Aerospace and aviation coatings are generally used for protecting the structures and surfaces of the aircraft from harsh environments, varying temperature conditions, high pressure and providing drag reduction. However, conventional aerospace coatings suffer from significant mechanical, environmental and financial drawbacks, allowing new opportunities for thermal barrier, icephobic and protective nanocoatings in the sector.
Market drivers
Requirements in this sector such as resistance to extreme temperatures, extreme climates, corrosion, abrasion and wear of engine parts have resulted in an increased demand for more reliable, high performance coatings. Aviation, especially military aviation, suffers high maintenance costs which can be alleviated with the use of anti-corrosion, thermal barrier and drag reducing nanocoatings.
Performance benefits
Advantages of using nanocoatings in aerospace and aviation include reduced carbon footprint, fewer cleaning and maintenance costs, protection against corrosion and erosion and reduced ice accretion. Nanocoatings add special characteristics to aircraft frames and interior and engine parts and component surfaces including:
• self-cleaning;
• super-hydrophobicity;
• low densities;
• improved hardness;
• enhanced drag;
• wear and corrosion resistance;
• improvement in fuel efficiency;
• resistance to both dynamic & static failure mechanisms;
• conductivity;
• anti-icing;
• improved thermal barrier performance and flame retardancy.
Nanocoatings allow for fuel-burn savings through drag reduction. The efficiency of aircraft is severely compromised by the prevalence of turbulent drag and icing. The high level of turbulent skin-friction occurring, e.g. on the surface of an aircraft, is responsible for excess fuel consumption and increased carbon emissions.
The environmental, political, and economic pressure to improve fuel efficiency and reduce carbon emissions associated with transportation means that reducing turbulent skin-friction drag is a pressing engineering problem. Superhydrophobic nanostructured top aircraft coatings not only exhibit improved aerodynamic efficiency but at the same time they prevent icing on the aircraft. Nanocoatings can also facilitate crack healing on aircraft, resulting in improved high-temperature, strength and creep resistance.
Commercialization
A number of aerospace & aviation companies and agencies already utilize nanocoatings. Multilayer structure, temperatures resistant, thermal shock, corrosive and erosive wear-resistant nanocoatings are increasing in application in turboengines, extending their service life considerably. Easyjet has used a nanocoating developed by TripleO to improve drag resistance on their aircraft.
SAAB (www.saab.com) has filed a patent to use graphene for de-icing airplanes. The graphene layer would be embedded in a heating jacket covering the aircraft.
CG2 NanoCoatings, Inc. (www.cg2nanocoatings.com) has developed a process to utilize nanoscale properties by first functionalizing nanoparticles and then incorporating them into a base material (polymers, metals, ceramics or composites) for anti-icing coatings. Nanovere (www.nanovere.com) also produces nanocoatings to significantly reduce ice adhesion, de-icing maintenance costs, and reduce the coefficient of wind and water drag resistance, thereby decreasing the cost of jet fuel.
Tesla NanoCoatings (www.teslanano.com) produces corrosion control coatings with fullerene carbon nanotube cathodic protection of metal to the aerospace/military, petrochemical, transportation, marine, and industrial markets. Powdermet (www.powdermetinc.com) has partnered with the U.S. Navy to provide a solution to contamination issues in spherical plain airframe bearings using advanced coatings that have already been commercialized through Abakan subsidiary MesoCoat. These nanocomposite cermet materials have applications across the transportation, energy, military, construction and other sectors for reducing friction and extending the life of, or eliminating the need for lubricants, in highly stressed systems. EnvAerospace (www.envaerospace.com) uses NPS-PVD (Physical Vapour Deposition) to produce a wide range of wear-resistant, anti-corrosive, thin ultra-hard films applicable to aerospace applications.
