De-icing innovation for aircraft also tackles corrosion De-icing aircraft is a critical safety procedure that takes up time and money. New corrosion-resistant coatings have been developed and could help aviation achieve operational efficiencies, and benefit other industrial sectors as well. Transport and Mobility © Jaromir Chalabala, Shutterstock At temperatures below zero, flying becomes hazardous. This is in part due to the risk of ice forming on wings and other mechanical sections – this can interfere with safe take-offs and affect the normal operation of a plane. For example, the extra weight can significantly increase drag, leading to difficult handling conditions and higher energy consumption. As a result, de-icing remains a vitally important element of plane maintenance. The ERICE project focused on addressing the challenge of de-icing on a specific part of a plane – the air cycle machine (ACM). This critical system provides temperature-controlled oxygen to the cabin, and consists of a refrigeration unit and a network of pipes, including external exhaust pipes. “The problem of icing on these pipes is similar to the challenge of icing on wings and other parts of the plane,” notes ERICE project coordinator Fabiola Brusciotti from Tecnalia in Spain. “The difference is that ice particles or supercooled water droplets hitting the inside and outside of exhaust tubes, through which cold air flows, can cause surface erosion, besides corrosion.” Superhydrophobic solutions At present, the de-icing of ACM pipes usually consists of applying high temperatures onto these pipe surfaces. This is expensive and energy-consuming. The ERICE project sought to address this by developing new de-icing techniques to ensure that ice doesn’t attach itself to the surface in the first place. “We wanted to develop and test surface treatments with properties resistant to ice adhesion and corrosion, and to ensure that any ice that does attach itself falls off easily,” explains Brusciotti. The project team began by screening existing superhydrophobic solutions for inner pipe surfaces, and then creating new hydrophobic treatments for different types of substrates (aluminium alloys and PEEK, a thermoplastic material). Superhydrophobic and erosion-resistant surfaces were developed through trialling innovative surface texturing techniques, in combination with hybrid sol-gel technology. All chemicals used fully comply with the EU’s REACH chemical regulations. “Our coating solutions were trialled on a test rig at Cranfield University in the United Kingdom, which was specifically designed to reproduce the conditions of ice formation in ACMs,” adds Brusciotti. By situating this rig in a classic ice tunnel – with cold temperatures, wind and ice-forming water spray – the project team was able to compare the performance of their coating with current de-icing methods. Pioneering protective coatings These tests demonstrated the potential of ERICE’s pioneering coatings. “We were able to show that our solutions work well at removing ice and tackling erosion,” says Brusciotti. “This isn’t always easy, because ice behaves differently depending on its formation conditions.” Pilot testing of project innovations in real-life situations is scheduled for this summer. ERICE’s coating technology could be transferable to other ice-sensitive environments, including other parts of the plane such as wings. “We have also been contacted by industries that face icing issues, including operators of wind turbines and high-tension electrical cables,” adds Brusciotti. One advantage is that the coatings are not only hydrophobic but also ‘omniphobic’, a term that describes a surface that repels virtually any liquid. This could open the door to more applications such as anti-fingerprint surfaces that can be easily cleaned, as well as antimicrobial surfaces. “In this project we looked specifically into ice, and at the challenge of de-icing ACMs,” says Brusciotti. “But from a market point of view – and with a little modification – this concept could be opened up to other markets.” Keywords ERICE, icing, plane, ACM, PEEK, hydrophobic, omniphobic, erosion, antimicrobial
