The small size, lightweight nature, and beneficial properties of many nanomaterials mean that they have been of interest to many high-tech industries, especially those that require high-performing mechanical properties, such as the automotive and aerospace industries. With increased funding for aerospace applications, a number of nanomaterial producers are working with the aerospace industry to improve the parts and systems of aircrafts using nanomaterials.
Given the interest and investment, alongside the need for constant innovation in the aerospace sector, it won’t be long before we start to see nanomaterials regularly used in aircraft. Here, we look at some of the key areas currently emerging and in which areas nanomaterials have the most potential.
Lightweighting and Improved Mechanical Properties
In the aerospace industry—and any transport industry for that matter—lightweighting is one of the most vital properties a material needs to possess behind safety/stability. The aerospace industry is constantly trying to reduce the weight of their aircraft while keeping the same level of, or better, mechanical integrity in their frames and parts. The lighter a plane is, the less fuel it will use. Using less fuel not only saves on carbon emissions and improves fuel efficiency; it also reduces the cost of each flight.
Over the years, planes have continually become lighter, and the small size and lightweight nature of nanomaterials present an opportunity to create even lighter aircraft. Composites are widely used to build the aircraft frame. Integrating nanomaterials into these composites enhances the airframe and internal components’ stiffness, strength, and robustness properties while making the aircraft lighter. Alongside enhanced mechanical properties, integrating nanomaterials can also introduce improved heat transfer and heat endurance properties to the airframe.
One of the key benefits of using nanomaterials is that you don’t need to use much of a nanomaterial in a composite to see benefits. Benefits are typically realized within a few wt%, or even less than 1 wt% in some cases. Introducing such a small amount can also reduce the amount of material required to perform the same function. So, as well as using a lighter additive, the reduction in material requirements can be used synergistically to reduce the aircraft weight.
The potential for nanomaterials to move beyond conventional composites exists as well. In recent years, there has been much interest in using additive manufacturing to create hot zone engine parts (made from metal alloys) and 3D printed composite materials. The potential for integrating nanomaterials into 3D printed thermoplastics is promising, as this could be a cheaper and quicker way of replacing both critical and non-critical parts, especially small and intricate parts, in aircraft while ensuring that the mechanical and wear properties of the part remain sound.
Various Levels of Enhanced Protection
Nanomaterials have the potential to protect aircraft from the harsh elements they fly in and from the many different factors that can affect the aircraft during flight. Many nanomaterials have excellent stability, alongside excellent conductivity/dissipation, or insulation properties (depending on the material in question and the application). This protection can be realized by either integrating the nanomaterials into the aircraft mainframe composite structure or as a protective barrier coating on the surface of the aircraft, allowing either the direct blocking or dissipation of an external hazard.
An example of an external hazard that can affect aircraft is lightning. Aircraft are always at risk of lightning strikes, especially on the wings, and if the energy is not dissipated effectively, it can cause severe structural damage to the aircraft. However, by integrating/coating highly conductive nanomaterials, such as graphene, into the wings of planes, you can get a lightweight solution that will electrically dissipate the energy from the lightning strike. In many planes, metallic structures, which are heavy, are used to dissipate the lightning, but there is a drive for more composites to be used. So, nanomaterials offer the potential for the creation of lightweight conductive composites that could efficiently replace the metallic status quo.
The integration of nanomaterials into critical components of an aircraft also prevents ice from building up on these components, and the external surface in general. Alongside a reduced weight, the addition of nanomaterials in different components alleviates the thermomechanical stress during heating cycles and provides higher efficiency and lower power consumption. The inherent stability of nanomaterials and the subsequent stable composite structure could help reduce ice buildup, protect critical components, and prevent aerodynamic stall in aircraft.
Many nanomaterials—especially inorganic materials, plus some organic materials like graphene—have a high resistance to temperature, so they can withstand very high temperatures without breaking down. When these materials are integrated into other materials, be it in the different plastics used throughout the aircraft or in the textiles used for the upholstery of the aircraft, they introduce fire retardant properties to the material. As well as providing improved resistance to fire, the introduction of nanomaterials into other materials can also reduce the level of toxic fumes released if they do catch fire.
The addition of nanomaterials into the airframe and structural components within an aircraft can also dampen the vibrations that enter the interior of the aircraft. This could help to diminish noise in the cabin from the outside.
In addition to the other protection enhancements mentioned above, the inherent strength, mechanical properties, and stability of many nanomaterials mean that other protection properties can also be introduced to the aircraft alongside the main benefits. These include a resistance to electromagnetic interference (EMI) and ultraviolet (UV) light rays as well as enhanced corrosion resistance.
Sensors and Monitoring Systems
Sensors are an integral part of aircraft. The sensors in aircraft measure everything from fuel levels to internal temperatures and external conditions as well as various aspects of the engines to ensure that they are performing correctly. Given the altitudes and conditions that airplanes fly in as well as the different internal factors of commercial planes, sensors are an integral technology in the aerospace sector for monitoring and ensuring that all critical systems are working optimally and safely.
The use of nanomaterials in aerospace sensors could prove beneficial. Integrating nanomaterials in sensors usually enables the development of sensors with high sensitivity. The resulting sensitivity can be greater than or equal to bulkier sensors if the right material is used as the active sensing surface. The lightweight nature of nanomaterials means that you can create very small, highly efficient sensors. For aerospace applications, this presents two key benefits.
- Because nanomaterials enable designers to create smaller sensors, the aerospace industry can fit more sensors into different aircraft systems to monitor more parameters, increasing the overall safety and optimization of aircraft systems.
- Because nanosensors are much smaller than other sensors, they are also much lighter. So, for aircraft where lightweightness is key, nanomaterials offer a way to reduce the weight of the sensors used in the craft, which has a positive effect on the fuel efficiency and fuel consumption of the aircraft.
In addition to the more conventional monitoring-based sensors, nanomaterials could deliver potential benefits in the hyperspectral cameras at the front of the aircraft. Leveraging the broad electromagnetic spectrum bandwidth that many nanomaterials possess, nanomaterial-enhanced hyperspectral cameras could detect visible light, near-infrared (NIR), short-wavelength infrared (SWIR), and long-wavelength infrared (LWIR) wavelengths as well as provide effective detection capabilities even in poor weather and visibility conditions.
Conclusion
The small size, lightweight nature, and stability of nanomaterials, alongside other specific properties such as high electrical conductivities, means that there are many areas where the integration of nanomaterials into existing composites, coatings, and electronic devices will bring about benefits to the aerospace industry. These include, but are not limited to, improved lightweighting of the aircraft, protection against the elements, and in various sensing and monitoring devices within an aircraft.
If the funding and innovation drive continues at the nanomaterial-aerospace interface, then it won’t be long before nanomaterials are used on a wide scale, and the use of nanomaterials in aircraft is something that we could possibly expect to see more and more in the future.
Author
Liam is Senior Science Communications Officer at the Nanotechnology Industries Association (NIA) in Europe and has spent the past few years writing for companies, associations and media websites around the globe. Before becoming a writer, Liam completed master’s degrees in chemistry with nanotechnology and chemical engineering. Aside from writing, Liam is also an advisory board member for the National Graphene Association (NGA) in the U.S., the global organization Nanotechnology World Network (NWN), and a Board of Trustees member for GlamSci–A UK-based science Charity. Liam is also a member of the British Society for Nanomedicine (BSNM) and the International Association of Advanced Materials (IAAM), as well as a peer-reviewer for multiple academic journals.
