Durable Icephobic Coating for Aluminum Substrate
Abstract
Development of durable icephobic coating and reduction of ice accumulation on the product surfaces has proven to be a challenging task in the past decade. Considering the challenges posted during ice storms and existing limitations to the state of the art, development of durable icephobic coating which can provide low ice adhesion strength and less ice weight increase is a critical milestone for industries and research communities. To obtain durable icephobic coating, high temperature and weather resistance Fluoro-Ethylene-Alkyl-Vinyl-Ether (FEVE) binder was selected to design a smooth and superhydrophobic coatings. These coatings were benchmarked against commercially available silicone epoxy and superhydrophobic coatings and validated its surface roughness, surface wettability and icephobic performance such as ice adhesion strength and ice accumulation. To evaluate coatings thermal durability, targeting power transmission line application, these coatings were exposed to extreme thermal ageing conditions (200 oC for 60 days) and retention of icephobic performance were measured. Though, commercial coatings have provided better icephobicity at unaged condition, after high temperature heat ageing these coatings icephobic performance were deteriorated significantly. However, FEVE based coating had retained its surface characteristics and icephobic properties after aggressive thermal ageing. Addition to developing icephobic coating, creating experimental understating of icephobic performance such as, the correlation between ice adhesion strength and coating material properties also would give a great scientific knowledge and guidance to the product designers. Hence, establishing big-picture icephobic understanding can provide valuable insights to material design choices for an application, when usage of specific material or manufacturing method is not possible. For example, certain applications retaining superhydrophobic surface for longer duration would be challenging or using low modulus material is not feasible or applying highly smooth surface with zero roughness is not at manufacturing. To map-out this design space for icephobic coating application, silicone-based coating material were selected, since silicone coating material has the flexibility to tune its properties and readily available in different modulus range as well. Silicone coatings were chosen from low modulus to higher modulus (8 psi to 28 psi) and its surface wetting properties were engineered as hydrophilic and superhydrophobic range from hydrophobic range. Also surface roughness were created using sand paper which selected with standard grit sizes such as 3000 GS, 300 GS and 30 GS. These silicone coated test panels with different mechanical properties, surface roughness and contact angles were evaluated and measured changes in ice adhesion strength. To validate ice weight increase by ice accumulation, automated ice accumulation test set-up was customized and used for icephobic performance validation. The experiment results suggest that at the lower coating modulus, roughness does not significantly affect the ice adhesion strength as compare to higher modulus coatings. Superhydrophobic coating has low ice adhesion strength across the coating modulus and roughness ranges. Additionally, superhydrophobic coatings had less ice accumulation as compare to smooth silicone coatings. Roughness plays a critical role in high modulus hydrophobic coatings, whereas smooth silicone surface performed relatively better as compare to rough surfaces.
Degree
Ph.D.
Advisors
Howarter, Purdue University.
Subject Area
Marketing|Polymer chemistry
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