Hard Quasicrystalline Coatings Deposited by HVOF Thermal Spray to Reduce Ice Accretion in Aero-Structures Components

J. Mora,A. Agüero,R. Muelas,P. García

doi:10.3390/coatings10030290

J. Mora, A. Agüero + Show 2 more

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https://doi.org/10.3390/coatings10030290

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Abstract

Weather hazards, in particular icing conditions, are an important contributing factor in aviation accidents and incidents worldwide. Many different anti-icing strategies are currently being explored to find suitable long-lasting solutions, such as surface engineering, which can contribute to reduce ice accumulation. Quasicrystals (QCs) are metallic materials, but with similar properties to those of ceramic materials, such as low thermal and electrical conductivities, and high hardness. In particular, QCs that have low surface energy are commercially used as coatings to replace polytetrafluoroethylene (PTFE), also known as Teflon, on frying pans, as they do not scratch easily. PTFE exhibits excellent anti-wetting and anti-icing properties and therefore QCs appear as good candidates to be employed as ice-phobic coatings. Al-based QCs have been applied by High Velocity Oxyfuel (HVOF) thermal spray on typically used aeronautic materials, such as Ti and Al alloys, as well as steels. The coatings have been characterized and evaluated, including the measurement of hardness, roughness, wetting properties, ice accretion behavior in an icing wind tunnel (IWT), and ice adhesion by a double lap shear test. The coatings were studied, both as-deposited, as well as after grinding, in order to study the effect of the surface roughness and morphology on the ice accretion and adhesion properties. The QC coating was compared with PTFE and two polyurethane (PU)-based commercial paints, one of them known to have anti-icing properties, and the results indicate an ice accretion reduction relative to these two materials, and ice adhesion lower than bare AA6061-T6, or the PU paint in the ground version of one of the two QCs. Since the QC coatings are hard (GPa Vickers hardness > 5), a durable behavior is expected.

Highlights

Ice accretion over surfaces affects many different industrial fields, such as aeronautics [1], maritime [2], aero-generators [3], power lines [4], etc., causing reduction in efficiency, energy consumption due to the required measures to mitigate it, and most significantly important, safety risks.In particular, super-cooled water droplets present in clouds can result in the formation of an ice layer with a thickness of several millimeters in only 1 or 2 min on aircrafts
The QC coating was compared with PTFE and two polyurethane (PU)-based commercial paints, one of them known to have anti-icing properties, and the results indicate an ice accretion reduction relative to these two materials, and ice adhesion lower than bare AA6061-T6, or the PU paint in the ground version of one of the two QCs
QC coatings deposited by the High Velocity Oxyfuel (HVOF) thermal spray has been studied

Summary

Introduction

Super-cooled water droplets present in clouds can result in the formation of an ice layer with a thickness of several millimeters in only 1 or 2 min on aircrafts. This layer is enough to modify the aerodynamic behavior of the structures [5], or disrupt the navigation systems and sensors with catastrophic consequences [6]. A wide range of methods to avoid, or delay, ice accretion, and/or to release ice quickly once it has formed, are being explored These methods have been grouped into two categories:

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