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

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.

Evaluation of Functionalized Coatings for the Prevention of Ice Accretion by Using Icing Wind Tunnel Tests

“…This test methodology was based on previous works [25,42] but was adapted to this specific application. Some modifications such as temperature range, loading rate, and the geometry of the molds have been implemented in order to obtain more reliable and consistent results.…”

“…When these coatings are impregnated with heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane, SPH behavior is observed. Very recently Mora and collaborators have studied the behavior of quasicrystalline materials (QCMs) in icing conditions [42]. Some QCMs exhibit non-stick properties and are used for cookware with the advantage of scratch resistance.…”

Durability of Lubricated Icephobic Coatings under Multiple Icing/Deicing Cycles

“…This method was referred to as the flame spray process with hybrid feedstock injection [24]. Recently, several thermal spraying methods have been used to produce icephobic coatings, such as suspension plasma spray [26], high-velocity oxygen-fuel (HVOF) spray [27][28][29] and flame spray processes [30,31]. However, some of these technologies required additional post-treatments to render the surface water repellent [26,29].…”

Special Issue “Anti-Icing Coatings and Surfaces”

“…The problems related to ice adhesion on structures is a global annoyance which has caused and is still causing threat to industry and public safety in many parts of the world, including North American (USA, Canada), Asian (Japan, China) European and Scandinavian countries, as reflected by the research contributions in this Special Issue by authors from these countries who constantly strive to minimize its impacts [1][2][3][4][5][6][7][8][9][10]. World renowned experts have been addressing the ice adhesion issues with their advanced research and development and in the finding of advanced technologies to evaluate the adhesion phenomena, both theoretically and experimentally.…”

“…The ten contributions constituting this Special Issue are composed of the latest developments and the state of the art regarding ice adhesion, which are well elaborated for a wide range of readers, including research scientists, students and industrials, as well as the curious audience. These ten contributions originate from countries worldwide, namely, Canada (Quebec), Italy, Spain, China, Norway, Germany, Bulgaria and USA [1][2][3][4][5][6][7][8][9][10].…”