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

Research output: Contribution to journalArticleScientificpeer-review

Details

Original languageEnglish
Pages (from-to)623-632
Number of pages10
JournalJournal of Coatings Technology Research
Volume15
Issue number3
Early online date1 Feb 2018
DOIs
Publication statusPublished - May 2018
Publication typeA1 Journal article-refereed

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 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.

Keywords

  • Aerosol measurement, Droplet size distribution, nFOG, Polymer film, Wet coating technique

Publication forum classification

Field of science, Statistics Finland