Icephobic and Anticorrosion Coatings Deposited by Electrospinning on Aluminum Alloys for Aerospace Applications.

Adrián Vicente,Francisco Carreño,Pedro J. Rivero,Julio Mora,Paloma García,Rafael Rodríguez,José F. Palacio

doi:10.3390/polym13234164

Abstract

Anti-icing or passive strategies have undergone a remarkable growth in importance as a complement for the de-icing approaches or active methods. As a result, many efforts for developing icephobic surfaces have been mostly dedicated to apply superhydrophobic coatings. Recently, a different type of ice-repellent structure based on slippery liquid-infused porous surfaces (SLIPS) has attracted increasing attention for being a simple and effective passive ice protection in a wide range of application areas, especially for the prevention of ice formation on aircrafts. In this work, the electrospinning technique has been used for the deposition of PVDF-HFP coatings on samples of the aeronautical alloy AA7075 by using a thickness control system based on the identification of the proper combination of process parameters such as the flow rate and applied voltage. In addition, the influence of the experimental conditions on the nanofiber properties is evaluated in terms of surface morphology, wettability, corrosion resistance, and optical transmittance. The experimental results showed an improvement in the micro/nanoscale structure, which optimizes the superhydrophobic and anticorrosive behavior due to the air trapped inside the nanotextured surface. In addition, once the best coating was selected, centrifugal ice adhesion tests (CAT) were carried out for two types of icing conditions (glaze and rime) simulated in an ice wind tunnel (IWT) on both as-deposited and liquid-infused coatings (SLIPs). The liquid-infused coatings showed a low water adhesion (low contact angle hysteresis) and low ice adhesion strength, reducing the ice adhesion four times with respect to PTFE (a well-known low-ice-adhesion material used as a reference).

Highlights

Ice accretion on surfaces presents a serious challenge from an operational, economical, and safety perspective especially in cold climates
The electrospun coated samples were immersed into the lubricant silicon oil for 1 h, and afterwards, all samples were kept in a 45◦ tilted plate overnight to get rid of excess oil, obtaining slippery liquid porous surfaces
Five operational points in the “Cone jet” electrospinning mode area have been correctly identified by controlling the flow rate and applied voltage, as input parameters, for a fixed PVDF-HFP polymeric concentration

Summary

Introduction

Ice accretion on surfaces presents a serious challenge from an operational, economical, and safety perspective especially in cold climates. AA7075-T6 aluminum alloy flat samples (AL-USTOCK, Vitoria, Spain) with a final dimension of 75 mm of length, 50 mm of width, and 2 mm of thickness were polished with a roughness less than (Sa = 0.8 μm; Ra = 0.7 μm) and cleaned with acetone This specific aluminum alloy has been selected as the reference substrate to test the corrosion resistance due to it being one of the most important alloys used in aeronautical applications where high mechanical properties and corrosion resistance are need [40,41]. For all the other tests, the coatings were (a) directly deposited onto aluminum alloy substrates and (b) onto a aluminum alloy samples with a fresh layer of sprayed glue (SUPERGEN spray mounts glue, Ceys) intended to increase the adhesion of the coating to the substrate [42]

Electrospinning Procedure

Characterization Techniques

Wettability Properties

Conclusions