Anti-Icing Functional Biphilic Surfaces And Functionalized Multiscale Metal Organic Framework-Based Coatings

Official URL: https://risc01.sabanciuniv.edu/record=b3205841

Ice formation is a major challenge for engineering systems. In this dissertation, it is aimed to provide understanding about fundamentals of ice formation, ice accumulation and de-icing, to identify the governing mechanisms and to develop surfaces and coatings for antiicing applications. In this thesis, a functionalized metal-organic framework (ZIF-8) based micro-nanosubnano scale coating (SHMC) with CA>172°, rolling angle <5°, and CAH<3° was developed. The coating was applied to metallic substrates by the practical spray coating method. Superimposed nanoparticles and porous structure of ZIF-8 created a surface morphology containing a significant number of airpockets. This thesis proves the superiority of SHMC over current approaches. Static and dynamic anti-icing behavior of SHMC was vigorously investigated. A fractal theory-based model of water contact angle was adapted to reveal its non-wetting mechanism. SHMC extended the icing time by at least 300% and maintained its superhydrophobicity for more than 30 icing/deicing cycles. The generated capillary pressure ranges within the multiscale coating were studied. The three-phase contact line characteristics were assessed. A significant reduction in heat transfer during the droplet contact time was obtained with SHMC. Furthermore, this thesis provides valuable information about de-icing behavior of biphilic surfaces. The results indicated that the biphilic surface consisting of superhydrophobic islands with the diameter of D=500 μm on a hydrophilic substrate having the superhydrophovity ratio of 19.62% was capable of complete passive cleaning due to the Laplace pressure gradient generated by this specific surface design. Furthermore, as the superhydrophobicity ratio increased, more delay in ice formation and accumulation occurred. The results show that the choice of the surface design is a compromise between its icing and de-icing behavior.