TY - THES ID - 134578575 TI - Experimental investigation on the formation of ice/surface interphases AU - Snels, Laurens AU - Seveno, David AU - Wevers, Martine AU - KU Leuven. Faculteit Ingenieurswetenschappen. Opleiding Master of Materials Engineering (Leuven) PY - 2022 PB - Leuven KU Leuven. Faculteit Ingenieurswetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:134578575 AB - The formation and accumulation of ice on surfaces causes failures of industrial devices and facilities as well as domestic appliances. Solving these problems often requires energy-intensive and environmentally unfriendly de-icing methods. In order to eliminate the need for de-icing, passive hydrophobic/icephobic surfaces have been developed in recent years. Icephobic surfaces could be described as surfaces with low ice adhesion, enabling naturally present forces such as gravity or aerodynamic drag to remove the ice layer. Furthermore, a good icephobic surface should minimize ice accretion on the surface as well. Unfortunately, the reliability and durability of currently available icephobic surfaces are extremely limited since our understanding of the physics of icing is incomplete. Designing durable icephobic surfaces remains highly challenging and is currently unresolved. Besides, the complex phase change phenomena occurring at the water-substrate interface during freezing are still not clear, mainly due to a lack of characterization techniques to investigate an optically non-accessible interface: as an example, the mechanism for crack initiation and propagation, which is underpinning ice release from a surface, is poorly understood. As such, novel strategies should be developed that allow to better understand the mechanisms controlling the icing processes and provide new insights into the ice-surface interface. This Master Thesis introduces freezing X-ray Computed Tomography (XCT) as a novel characterization technique. The addition of an in-situ cooling stage, which was developed in-house, paves the way to explore an uncharted territory of icephobicity. While XCT has already been used to study the wettability of, for example, textiles and polymers, without the need for peripheral equipment within the system. Performing XCT in a temperature-controlled environment below 0°C is, however, still very uncommon. In most studies, the focus has only been on the ice entity itself, but, the ice-surface interface has not been thoroughly considered. Freezing XCT can drastically improve the way interfaces between supposedly icephobic surfaces and ice are characterized. Using freezing XCT on a surface with a frozen droplet, information on the three-dimensional shape, interface and internal structure (porosity) can be obtained, both qualitatively and quantitatively. The preliminary results illustrate that ice porosity is surface dependent. Currently, however, there is a gap in the state-of-the-art of anti- and de-icing techniques with regards to ice porosity. This is likely due to the lack of a technique that allows 3D quantitative analysis of porosity and the added complexity of taking porosity into account while modelling. In recent years, the interest in ice porosity and its effects is gradually increasing, indicating that porosity could be of great interest for various applications. Currently, it is shown that porosity influences the mechanical, optical, aerodynamic, and thermal properties of ice and could potentially be used to restore the Cassie-Baxter state, hence the importance of characterizing porosity to obtain a better understanding of the underlying mechanisms controlling ice adhesion. It will not only lead to a more comprehensive and fundamental view on icing but also to the development of novel ways to engineer icephobic coatings. XCT is expected to play a key role by characterizing the internal microstructure of ice droplets. ER -