Typical Products and Uses of Titanium
Due to Titanium’s amazing properties such as corrosion resistance, high strength-to-weight ratio, low density, high heat resistance, high fatigue resistance, high crack resistance and biocompatibility; it is widely used in various industries (Moiseyev, 2006). Titanium is often combined with other metals such as aluminum, vanadium, copper, iron, manganese and molybdenum to create alloys of improved grain size and hardness (Clifford, 1968). Titanium mill products: titanium foil, sheet, wire, and rod are useful in the aerospace, marine, military and other industries. Titanium powder is also used in pyrotechnics to produce silver sparks (Helmenstine, ...view middle of the document...
In particular, titanium alloys are used to produce aerospace components like critical structural parts, fire walls, landing gear, exhaust ducts (helicopters), and hydraulic systems. The SR-71 "Blackbird" was one of the first aircrafts to make extensive use of titanium within its structure. An estimated 59 metric tons (130,000 pounds) are used in the Boeing 777, 45 in the Boeing 747, 18 in the Boeing 737, 32 in the Airbus A340, 18 in the Airbus A330, and 12 in the Airbus A320. The Airbus A380 may use 77 metric tons, including about 11 tons in the engines (Sevan, 2006). In engine applications, titanium is used for rotors, compressor blades, hydraulic system components, and nacelles. The titanium 6AL-4V alloy accounts for almost 50% of all alloys used in aircraft applications (Donachie, 1988), so the research focuses on this specific alloy. Titanium Ti–6Al–4V alloy is the most important and widely used titanium alloy because of their high strength to weight ratio, good corrosion resistance, excellent fracture toughness and attractive mechanical properties which make it an ideal choice for many aerospace applications. (Venkateswarlu, et. al.,2013)
Processes appropriate for the material
Unlike other compounds, pure titanium cannot be extracted by simply reducing its dioxide since it reacts with oxygen at high temperatures (Stwertka, 1988). The extraction and processing of titanium metal occurs in 4 major steps: reduction of titanium ore into sponge; melting of sponge, or sponge plus a master alloy to form an ingot; primary fabrication, where an ingot is converted into general mill products such as billet, bar, plate, sheet, strip, and tube; and secondary fabrication of finished shapes from mill products (Donachie, 1988).
Titanium may be extracted and processed through different processes, but the two most widely used are the Kroll Process and FFC Cambridge process.
Kroll Process is a complex and expensive batch process developed in 1946 by William Justin Kroll. The expensiveness of titanium is mainly due to its processing (if Kroll process was used), which makes use of the expensive magnesium metal. In the Kroll process, the oxide is first converted to chloride through carbochlorination, whereby chlorine gas is passed over red-hot rutile or ilmenite in the presence of carbon to make titanium chloride TiCl4. This is condensed and purified by fractional distillation and then reduced with 800 °C molten magnesium in an argon atmosphere (Columbia Encyclopedia, 2000-2006). It may be summarized in the following equation: 2Mg(l) + TiCl4(g) → 2MgCl2(l) + Ti(s) [T = 800-850 °C]. The resulting porous metallic titanium sponge is purified by leaching or heated vacuum distillation. The sponge is jackhammered out, crushed, and pressed before it is melted in a consumable electrode vacuum arc furnace. The melted ingot is allowed to solidify under vacuum. It is often remelted to remove inclusions and ensure uniformity. These melting steps add to the cost of...