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Aircraft painting with a “green” focus: new research

The researchers are designing a new formula, as well as a new
application system, for paint coatings based on sol-gel technology that
can be used in the aeronautical sector. The project’s main goal is to
find a more ecological alternative to be used in the airplane painting
process. Specifically, the researchers hope to develop a new,
competitive sol-gel product along with a versatile system for applying
it, for both maintenance operations and the manufacture of the
aircraft’s original parts.

The GreenGELAIR project attempts to solve a problem posed by the
paints that are currently used in various industries. These paints
contain hexavalent chromium and, according to environmental regulations
(REACH), must be substituted for others in the majority of sectors,
particularly the aeronautics sector. To this end, Sol-gel technology is
seen as one of the clean alternatives to coatings made up of chromium,
according to the researchers. “The proposed sol-gel system will be
versatile and competitive,” they state, “minimizing maintenance
operations and costs, and eliminating the environmental problems raised
by the current systems.” They point out that the project’s results can
be applied in sectors other than aeronautics that use similar surface
treatments.

With sol-gel technology, which is based on molecules composed of
oxygen, silicon, hydrogen and carbon, certain chemical reactions are
produced. These reactions lead to the formation of a polymeric coating
network that can contain ecologically acceptable corrosion inhibitors.
“When applied correctly, they form continuous, homogenous coatings that
create an adequate barrier to corrosion even in extreme conditions,”
they note. This technology offers additional advantages, such as the
fact that non-toxic solvents can be used and that work can be carried
out at normal room temperature.

In search of a clean sky

The project, which was begun in October of 2013, is expected to last
two years. During that period, the scientists will complete the
formulation and kinetic study of the project, as well as designing and
constructing an application device and testing its efficacy on complex
parts. In order to validate the product, different tests of the sol-gel
system’s properties of adherence and protection against corrosion will
be carried out in a variety of settings: large surfaces, small
retouches, complete pieces and patches of fuselage. The researchers in
UC3M’s Grupo de Tecnología de Polvos (Powder Technology Group) who are
taking part in this initiative are going to be in charge of the “design
and preparation of these new coatings in the laboratory in order to then
analyze their resistance to corrosion,” explains Professor Antonia
Jiménez Morales, of the Department of Materials Science and Engineering
at UC3M.

The GreenGELAIR project was approved in the first call for proposals
of CleanSky 2013, part of the 7th European Framework Program. This Joint
Technological Initiative is a research project that is funded by the
European Commission and the continent’s aeronautical industry, with the
goal of creating a sustainable air space and reducing aviation’s
environmental impact. The consortium for this project stands out due to
its broad regional distribution within Spain: UC3M is participating as a
technological partner with expertise in the development of sol-gel
products that increase the adherence of paint to metallic substrates;
the firm GALVATEC, which is located in Seville, is a partner with
expertise in aerospace sector operations, both maintenance operations
and the manufacture of original parts; and the Instituto Tecnológico
Metalmecánico (AIMME – Metalmechanic Technological Institute) of the
Autonomous Community of Valencia, is acting as the coordinator of the
consortium, promoted by the French company Dassault Aviation.