The aerospace industry is prepared to take off like never before. As demand for faster transportation increases, the Federal Aviation Administration is considering regulatory changes to accommodate companies that want to bring back supersonic commercial jets, Simple Flying reports. Meanwhile, the Department of Defense is pursuing a $2 billion U.S. Space Force, says DefenseNews. Trends such as this will help propel the aerospace and defense market to $8.7 trillion in revenue over the next 20 years, an increase of $600 billion from projections a year ago, Boeing forecasted at this year’s Paris Air Show. The need to upgrade commercial jets to more fuel-efficient models and demand for modernized military aircraft will both help drive this growth.
The growth of the aerospace industry depends on advances in underlying technology that makes improvements in air travel possible. One unsung but essential component of aerospace design is sealing technology such as o-rings and grommets. Here’s a look at three innovations in sealing technology that are helping make aerospace advances a reality.
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Sealing Aircraft Against High Temperatures
One of the perennial issues aircraft manufacturers must address is dealing with the effects of high temperaturea during flight. Aircraft are made from components that have different coefficients of thermal expansion, which means that joints holding different materials together are prone to come apart as the plane cycles through transitions from low to high temperatures and back again.
To address this, manufacturers need sealing materials that can retain their properties under high temperatures without becoming altered when returning to low temperatures. Experience has shown that silicone rubber, which can be modified to handle a temperature range from -85 degrees to over 400 degrees Fahrenheit, offers an ideal solution to this problem. In addition to handling heat changes well, silicone also resists the effects of pressure, electricity and ultraviolet radiation. For these reasons, silicone aerospace applications are favored on dozens of aircraft parts, including everything from door gasket seals to cockpit instruments to fuel tanks.
Staying Sealed in Subzero Temperatures
At the other temperature extreme, engineers seeking to find more efficient alternatives to conventional jet fuels are exploring the use of liquid hydrogen as an alternative energy source for aircraft. This presents a challenge because liquid hydrogen used for fuel must be stored at -432 degrees Fahrenheit, colder than rubbers such as silicone can handle.
One specialized rubber being adapted for this sealing application is polytetrafluoroethylene (PTFE, commonly known as Teflon), which can be modified to handle cryogenic temperatures and is commonly used for o-ring and grommet seals for liquid hydrogen and other extremely cold substances such as liquid helium. Another alternative researchers are exploring is indium, a soft, malleable metal that acts as a superconductor at temperatures above -453 degrees Fahrenheit.
Developing Seals to Resist Chemical Corrosion
Temperature extremes aren’t the only sealing challenge aerospace manufacturers must overcome. Harsh chemical environments can also weaken seals or cause them to fail. Fuels, corrosion and solvents are some of the chemical factors that aircraft sealing materials must be able to withstand in order to hold up under flight conditions.
One way researchers are addressing this issue is by modifying silicone rubber to make it more resistant to chemical changes. Another approach is using alternative rubbers such as perfluoroelastomer (FFKM or Kalrez), which resists over 1,800 different types of chemicals and can also handle high temperatures, making it popular for aerospace applications such as sealing gearboxes.
Aircraft and spacecraft designers depend on sealing materials such as silicone, PTFE and FFKM that can handle any temperature extremes as well as harsh chemical environments. Dependable sealing materials help ensure high performance under all conditions, allowing the aerospace industry to continually reach new heights.
