As a material scientist, you’ll work with various materials, from composites and polymers to inorganic metals. While there are many jobs in the aerospace industry, and each may require knowledge of different materials, here are five materials you will be familiar with as an aerospace engineer.
An aerospace engineer should be familiar with aluminum alloy parts because of their great properties. The process of aluminum alloy fabrication is called “casting.” In casting, solid aluminum blocks are either shaped by mechanical means or melted and poured into molds. These molten blocks are then allowed to cool, solidify, and cut for the final product.
Aluminum alloy has a density of 6.7 g/cm³, making it lightweight and strong. Aluminum is also corrosion-resistant and can withstand extreme heat. For this reason, it’s used in aircraft and spacecraft for antennae and other electronic equipment. In addition, AMS 3195 Silicone is used to seal aluminum alloys in space.
The silicone gets rid of any oxygen that may be trapped in the metal. This is important because when aluminum is exposed to air, it forms a layer of aluminum oxide on the exposed parts of the metal.
Titanium has the same properties as aluminum alloy, from lightweight and strong to corrosion-resistant. However, titanium alloy is stronger than aluminum and lighter than steel.
Titanium alloys are cast from molten titanium, which is then allowed to cool in a mold, usually created by sand or permanent-mold casting. Titanium alloys have a density of 7.9 g/cm³ and are resistant to corrosion. Titanium is preferred for aircraft and spacecraft because of its lightweight and strong properties. Military aircraft and spacecraft are usually made out of titanium alloy because the lighter titanium alloys reduce the weight the aircraft must carry, and their strength makes them more durable than aluminum alloys.
Aerospace engineers are familiar with ceramic components because ceramics are more resistant to heat and can withstand higher temperatures than aluminum alloy and titanium withstanding. Because of the low thermal conductivity of ceramics, they’re also used in heat shielding on spacecraft. But because they have a low strength compared to other materials, they’re used as coatings or linings instead of structural parts.
Ceramics are made by mixing a powder and liquid and then firing it at extremely high temperatures. The firing process isn’t necessarily done in a chamber but can take place in an oven or kiln to maintain a constant temperature. The temperature is usually above 1500 ˚C but no higher than 1800 ˚C.
Carbon Fiber Composite
Carbon fiber-reinforced plastic is a lightweight material stronger than steel but has a lower density (2.9 g/cm³). It’s used for structural parts on aircraft and spacecraft because of its strength and low weight. Carbon fiber composites are made by putting layers of fabric together with a matrix material such as epoxy resin or thermoset resin to act as an adhesive.
The fibers of carbon fiber are woven together to create a network that adds strength to the material, while the resin filler adds stiffness to the final product. According to NASA, only the thermoset resin is toxic during production. Once the carbon fiber composite is created, it’s then impregnated with a resin that hardens on exposure to heat, light, or a catalyst.
Cured polymer is a polymer that has been reacted with a curing agent, making it hard and rigid. It’s mostly used in spacecraft as electronic equipment and mechanical parts housings. Because of its low thermal conductivity, it also acts as a heat shield for electronic components on spacecraft.
Polymers are made by mixing monomers in the presence of a catalyst, which may be an acid or base. This can be done on an industrial scale to produce meters of polymer or on a laboratory scale to produce only small quantities at a time. The polymer can then harden, solidify, or “cure.” Depending on the polymer, the curing process can take over a few hours or up to several days.
Aerospace engineers must know all these materials because no single structure is made entirely of just one material. Some materials are combined because they each have specific properties that make them strong in the areas where others are weak. Other materials are used together to get the best out of each material.