An airplane trip from New York to Paris currently takes about seven hours, but within the next decade, that may be cut down to an hour-and-a-half, says Atlanta-based startup Hermeus. This May, Hermeus announced its plans to build a commercial aircraft that will fly at speeds of Mach 5, equivalent to over 3,800 miles per hour. That’s over five times as fast as current commercial aircraft, which are powered by turbocraft engines that function most efficiently at speeds of 400 to 620 miles an hour. To achieve Mach 5 speeds, Hermeus will rely on turbine-based, combined-cycle engines, along with a titanium-based frame.

Achievements such as this are shaking up the global aircraft industry, putting the aerospace and defence materials market on track to grow to a value of $27.44 billion by 2025, projects Grand View Research. The growth of the aerospace industry is powered by engineering innovations that happen under the hood, including ones involving parts as small but essential as o-ring gaskets, which will account for $249.5 million a year by 2024, predicts Stratview Research. Here’s a peek at three of the latest developments in aerospace sealing that are helping make advances in travel technology possible.

Silicone Applications

Silicone has been an important material in aircraft design since the early days of the aviation industry, and its importance continues to grow as innovative applications of this versatile material emerge. Silicone materials combine flexibility with a low compression set, meaning they return to their original shape easily after being subjected to pressure. Silicone also has one of the widest working temperature ranges among elastomers, with standard compounds retaining their properties between -80 degrees and 400 degrees Fahrenheit, a range that can be extended through customization. Silicone further has high dielectric strength, meaning that it retains its insulating properties when exposed to electricity. Due to these properties, silicone can absorb stress during thermal cycling, and it also resists breakdown when subjected to high temperatures or ultraviolet light.

This combination of properties makes silicone extremely useful for aerospace applications. For instance, silicones can be used to hold together parts of an airplane that react differently to heat and would otherwise come apart. They can be used to insulate materials from the effects of heat and vibration. Silicone o-rings are used for seals in aircraft. Silicone can be used in no less than 20 different parts of an aircraft. Recent research has focused on developing silicone-based elastomers that are even more fuel and solvent resistant than standard silicone.

PTFE (Teflon) Applications

Another increasingly important material in aerospace design is polytetrafluoroethylene (PTFE), most commonly known under the brand name Teflon. Manufactured from fluorocarbon, PTFE has exceptional nonstick qualities as a result of its low friction coefficient, which is among the lowest for solid materials. PTFE also resists temperature changes, electricity and corrosion.

Like silicone, PTFE is used extensively throughout aircraft designs. Its applications include providing low-friction coating for slide bearings, protecting surfaces from friction and insulating cable. One of its most important recent sealant applications is sealing hydraulic systems.

Perfluoroelastomer (FFKM) Applications

Another innovative material that has become important in aerospace applications is perfluoroelastomer compounds such as FFKM, which goes by brand names such as Kalrez. Developed by DuPont, FFKM contains more fluorine and less hydrogen than other fluoroelastomers, which increases both temperature and chemical resistance to combine the toughness of elastomers with the chemical inertness of Teflon. FFKM has increased resistance to temperatures as high as 600 degrees Fahrenheit. It also resists most chemical reactions, allowing it to serve in corrosive environments that would damage other elastomers. It further exhibits less deformation over time when subjected to a continuous load than Teflon.

These properties make FFKM useful for aircraft applications that other materials can’t handle. Because it is more expensive than other materials, its use is usually restricted to cases where it is the only suitable option. In jets, it has recently been used to seal gearboxes and bearing chambers because of its resistance to temperature and turbine lubricating oils.

Innovative developments of silicone, PTFE and FFKM are helping increase the efficiency of sealing applications in aircraft and spacecraft. They play a critical role in supporting essential components of aircraft such as engines, hydraulic systems, gearboxes and airframes. These components in turn allow aircraft to handle the harsh temperatures and chemical conditions that make efficient air travel possible.