The aerospace industry uses many materials and parts to construct aircraft, some of which are composite and metallic. However, for the most part, composites and metals usually make up most of an airplane’s body with only a few necessary pieces made from other materials. These special pieces are called “specialty parts” or “strategic structural parts.” One important specialty part is Vespel. Here’s what it is and the ways it is used in the aerospace industry.
What Is Vespel?
Vespel ® is a trademark for a high-performance polyamide (a type of plastic) developed by DuPont™. The history of Vespel dates back to the 1960s when DuPont researchers were looking for a space-age material that could withstand high temperatures and extreme conditions.
Vespel has many impressive properties: high strength, low weight, good dimensional stability, excellent high- and low-temperature properties, good resistance to chemicals and solvents, etc.
The process for making Vespel is called chemical vapour deposition (CVD) and is done in two steps. First, the polymer is injected into a plasma chamber, heated by microwaves, and becomes a gas. Then, it is deposited onto a surface as a thin coating of crystals.
The chemical used in CVD uses benzocyclobutene or BCB for short. The final product Vespel has several layers of this material with both crystalline and amorphous (non-crystalline) regions. Here are the ways in which it is used in the aerospace industry.
As A Substrate Material
Vespel can be used as a substrate material for other metals or composites. This is done because Vespel has many benefits, such as its stability at high temperatures, which would allow other materials to bond tightly to it. So a vespel sp211 is used in the horizontal stabilizer of Airbus 350. Similarly, products made from Vespel can also be used as substrates for other materials, because Vespel is non-conductive, it can be used as a substrate to mount electronic parts.
Vespel is used as a coating on fastener buttons in the aerospace industry because it has excellent heat resistance properties. Button screws are usually made from titanium or steel, but due to high-heat exposure, they can become loose and detach which is very dangerous for aircraft flying at high altitudes. So Vespel with a diamond coating is used as a solution. Diamond has an extremely high melting point so it can strengthen fastener buttons and keep the screws tight.
Vespel has a melting point of over 400°C, whereas titanium’s is 660°C and steel’s is 1500°C…so Vespel is perfect for this application.
Circuit Board To Planer Adaptor
Another part made from Vespel is the adaptor that attaches the circuit boards to the planer during satellite manufacturing. The adaptors are used because they can withstand high temperatures, under 125°C for up to 500 hours. This makes it perfect for use in satellites where parts must be able to survive extreme conditions, such as fluctuating temperatures and radiation exposure.
Hot Gas Turbine Casing
Vespel is an excellent material for high-performance applications, especially in the aerospace industry because of its ability to maintain strength at elevated temperatures. For example, the hot gas turbine casing that sits between the engine’s exterior shell and the chamber is a typical application.
The high-performance racing engine of a jet is behind this product, which would reach up to 2000°F. So Vespel with its high heat resistance is used as a coating on its surface because it can withstand such high heat without deteriorating too much. It also has good wear properties, so it is used to protect the engine from sand and other debris.
Vespel SP-21 is used as an expansion joint material that fills up the gaps between two pieces of different metals at their interface. This allows for movement between two elements because if there was no gap, then they could not move or expand at all. This design feature helps to prevent wear and tear on these components during high-stress conditions, such as during take-off and landing.
Joints In A Rocket Engine
Another important application of Vespel is in joints. The aerospace industry uses a lot of joining technology to assemble aircraft and machinery, such as the joints used between rocket engine stages because they experience high heat and vibration during launch. Vespel’s elasticity and heat resistivity properties allow it to withstand this stress without causing any damage.
Vespel is also used as a spherical bearing, which allows parts of machines to rotate or pivot easily. For example, in the F22 Raptor fighter jet, vespel bearings are used to pivot the nozzles of its engines for steering purposes. Similarly, they can be found in other aircraft types, such as the Eurofighter Typhoon.
Heat Shield On The Space Shuttle
Using Vespel in the heat shield of the space shuttle was another big achievement for this material. A major factor in landing a shuttle is making sure it does not burn up during re-entry into the earth’s atmosphere because if it does, then the vehicle will explode on impact with the surface. So NASA used Vespel to protect the shuttle from burning up by covering its surface with a thin layer. The material is able to withstand extremely high temperatures, almost 2000°F without melting, so it was an ideal solution for this application.
Vespel has been used as a protective coating on missile components that must be durable and heat-resistant. The material is able to withstand the stress caused by high winds and other atmospheric conditions as well as impacts from debris and sand that these components are exposed to during launch, so Vespel provides an efficient solution for this kind of application.
Beams In A Nuclear Reactor
Vespel is one of the few materials that can be used inside nuclear reactors because it does not emit any harmful substances and other components cannot easily corrode it. For the beams in a nuclear reactor, Vespel is used as a coating to protect them so they can last for as long as possible because these beams are inside the reactor core where there is a lot of radiation. This application illustrates how Vespel can also be found in heavy equipment because it has good anti-corrosion properties too, which makes it useful for this kind of environment.
As you can see, since it is non-conductive, lightweight, and has high heat resistance, Vespel can be used to make many different types of components in the aerospace industry. Some common examples are missile parts, rocket engine components, and expansion joints. It has proven to be a very beneficial material for this industry because it is strong enough to withstand the stress caused by these high-speed and high-temperature conditions.