Manufacturers in aerospace and aviation have used silicones since their inception, however not everyone is familiar with all of their capabilities. Silicones seal joints, coat and encapsulate electronics and insulate and shield sensitive equipment from extreme temperatures and weather exposure. The versatility of silicone and its high temperature resistance have made it a reliable choice for decades and today it is still one of the most effective materials used in aerospace and manufacturing.

Silicone supports engines that experience high temperatures during liftoff, as well as on the exterior of a space capsule that experiences low and high temperatures and needs shock absorption when re-entering Earths atmosphere. Silicones effectiveness and versatility make them suitable for atleast 20 different areas of a launch vehicle.

RTV Silicone Rubber:

RTV Silicone rubber is short form of room temperature vulcanization silicone rubber. Once part A and part B mixed together at normal room temperature, it will create High flexible to medium flexible rubbers. RTV silicone is available in a variety of viscosities-ranging from low viscosity options that can be incorporated with additives to boost the thermal protection properties, to high viscosity formulations that can be applied to overhead surfaces.

Aviation applications

  • Silicones are very effective for aircraft original equipment manufacturing(OEM) and for maintenance, repair and overhaul(MRO).
  • Aircraft components are frequently replaced due to wear experienced through time. Silicone offers convenience and efficiency benefits in MRO because it comes in individual use tubes for easy delivery and in dual cartridges that deliver the materials precisely and simultaneously to save time and avoid product waste.
  • Many epoxy and polyurethane adhesives can become rigid when cured and may not be able to absorb Coefficient of Thermal Expansion(CTE) mismatches between different substrates. Silicones have a low modulus that maintains flexibility even in extreme high and low temperatures, allowing silicone adhesives to more effectively cope with CTE mismatch effects.

Aircraft applications

  • Black box encapsulant
  • Avionic display unit adhesion
  • Protective coating for critical circuits, terminals
  • Radome sealant
  • Sealant, encapsulant: computers, LED modules, sensors
  • Engine component, thrust reverser thermal protection
  • Fuel tank coating, sealant
  • Epoxies and polyurethanes generally offer poor electrical properties at low or high temperatures and in damp conditions. They can also be harder to work with due to toxicity and an affinity for water absorption, and they are difficult to remove or repair when equipment needs to be serviced.
  • The strongest attribute of an RTV silicone is its ability to maintain critical properties throughout a wide temperature range. That temperature range makes RTV silicones suitable to bond lenses onto telescopes and secure optics onto satellites and other structures. Since this equipment remains in orbit for a long time, it is subjected to large temperatures fluctuations due to repeated, intermittent exposure to the sun, and silicones can withstand those extreme conditions.
  • A silicone coating is applied to electronic components to protect against extreme environmental conditions. RTV silicone are rubber and gel silicones that cure without heat and are used for bonding, sealing, encapsulation, coating and potting applications.

Other benefits of room temperature vulcanized(RTV) silicones

  • Heat resistance, flexibility-In thermal protection systems, RTV silicones can maintain their properties in extreme heat, such as securing thermal sheilds on the exterior of aircraft and space vehicles. They can maintain adhesion during the extreme heat of re-entry and remain elastomeric in low-temperature environments. They also protect launch pads and structures during launches and landings.
  • Spark, fire protection-RTV silicones resist long term smoke and fire penetration. They can be self-extinguishing, and the fumes from ignition are non-hazardous to humans. Silicones also insulates fuel lines to help keep fuel flowing in the event of an engine fire.

Electronics applications

  • Advanced aviation electronics have a very high power density that generates more heat than those typically used in the past. When circuit boards that support the operation of planes and radar systems generate heat, onboard electronics are also constantly exposed to fluctuating temperature throughout their lifespan. To last longer, electronics coatings and adhesives must outlast the effects of repeated temperature changes.
  • Room temperature vulcanizing(RTV) silicones are a prominent ingredient in aerospace manufacturing due primarily to their ability to withstand extreme temperatures while maintaining their physical properties. When protecting these delicate electronics and circuit board assemblies or sealing power modules and sensors, manufacturers should use compounds that provide stable dielectric, thermal and mechanical properties such as silicones. Thermally conductive silicones can also passively remove heat. There are many methods to apply liquid silicone to sensitive components, such as with pneumatic applicator guns, syringes and metered dispensive valves. The silicone is then cured into an elastomeric rubber that excels in thermal interface applications.
  • Electrostatic dissipative and electromagnetic shielding silicones can electrically ground composite structures while tolerating a low electrical charge.
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