Cryogenic Treatment for Aerospace Engineering
- September 3, 2020
- Controlled Thermal Processing
- Aerospace
The term cryogenic often comes up in discussions about aerospace applications. Aside from pop culture associations with cryogenic sleep or “suspended animation”, there are plenty of practical applications for cryogenic technology within the aerospace industry.
This includes the use of cryogenic fluids to cool jet engines and in-flight components, the storage of rocket fuel at extremely low cryogenic temperatures, and the cryogenic sampling of gases in the stratosphere.
On top of all these uses, cryogenic hardening technology is used by materials engineers to prepare metals for the rigors of flight or space travel.
In this article, we’ll take a look at some of the techniques used in aerospace fabrication, as well as how cryogenic treatment can make your aerospace parts stronger.
What is aerospace fabrication?
Aerospace fabrication refers to the construction of vehicles for flight – both within and beyond Earth’s atmosphere. These vehicles can be anything from airplanes, rockets, and sailplanes, to hot air balloons and blimps.
While manned flight has been around since the early 1900s, it wasn’t until the 1930s that aerospace manufacturing really took off. Early airplanes were made with wooden frames and fabric skins, but these were soon replaced with aluminum alloys.
Specialized craftsmen were required to produce metal wings and fuselages, as well as to forge landing gear parts. New techniques, such as welding and riveting, made the process more streamlined, not unlike the assembly-line production of automobiles.
Later on, jet propulsion technologies carried the industry even further, spearheading the development of onboard computers to control various aspects of the aircraft.
Today, the aerospace industry includes the manufacturing of components for major flight subsystems and support systems, as well as products used in related industries.
Airplane and spacecraft systems are incredibly complex, so specialized equipment is integral to the aerospace industry. The design and fabrication of these parts helps to ensure the safety of everything from commercial planes to spacecraft.
Where does cryogenic hardening come in?
The word hardening is commonly used to denote enhanced. Wear resistance enhancement associated with cryogenic processing does not depend entirely on hardening. Other mechanisms are at play during cryogenic processing which result in longer service life.
Some of these mechanisms involve residual stress relief, creation of fine carbide precipitates, enhanced fatigue life, and enhanced dimensional stability.
Cryogenic processing typically entails a slow cooling to cryogenic temperatures, a dwell period at this low temperature followed by a slow return to room temperature and finally a first stage tempering.
When steel components are manufactured, they sometimes contain residual amounts of austenite (a phase of steel), which is relatively soft, having low tensile strength and poor wear resistance.
What cryogenic hardening does is induce a phase transformation from austenite to martensite, among other changes. This improves qualities such as hardness, electrical conductivity, and susceptibility to corrosion.
Cryogenic hardening can be performed on a variety of metal parts, from common car parts such as brake rotors to more specialized aerospace components.
It requires a carefully-calibrated application of cold and heat, usually done over a period of 24 hours using an industrial-grade cryocooler. The metal will be taken to sub –238 °F temperatures, then heated to 300 °F or more, then allowed to cool.
The importance of cryogenics to aerospace parts fabrication
For critical components in the aerospace industry, it’s important to use only the highest quality materials available. Cryogenic hardening can be used to strengthen metal parts in communications systems, guidance systems, landing gear, and more.
Aerospace equipment undergoes enormous stress from the forces applied during take offs and landings. Cryogenic hardening can help aerospace materials withstand these forces and reduce in-flight malfunctions.
Why not just use stronger materials to begin with? In short, because steel that contains high levels of austenite has increased ductility, making it easy to form into various parts and components.
Once the component has been formed, however, ductility is no longer an asset.
That’s why conventional heat treatment is performed to convert austenite to a more desirable phase. Then cryogenic processing is used to complete the phase change and confer other beneficial changes.
Also, unmanned spacecraft may experience cryogenic conditions during use in the cold of space. For example, lunar rovers experience the phenomenon known as lunar night. At any given location on the moon, daylight (lunar day) lasts about two weeks followed by about two weeks of darkness known as lunar night.
During the lunar night, temperatures drop into the cryogenic range, risking the survival of the rover. Using cryogenic hardening to prep critical components may help the rover survive these bitter cold conditions.
Primary suppliers of aerospace fabrication services
Some of the largest aerospace companies in the U.S. include Boeing, Lockheed Martin, Northrop Grumman, United Technologies, and Raytheon. These companies are so big and influential that some of them have become household names.
But there are also many smaller aerospace equipment manufacturers that support these larger corporations. These smaller manufacturers are often highly specialized experts in a particular area of aerospace fabrication.
Here are just a few of the top companies in aerospace fabrication:
- Arconic produces a variety of lightweight metals and parts that range from fuselage panels to fasteners (Pittsburgh, PA)
- Amphenol is the leading supplier of interconnect products for aircraft engines (Wallingford, CT)
- Senior Aerospace makes engine parts, duct fittings, and nacelle attachment rings (Burbank, CA)
- Griffon Aerospace manufactures composite unmanned aircraft and supplies major aerospace companies with advanced designs (Madison, AL)
- Aerospace Structural Research Corp. offers engineering consulting services for spacecraft and aircraft components (Milford, CT)
Other big players in the aerospace consultation and fabrication space include:
- Airmods LLC (Colorado Springs, CO)
- Woolf Aircraft Products (Romulus, MI)
- Pentad Design (Tustin, CA)
- Warehouse Equipment & Supply Company, Inc. (Birmingham, AL)
- ABB Inc. – Instrumentation & Analytical (Wickliffe, OH)
- Falcon Electric, Inc. (Irwindale, CA)
- Global CNC Industries, Ltd. from (Plymouth, IN)
- Industrus Manufacturing & Consulting Inc. (Riverside, CA)
This range of engineering and manufacturing firms helps the U.S. aerospace industry run smoothly by providing their specialized fabrication expertise.
In addition, cryogenic treatment providers like CTP Cryogenics are integral to making sure these parts last longer and can withstand the stresses of flight.
Multi-layer insulation in aerospace
Multi-layer insulation blankets are a type of product used in aerospace manufacturing to protect vehicles from excessive heat loss or gain due to the harsh conditions of space.
The outside is covered in a thin reflective layer which fends off excessive heat from the sun, while materials inside help to keep the vehicle warm enough for flight.
These multi-layer insulation blankets use the same principles as a thermos to insulate the spacecraft. Just as a vacuum layer between the inner and outer shells of a thermos can prevent heat transfer, the space between layers in a multi-layer insulation blanket can prevent heat transfer from one layer to another.
Multi-layer insulation often has the appearance of gold or silver foil wrapped around a spaceship or satellite. The fiberglass fabric gives it enough flexibility to wrap around a variety of craft designs, and a single blanket can have up to 40 layers.
The fabric’s design allows for trapped gas molecules to escape more easily, improving the insulative properties of the material. Multi-layer insulation blankets are especially important for the insulation of ducts and external attachments.
The materials that these blankets are made out of must be extremely durable as they will be subjected to the rigors of the environment in space for extended periods. This includes intense heat from sunlight shining on the spacecraft and extreme cold when the sun is not directly shining on the spacecraft, such as during lunar night.
The materials must also maintain their physical properties in a vacuum, and must be lightweight, since every ounce matters when trying to launch a craft into orbit.
MLI blankets are used on everything from satellites and spacecraft to aircraft. They’re also used on the International Space Station, which has multi-layer insulation in areas such as the airlock, the lab, nodes, and truss elements.
For improved safety and longevity of your aircraft, consider using cryogenic processing to increase the lifespan and durability of your aerospace parts. And, consider shielding your equipment from the elements by using high-quality multi-layer insulation on ducts, seals, and other mission-critical devices or structures.
Make sure your aerospace parts get the treatment they need
Whether you’re producing common metal parts for commercial aircraft or specialized parts for unmanned spacecraft, aerospace components have to be able to withstand strong forces, extreme heat, and in some cases, the vacuum of space.
Structurally weak materials are unable to withstand these harsh conditions, and using the highest-quality materials only goes so far. Cryogenic processing can increase the lifespan of metal parts in a range of industries and applications.
At CTP Cryogenics, we have over 40 years of experience providing Controlled Thermal Processing for vehicles used on land, sea, or air. We can lead you through the process of selecting the best treatment for all the materials on your craft.
With several convenient locations around the U.S., we can ensure that your parts are processed promptly to avoid any delays in your supply chain.
Contact us today to get a free quote and learn more about cryogenic processing!
