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Synthesis of Advanced top Nano-coatings with improved Aerodynamic and De-icing behavior

Final Report Summary - SANAD (Synthesis of Advanced top Nano-coatings with improved Aerodynamic and De-icing behavior)

Duration of the project: 48 months
Start date of the project: January 1st 2013

1. Objectives
The efficiency of modern transportation 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, societal, and economic pressure to improve fuel efficiency and reduce carbon emissions associated with transportation denotes that reducing turbulent skin-friction drag is a pressing engineering problem.

SANAD project is dealing with these issues by developing superhydrophobic nanostructured top coatings, which do not only exhibit improved aerodynamic efficiency but at the same time they prevent icing on the aircraft. The nanostructured coatings were based on metal oxides or nanostructured carbon (carbon nanotubes or graphene oxide).
The scientific targets included the synthesis and chemical modification of nanoparticles that will be employed for the formulation of novel composite coatings, based on suitable resins. The structure and topology of the developed coatings were analyzed. Furthermore, wind tunnel tests, in combination with fluid dynamics modelling, will be conducted to optimise the application methods and the effect of different substrates, icing fluids, contaminants etc., thus correlating the aerodynamic and de-icing behaviour to the morphology of the material. The performance of the developed coatings was compared with that of existing coatings provided by a partner of the consortium. The material with the most promising performance, as deduced from characterization data, was produced in large-scale and provided to the partner “British Airways” for applying it as topcoat in a selected airplane and testing it in actual flight conditions.

2. Work performed
Several preparation and functionalization schemes for the development and the modification of the developed metal oxides or nanostructured carbon nanoparticles have been applied by Glonatech and NCSRD in order to increase their dispersion in the resins/paints of interest. Mainly, two types of coatings were investigated within the project as suggested by partners British Airways and Bionanovate. Several formulations of functionalized nanoparticles / paints have been prepared at the facilities of NCSRD and Bionanovate and applied on primed/painted surfaces either by spray deposition or hand application to determine the nanoparticles weight percentages that can ensure uniform and stable dispersions.
Subsequently, the contact angle values were determined for selected coating formulations in order to account for their hydrophobic nature. In several cases samples, the contact angle was improved by 18-47% - depending on the incorporated nanomaterials - over the paints that did not contain nanoparticles. The wettability of the surfaces, using common de-icing fluid, was also investigated and was found not to be significantly affected. RMS surface roughness was determined employing Atomic Force Microscopy (AFM) and revealed that there is a clear reduction of the RMS roughness due to improved surface coating. This result will be further investigated, along with the testing of additional formulations that contain nanoparticles with new functionalities and the optimization of the application techniques of the best performing coatings to date.
Furthermore, the most promising formulations were evaluated as to their effect in wind tunnel tests and by simulations with computational fluid dynamics (CFD), both at Kingston University. The key results obtained indicate that the boundary layer thickness is certainly thinner and the stagnation points are moved towards the upper surface. The most efficient coating, in terms of hydrophobicity, roughness and anti-icing behaviour, was applied as topcoat on a British Airways airplane, and real-time flight data were obtained that corroborated the materials performance improvement

3. Results
SANAD project has contributed to the enhancement of knowledge and multi-disciplinary skills of researchers by sharing multi-faceted knowledge and expertise towards development of novel nano-coatings that can operate in practice in an efficient, safe and economically viable manner in aerospace and other transportation applications. Apart from the individual benefit for the participant researchers and technical personnel, the consortium has promoted product quality and reliability by ensuring process safety and “environmental friendliness” via optimization of the cost for energy and raw materials. The latter is the result of high-throughput production and modification of nanoparticles, which will lead to the reduction in the preparation cost and energy expenditure as well as to minimization of the cost of post-functionalisation.
In addition, more environmentally friendly modification treatments have been carried out in order to avoid the use of large quantities of solvents and surfactants, thus reducing the treatment cost. Finally, the developed top coatings can lead to the reduction in the build-up of debris on the plane’s main structure, the leading edge of the wings and other areas, thus decreasing friction and drag on the surface of the aircraft. This translates to lower carbon emissions, as well as to the reduction in the fuel consumption of the aircraft and the overall flight cost.

4. Potential impact and use
SANAD has contributed to:
a. Enhancement of the international cooperation in the area of nanocomposites coatings, through targeted actions related to their design, preparation, characterisation and potential use that involve joint efforts by the participating SMEs and research partners.
b. Consolidation of the ability of the SME partners to be self-standing in terms of R&D capacities and enhancement of the business skills of the academic/research partners.
c. Boost of the research potential of the participating SMEs (principally) and the R&D partners, through targeted activities in specific research areas related to nanotechnology-based materials.
d. Improvement of the research management capacity of the SME partners
e. Organisation of outreach actions that should act as a bridge in strengthening bonds of the partners with the industrial and academic communities.
f. Upgrade of the scientific value of SANAD members through the recruitment of leading experts, the training of personnel and two-way secondments.
g. Promotion of the dissemination of knowledge and innovative R&D activities produced by the members of SANAD consortium.

5. Participants
a. Glonatech S.A. Greece
b. National Center for Scientific Research Demokritos, Greece
c. Bionanovate Ltd., UK
4. Kingston University, UK
5. British Airways, UK