Two different metallic materials used in components in the aerospace industry
Titanium support structure for a jet engine
Aircraft engines, especially for jets, have primarily been constructed of metallic components from various titanium and aluminum alloys. Titanium alloys are used in aerospace applications for their unique characteristics: weight reduction (as substitute to steels and Nickel-based super alloys); application temperature (as substitute for aluminum alloys, nickel-based super alloys, and steels); corrosion resistance (as substitute to aluminum alloys & low-alloyed steels); galvanic compatibility in polymer matrix composites (as substitutes for aluminum alloys); and space limitation (as substitute to aluminum alloys and steels) (Verlinden & Cahn 2007, p.56). As such, titanium a metallic material of choice for jet engines where the combination of weight, strength, high temperature stability of aluminum, corrosion resistance, nickel-based super alloys, or high strength steels are insufficient. Titanium is the second most commonly used material in jet engines after Nickel-based super alloys on structural weight consideration; and in terms of volume, titanium is the most abundant material found in jet engines (Lehmhus 2013, p.89).
Titanium alloys are used considerably more in the engine bay of modern military fighter aircrafts as compared to commercial aircraft engines. The greater use in military fighter aircraft is mainly due to need to design the engine to response to higher thermal and mechanical loads typical of supersonic cruise speed and greater maneuverability of the jets (Lütjering & Williams 2003). Titanium is well-suited to cope with the aero kinetic heating on the engine’s surface skin where temperatures can rapidly the capability of aluminum alloys. A newer alloy of titanium, Ti-6Al-2Zr-2Sn-2Cr-0.25Si, is currently used in the engine bay bulkheads of the US F-22 and Joint Strike Fighter projects.
Metallic cover of the flight recorder box
The flight recorder box is designed to withstand extreme heat, violent plane crashes as well as immense pressure. The covering or outer armor of the flight recorder box is made out of heavy, stainless steel shell (Leyens & Peters 2003, p.78). This high temperature insulation material is often about 0.25 inches (or 0.64cm) thick. An aircraft usually has a couple of stainless steel shells with a heat-protective material between them. The stainless steel case has the ability to withstand extreme temperatures as high as 2,000°F (1,100°C) for about half an hour when the plane bursts into flames after a crash. The heavy stainless steel covering also serves to enable the flight recorder box to withstand pressure experienced at 6,000 meters (or 20,000 feet) underwater for 30 days (Science and Technology Department Carnegie Library of Pittsburgh 2002, p.145). The covering of the flight recorder box can also be made of titanium. Both stainless and titanium are only best suited for the black box and other components as opposed to being used to construct the entire plane because of their weight and high cost.
Bibliography:
LEHMHUS, D. (2013). Structural materials and processes in transportation. Wiley-VCH.
LEYENS, C., & PETERS, M. (2003). Titanium and titanium alloys fundamentals and applications. Weinheim, Wiley-VCH.
LÜTJERING, G., & WILLIAMS, J. C. (2003). Titanium. Berlin [u.a.], Springer.
Science and Technology Department Carnegie Library of Pittsburgh. (2002). The handy science Answer Book. Detroit: Visible Ink Press.
VERLINDEN, B., & CAHN, R. W. (2007). Thermo-mechanical processing of metallic materials. Amsterdam, Pergamon.
