Nickel-Based Alloys in the Aerospace Industry
Element number 28 on the periodic table is nickel. This hard and ductile metal, when combined with other metals, such as steel, can form useful alloys. These alloys are magnetic, wear-resistant, and can withstand extremely high temperatures. These properties give nickel-based alloys many effective applications in the aerospace industry.
Aircraft and spacecraft are complex machines designed and built to precise specifications. In many cases, the proper and reliable operation of these aircraft can be a matter of life and death. Therefore, aerospace engineers rely on nickel-based alloys to provide the required response when encountering specific situations in flight. Here is an overview of how these mixed metals contribute to the aerospace industry.
Nickel Alloys in Gas Turbines
One of the best uses of nickel alloys is in gas turbines in aircraft engines. A turbine is a rotating fan that uses one source of power to produce another source of power, such as a hydroelectric power plant or a wind turbine. Aircraft gas turbines work on the same principle, except that pressurized gas produces the energy needed to rotate the turbine. The thrust generated by the aircraft turbine propels the aircraft forward, off the ground, and into the air.
During World War II, gas turbine engines required frequent maintenance because the high temperatures of the internal combustion engine would quickly corrode the steel alloys. Scientists and engineers turned to nickel alloys, which are heat-resistant and corrosion-resistant, to solve this problem.
Aircraft engineers replaced stainless steel alloys in turbines with nickel alloys, especially in the combustion chamber. In the combustion chamber, fuel injectors release a continuous stream of pressurized air, and flame holders keep the airflow burning throughout the flight-even when there is a lot of wind blowing through the turbine. Because of this continuous flame, the combustion chamber must withstand high temperatures for a long time. Nickel alloys make this possible.
After discovering the value of nickel alloys in gas turbines, aerospace engineers continued to improve the performance of nickel alloys in aircraft flight.
Adding other metals such as tungsten and molybdenum to the alloys makes them more heat-resistant. The use of aluminum-based coatings improves the corrosion and rust resistance of nickel alloys. New alloy casting methods give them the directional strength they need.
Today, about 1.8 tons of nickel alloys are used in a single jet engine. These nickel alloys enable jet engines to complete about 20,000 hours of flight without major repairs. In contrast, before nickel alloys became standard, aircraft had a flight life of only 5 hours, which shows the importance of nickel alloys in the aerospace industry.
Nickel Alloys in Other Aircraft Components
While nickel alloys are best known for improving the efficiency of gas turbines, they are also used in other aircraft components.
80A alloy can retain its shape even under extremely high temperatures and great stress. It is often used in aircraft exhaust valves, which remove hot exhaust gases from the engine.
Monel is another nickel alloy used in aircraft. This metal contains 68% nickel, 29% copper, and small amounts of iron, manganese, and other elements. Monel is similar to steel in many ways, has a high resistance to heavy pressure (i.e. tensile strength), and can be welded. Aircraft exhaust manifolds, carburetor valves and sleeves, and the gears and chains that control the landing gear all use monel alloys. Monel rivets are also used to fasten nickel steel alloys.
Nickel alloys on the Lunar Module
Nickel-based alloys are widely used in the aerospace industry and have even been used on the surface of the moon. In the 1960s, the United States' Apollo program landed 12 astronauts on the moon. To get there, the astronauts used a spacecraft designed specifically for the moon: the Lunar Module (LM).
Many of the black exterior parts of the LM were made of nickel-based alloys, according to the Smithsonian's National Air and Space Museum.
These black parts used a nickel-steel alloy to absorb and reflect solar heat from the LM. With the help of up to 25 layers of aluminum coating on the nickel alloy, the parts also protected the spacecraft from tiny meteoroids.
The nickel alloy used on the LM was very thin: just 0.0021072 mm/0.0000833 inches thick. By comparison, regular aluminum foil is about 0.2 mm/0.0079 inches thick. A sheet of printer paper is typically 0.1 mm/0.0038 inches thick. These very thin sections of the Lunar Module (LM) were mentioned in the 1995 film Apollo 13. In the spacecraft's broadcast to Earth, Jim Lovell (played by Tom Hanks) says, "In some places the LM's skin is only a few layers of tinfoil thick, and that's all we have to protect us from the vacuum of space."
Nickel alloys are obviously important to the history of aerospace. Without these heat-resistant and corrosion-resistant metal alloys, we wouldn't be able to cross oceans so easily today, and humans wouldn't be able to walk on the surface of the moon. Needless to say, these nickel-based alloys are indispensable metals for the modern age.
