
  publisher    = {Springer},
  series       = {Journal of Coatings Technology Research},
  title        = {Characteristics of nFOG, an aerosol-based wet thin film coating technique},
  url          = {http://dx.doi.org/10.1007/s11998-017-0022-7},
  volume       = {15},
  year         = {2018},
}