Ice adhesion
Ice adhesion - ice sticking to surface
Water droplet can either stick to the icing surface or bounce of it on collision. A supercooled droplet will not bounce, it will stick to the surface regardless of whether it is dry or wet. Supercooled droplets freeze immediately, and other droplets either freeze or join the water layer on the surface. Conversely, snow particles do not stick so easily. Factors like impact velocity, humidity and temperature, and particle features like wetness affect the sticking efficiency. Dry particles bounce more easily if there is no liquid layer, and lower impact speeds increase sticking efficiency.
Impact velocity of the particle influences the ice type. The water droplet’s time to freeze on the surface is important because droplet moves on it. Impact velocity increasing means that the sticking efficiency decreases.
Ice accretion and adhesion is also affected by material properties and an eventual coating.
Heat conduction of the surface material also affects ice accretion during precipitation icing.
Wetting behavior of the icing surface affects ice adhesion. Wetting behavior determines how the water droplets act upon contact with the surface. Droplet movement on the surface increases icephobicity. Hydrophobicity increases the droplet movement, which can reduce icing. Because of this, superhydrophobic surfaces can delay ice formation. Droplets movement on the surface is dependent on the contact angle. Studies have shown, that when the contact angle grows, the ice adhesion strength decreases.
More on this topic: ice adhesion test (CAT)
Examples of ice adhesion values
When comparing materials or surface designs with each other, it is important to understand that they all have different wettability, surface free energy, surface morphology, liquid-solid interaction, surface chemistry, heterogeneity, and liquid absorption/retention etc.properties that make them unique. Even within the same material group, variations can be found. The data in the figure has been measured in Tampere University by using the same test setups, the IWIT and the CAT, with mixed glaze ice type. The figure illustrates how different samples within the same surface design or material group can have altering ice adhesion values. [2]
References
- ↑ Aavindraa. Wikimedia commons. Creative Commons Zero, Public Domain Dedication.
- ↑ 2.0 2.1 Icephobic Performance of Different Surface Designs and Materials. Henna Niemelä-Anttonen, Jarkko Kiilakoski, Petri Vuoristo, Heli Koivuluoto Materials Science and Environmental Engineering, Tampere University, Finland. IWAIS 2019 - Reykjavík, June 23 – 28. Proceedings – Int. Workshop on Atmospheric Icing of Structures.
- ↑ Niklas Kandelin: Icing Factors Affecting Railway Traffic Master of Science Thesis Tampere University Master’s Degree Programme, Materials Science October 2021. Online. https://www.icingcenter.eu/wp-content/uploads/2021/11/KandelinNiklas.pdf
- ↑ Ingvaldsen, K. (2017) Atmospheric icing in a changing climate: Impact of higher boundary temperatures on simulations of atmospheric ice accretion on structures during the 2015-2016 icing winter in West-Norway.
- ↑ Li, G. (2018). Fundamentals of icing and common strategies for designing biomimetic anti-icing surfaces. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 6(28), 13549–13581.
- ↑ Meuler, A. J. et al. (2010) Relationships between water wettability and ice adhesion., ACS applied materials & interfaces, Vol. 2, No. 11, 2010, pp. 3100– 10.
- ↑ Stenroos, C. (2015) Properties of icephobic surfaces in different icing conditions.