Nano-enabled anti-icing surfaces and coatings - Superhydrophobicity and icephobicity characterization of fouling-release coatings
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Anti-icing and icephobic materials have been topics of many researches due to the challenges that icing poses. Arctic regions are also gaining interest due to its resource potentials. In this thesis, different commercial and experimental fouling-release coatings are examined. The goal is to confirm the results from the project work of 2014, which indicated that foul-release coatings also have good ice release properties. Testing for icephobicity using ice is both time consuming and cost ineffective. Another goal is therefore to find a correlation to icephobicity with other parameters that can be tested at room temperature.15 fouling-release coatings were acquired from several companies and one anti-icing coating. Ice adhesion measurements were taken using a medium scale interfacial indentation testing method created by a former master student working in the group. Water adhesion was measured using a tensiometer. Roughness values are acquired by AFM and profilometer. Coating thicknesses were measured by profilometer and elastic moduli measurements were performed using a triboindenter. The contact angle data were obtained using a goniometer. Selected coatings were also characterized using the S(T)EM. Results show that foul-release coatings that have low elastic modulus below 6 MPa and low water adhesion force values under 0.3 mN had low ice adhesion stress. The coating with best ice removal result had an average ice adhesion stress value of 6.88 kPa. In comparison, all the anti-icing coatings had average values above 100 kPa. For rigid substrates a positive linear correlation between ice adhesion and water adhesion force is observed. An attempt to normalize the values is also carried out using the extension or height of the water droplet at the position where the maximum water adhesion force is detected. Elastic substrates also have a positive linear pattern with water adhesion values. However, the correlation is observed within groups with more or less the same chemistry. A suggestion is that for elastic coatings, ice adhesion is also dependent of elastic modulus and thickness. Therefore, an attempt is performed at correlating the ice adhesion with the work of adhesion which takes into consideration the parameters, elastic modulus and thickness. No direct correlation with ice adhesion was observed for contact angles and surface roughness.