Wettability, water droplet dynamics and freezing on irregularly roughened stainless-steel surfaces for ice protection application

• Main Author: Shi, Kewei
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2023
• Subjects: Arctic
• Online Access: https://research.library.mun.ca/15835/; https://research.library.mun.ca/15835/3/converted.pdf

In the Arctic and other cold environments, ice can jeopardize local infrastructure, hinder field operations, damage buildings, offshore and ship superstructures and threaten life and property. Ice protection techniques are essential for equipment, structures, and personnel in these environments. Passive techniques rely on the physical properties of the target surface to dispose of ice or prevent ice build-up without any required external energy source. As a passive ice protection technology, (super)hydrophobic metallic surfaces can significantly delay the water droplet impact and freezing process. However, hydrophobic surfaces are not always icephobic. The droplet impact dynamics and freezing process on irregularly roughened (super)hydrophobic metal surfaces have not been fully understood. Previous experimental studies have limited the impact and freezing of water droplets on cold surfaces at room temperature. Most experimental and modelling investigations have also been limited to separately studying droplet impingement and freezing processes. Hence, this study aims to investigate dynamic wetting behaviours and freezing processes coupled with the impact dynamics of a water droplet on irregularly roughened metal surfaces experimentally and analytically. To achieve this, irregularly roughened stainless-steel surfaces are fabricated by applying sandblasting, Zinc electrodeposition, stearic acid coating, and their combinations to receive various water wettability. The combination of electrodeposition and sandblasting can significantly increase the static contact angle from 91° ± 6° to 151° ± 2°, and these techniques can be applied on an industrial scale. Surface dynamic wetting characterization illustrates the challenges of understanding the wetting dynamics on irregularly roughened surfaces, including dynamic contact angles and pinning that affect the sliding behaviour on inclined surfaces. These effects result in a poor correlation between the measured dynamic contact angles and the observed critical sliding ...