| 1. |
- Harra, Juha, et al.
(författare)
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Characteristics of nFOG, an aerosol-based wet thin film coating technique
- 2018
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Ingår i: JCT Research. - : Springer Science and Business Media LLC. - 1547-0091 .- 2168-8028 .- 1935-3804. ; 15:3, s. 623-632
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Niemelä-Anttonen, Henna, et al.
(författare)
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Icephobicity of Slippery Liquid Infused Porous Surfaces under Multiple Freeze–Thaw and Ice Accretion–Detachment Cycles
- 2018
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Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:20
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Tidskriftsartikel (refereegranskat)abstract
- Surface engineering can be used to prevent ice accumulation and adhesion in environments that deal with icing problems. One recent engineering approach, slippery liquid infused porous surfaces (SLIPS), comprises a smooth and slippery lubricating surface, where lubricant is trapped within the pores of a solid material to repel various substances, such as water and ice. However, it remains unclear whether the slippery surfaces retain their icephobic characteristics under the impact of supercooled water droplets or repeated freezing and melting cycles. Here, the icephobic properties of SLIPS are evaluated under multiple droplet freeze–thaw and ice accretion–detachment cycles and compared to hydrophobic and superhydrophobic surfaces. The experiments are designed to mimic real environmental conditions, thus, the icephobicity is investigated in icing wind tunnel, where ice accretion occurs through the impact of supercooled water droplets. The adhesion of ice remained extremely low, <10 kPa, which is four times lower than ice adhesion onto smooth fluoropolymer surfaces, even after repeated ice accretion–detachment cycles. Moreover, cyclic droplet freeze–thaw experiments provide insight into the effects of temperature cycling on SLIPS wettability, showing stable wetting performance. The results suggest liquid infused porous surfaces as a potential solution to icephobicity under challenging and variating environmental conditions.
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