Different Approaches to Low-Wettable Materials for Freezing Environments: Design, Performance and Durability

Giulio Boveri,Mariarosa Raimondo,Federico Veronesi,Alessandro Corozzi

doi:10.3390/coatings11010077

Abstract

Ice nucleation and accretion leads to multiple problems such as freezing of the streets which can cause traffic collisions or people injuries, and collapse of high voltage power lines leading to black-out and icing of aircraft components, causing major aeronautic accidents. The most widespread strategies for the removal of accumulated ice layers result in most cases being expensive, time-consuming and hazardous for the environment. In this work we present the design of hydrophobic hybrid inorganic-organic coatings via Lotus leaf-like and slippery liquid infused porous surfaces (SLIPS) approaches with reduced, lasting wetting performance in cold environments. Static and dynamic wetting behavior was evaluated at room and sub-zero temperatures. The main target was the selection of the most suitable design approaches and formulations of coatings to be applied on metals or alloys when the contact time between the droplet and the material surface has to be minimized. In the temperature range from −10 to 0 °C, we report evidence of a stable hydrophobicity and a low water contact angle hysteresis (below 15°) of all the SLIPS developed. The surfaces’ ability to keep their wetting performance unchanged during the freeze/and frost/thaw durability cycles stood out as a key issue for further development at larger scale.

Highlights

The interaction between water in many different forms—either liquid or solid like dry or wet snow, ice, frost, rime or combinations thereof—and a solid surface at a subzero temperature is a complex matter to investigate, depending on many material-related parameters, e.g., surface chemical composition and texturing, and environmental conditions such as temperature, humidity, wind velocity, etc.The formation and the following accretion of different forms of solid water on structural installations, facilities and infrastructures, aeronautic components, telecommunication systems and so on represents a huge problem in cold regions or under specific operational contexts
We explored a different approach to liquid repellency, as per the so-called slippery liquid infused porous surfaces (SLIPS) approach
We added low surface tension lubricants—different types of fluorinated KrytoxTM GPL and a silicone oil—with different viscosities and chemical compositions to explore their different behaviors when infused in the hybrid-coated surfaces

Summary

Introduction

The interaction between water in many different forms—either liquid or solid like dry or wet snow, ice, frost, rime or combinations thereof—and a solid surface at a subzero temperature is a complex matter to investigate, depending on many material-related parameters, e.g., surface chemical composition and texturing, and environmental conditions such as temperature, humidity, wind velocity, etc.The formation and the following accretion of different forms of solid water on structural installations, facilities and infrastructures, aeronautic components, telecommunication systems and so on represents a huge problem in cold regions or under specific operational contexts. In order to mitigate such phenomena, the most widespread and effective strategies for the removal of accumulated ice layers are based on the Joule effect, mechanical removal, electro-impulse methods or application of de-icing fluids [1,2,3,4] These traditional procedures are in most cases expensive, time-consuming and hazardous for the environment. In this framework, many authors refer to the generally called anti-icing materials and technologies as a solution to prevent or delay nucleation, adhesion and accumulation of dry/wet snow, frost, rime, ice, or their combination, according to the specific environmental conditions

Methods

Results

Conclusion