This text is part of the special section Relève en recherche
After helping to protect aircraft from lightning strikes, Polytechnique Montréal postdoctoral candidate David Brassard sets out to develop nanoporous carbon sponges to capture water from the air and provide a potential solution for fueling. drinking water from isolated communities.
With his team, David Brassard prepared plates of carbon fibers covered with silver. Each plate was placed in a lightning emulator, a device that produces electric shocks of over 40,000 amps – more than 2,000 times more intense than current from an electrical outlet. The team measured the damage on the plate using a thermal imager, then tested whether the material retained its mechanical properties after discharging. The engineers repeated the operation with other plates of different thickness. Their goal: to find the ideal formula to cover aircraft and protect them against lightning.
“An airplane can be struck by lightning once a year on average,” reveals David Brassard, specifying that lightning then passes through the frame of the device without causing damage. “This generally happens every 3000 hours of flight, often in the take-off or landing phase, at an altitude of 3000 meters,” he continues, explaining that these events generally go unnoticed by passengers. “Formerly, planes were made of aluminum, and the structure of the aircraft was conductive [d’électricité], which meant that there was very little damage during the lightning strike, ”he explains.
“With the introduction of aircraft made of composite materials – assemblies of immiscible components whose properties complement each other – we have a structure that is no longer conductive as before. We must therefore add a layer that will protect the composite, ”continues the researcher, who specifies that these new materials reduce weight and consumption. [de carburant] machines. Currently, copper grids are used to protect aircraft made of composite materials; on the other hand, these screens are very heavy.
“The project in which I am currently working aims to develop a lighter protection system”, explains the researcher, who concludes his participation in this project carried out in collaboration with industry. Silver coated carbon fibers have already proven their effectiveness in this area, but on a tiny scale. The team is now trying to adapt the composite to aircraft scale.
Carbon sponges for isolated communities
In another Polytechnique Montréal laboratory, engineers play with the properties of a completely different element: water. They develop a composite that will play the role of a sponge capturing water in the air. More precisely, it is a carbon-based resin which has undergone a pyrolysis treatment, that is to say which has been heated without oxygen to create nanopores. Thanks to the phenomenon of capillarity, the water in the air adheres to the surfaces of the nanopores, until the water molecules form droplets. The process is done passively; only collecting water through heating requires a little energy.
“There are other universities that are doing research in this direction with other materials, such as metal organic framework (MOF). They have very good laboratory performance, but when you come to scale them, it doesn’t work because it is very complex and expensive to manufacture these materials, ”says David Brassard, enthusiastic about starting his work. second postdoctoral fellowship with this team which seeks to develop a process at a lower cost.
“There are a lot of people who fight day by day to have access to drinking water, and I would like to help these people find solutions to improve their living conditions. We often talk about indigenous reserves that do not have access to drinking water and that have received boil water advisories for thirty years, ”observes Mr. Brassard, who believes that these nanoporous sponges could be part of the solution to the problem. drinking water supply in these communities.
“That’s the advantage of working in research, we can choose projects that correspond to our moral and environmental values,” emphasizes the materials specialist. What motivates me the most is to solve interesting problems, which will have a net positive effect and which will help. “