Silicone in the aerospace industry

, to better understand the range of potential applications that this versatile material offers. Construction in the aerospace industry is a complex area. After all, keeping a 540ton metal container filled to the brim with equipment, passengers and luggage, is by no means a simple endeavour.

Much is made of the light metals utilised in said constructions, as well as the aerodynamic construction of fuselages and wings, all of which have been tested and refined countless times.

While it's fair to say that there are no ‘minor' components in the construction of such complex and high specification machines, some components and materials do tend to escape the glare of the limelight more than others; the many applications of silicone being one of the best examples of this.

Maintaining pressure, forming seals

When flying at extreme altitudes, it's of tantamount importance to maintain cabin pressure at all times; depressurisation not only makes it difficult/impossible for passengers to breathe, but can result in the downing of the plane if the low atmospheric concentration of oxygen, at the usual operational heights of modern aircraft, is allowed to incapacitate or kill the pilots and crew. Clearly, something needs to keep the pressurised air in, and prevent its replacement with the much ‘thinner' air outside.

This is where silicone comes into play; used in the construction of gaskets for cabin doors and windows, its resistance to extreme temperatures, and the ease with which it can be moulded to an extremely tightly fitting shape, make it the ideal material for such functionality. The silicone gaskets ensure that windows and doors remain absolutely airtight by forming a tight seal around the respective portal, while also allowing plane doors to continue being able to open and close when not at altitude.

As well as maintaining the air pressure of the plane's cabin, silicone is also utilised in the construction of gaskets for use in a plane's engine systems, ensuring that the various chemicals and fluids necessary to keep them operational are transported and stored at the correct pressure. Once again, it's the heat resistance of silicone that makes it so adept at this job; while other elastomers commonly used for gasket construction would be quickly corroded by the extreme temperatures that aircraft engine components are frequently exposed to, silicone is able to maintain its cohesion, and therefore maintain a seal.

Electronics and cockpit instruments

Every component of an aircraft plays a role in keeping it airborne, and the passengers and crew safe, so it's important that each component is kept protected from the uncompromising and harsh conditions found at the high altitudes in which planes normally operate. If one component were to fail, a domino effect could be put into sequence that could potentially bring down the plane. Different components require different levels of protection, from a variety of different environmental aggressors.

Printed circuits require protection from the gamut of potential dangers that they face at ground level; extreme altitudes simply increase the odds of these hazardous situations occurring, and dramatically increase the risk of catastrophic problems being caused, if said hazardous situations are not prevented from interfering with the printed circuits. Silicone sealing can protect fragile circuits from the incursion of hazardous conditions such as excessive moisture and extreme temperature exposure.

Of course, few electrical components thrive on being exposed to moist conditions, or extremes of heat or cold, so silicone is often utilised to provide additional protection to these other electrical components, as well as printed circuit boards. Some of the other problems routinely faced by electrical systems in aircraft are the build-up of ice and the ingress of dust.

Silicone acts as a sheath, and protects wires and electrical components from being shorted, should either dust or ice manage to gain access to the interior workings of a plane. Silicone's highly resistant sealing properties make it ideal for this purpose; silicone is famed for its resistance to biological growth or ingress, environmental conditions as well as its superb electrical insulation and non-porousness.

It's for the reasons above that silicone is also used in the construction of some of the cockpit instruments found in planes. Pressure gauges and other such instrumentation are able to function in a reliable fashion due to silicones resistant and unyielding nature, while other instrumentation is protected from other potential adverse environmental conditions in the same manner.

But the above is not the limit of silicones positive attributes when it comes to the protection of electronics and instrumentation; silicone is also very good at protecting the items on which it is coated from high pressure, and the effects of compression, effectively cushioning the object stored within. Depending on the item, and the area of the plane in which it is contained, this quality may be more or less beneficial.

Interior motives

A lot of noise and vibration is generated due to the very nature of air travel; the high speeds involved, along with the shock of landing, and potential high altitude manoeuvres, all need to be compensated for, in order to ensure continued safe performance, as well as the ongoing comfort of passengers. This is where silicone comes in; silicone's anti-vibration and noise-reduction properties make it the perfect material to reinforce and support passengers and crew during flight, forming a protective layer against the stresses and rigours of travel at such speed.

Silicone is also used to provide support against vibration and excessive noise for a wide variety of facilities and equipment within a plane. Silicone's other elastomeric properties come in handy in particular here, as its flexibility makes it easy to fit into the smallest of gaps, ensuring that all equipment can be protected from excessive vibration and shaking, should the need arise. Silicone's extreme heat resistance, as well as its resistance to UV rays and ozone exposure make it that much more of a viable choice than other elastomers; after all, in a field with as small a margin for error as aeronautics, it's not worth taking unnecessary chances. The additional resistance that silicone has over other similar elastomers just makes it that much more of a safe bet.

Plenty of equipment and facilities utilise silicone for protection against shock and vibration damage, including the seals on infotainment systems and LED lighting; while other facilities, such as overhead lockers, vent ducts and hatches utilise silicone for their seals due its environmental and kinetic resistance, as well as its ability to form a tight closure.

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