Researchers at the University of Central Florida (UCF), in the United States, made a discovery that can help reduce costs for the aeronautical industry and airline service companies. It is about a extremely light and economical paint that does not require pigments to have a certain color.
Experts were inspired by nature’s wealth of colors to develop the material. As an example, the vibrant tones of peacocks are caused by microscopic irregularities on the surface of their feathers which, when interacting with natural light, create the iridescent green and blue appearance. This phenomenon is known as “structural color”.
During an experiment, whose initial objective was to manufacture a continuous aluminum mirror using beams of electrons, the scientists were faced with the difficulty in making the surface perfectly regular. Although they were invisible to the naked eye, the small “blemishes” were large enough to interrupt the mirror’s glare.
The ruptures, called “nanoislands”, appeared all over the surface of the material. Scientists observed that aluminum electrons became agitated when interacting with natural white light. Furthermore, the particles interacted with different wavelengths of light, depending on the size of the nanoislands.
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Upon reaching the uneven surface, the white light was reflected as a color. “Just by changing the size of the nanoparticles, you can really create all the colors,” said Debashis Chanda, a professor at UCF’s Nanoscience Technology Center and one of the authors of the study published in the journal Science Advances on March 8.
Structural color serves as the primary color generation mechanism in many extremely vivid species, where the geometric arrangement of typically two colorless materials produces all of the colors. On the other hand, with the artificial pigment, new molecules are needed for each color present.
Debashis Chanda
Professor at the Technological Center for Nanoscience at UCF
With this discovery, the team began to elaborate different paint colors using aluminum nanoislands in a double-sided mirror with a thickness in the nanometer scale. Then the leaves were crushed to be reduced to powder, so that it could be easily mixed with the binder used to manufacture ink.
New paint could save jet fuel
Chanda explains that the structural nature of paint allows a thin layer to be enough to color a surface. A single drop of the material would be enough to paint both sides of a door., according to the researcher. The lightness of the substance can have important applications in industry, especially in the manufacture of aircraft.
As noted by the research team, a Boeing 747 needs over 450 kg of paint to be colored. The professor estimates that just 1.3 kg would be enough to paint an aircraft of this category. In the long run, the weight reduction would yield huge fuel savings for planes, helicopters and other vehicles.
“Given that fuel is already their biggest operating expense, airlines are always interested in improving fuel efficiency,” a spokesperson for the International Airline Trade Association told the Techspot.
In contrast, American Airlines saved more than 400,000 gallons of fuel—about $1.2 million in one year—by simply removing 70 pounds of pilot’s manuals on board planes. The efficiency of the aircraft could see a significant leap forward by reducing almost half a ton of its weight with the use of the new paint.
Better durability and heat dissipation
Another advantage of the new paint is its resistance. Airlines need to repaint planes four times a year on average. The wear and tear of the artificial pigment occurs due to continuous exposure to solar radiation. Structural colors do not have this problem, and only need to be reapplied if the company needs to change the colors of the vehicle.
Furthermore, the ink does not change its heat retention according to its coloring. Aircraft are often painted white for their better ability to reflect light, reducing the absorption of infrared radiation. Preliminary tests suggest that the paint can maintain the surface of the aircraft between 20ºC and 30ºC.
Experts cite painting cars, buildings, and a host of other applications that could take advantage of the paint’s better heat dispersion in order to save energy costs on air conditioning and other cooling solutions.
Now, the challenge is to put the technology into mass production. The laboratory is looking for partners to invest in equipment that can produce the new ink on a large scale for commercialization.