Titanium is a silvery-white metal valued for its strength, light weight, and resistance to corrosion. Its unique and desirable properties have led to its use in numerous industries and applications, primarily in the aerospace, automotive, medical and chemical processing industries. Titanium is available in a variety of grades and alloys, with each alloy type offering unique properties suitable for specific applications. This article will define titanium and describe its properties, discuss its different grades and alloys, and explain titanium's applications.
What is titanium?
Titanium is a silver-white metal with an atomic number of 22. It is a lightweight, ductile, strong, corrosion-resistant, biocompatible metal with a high strength-to-weight ratio. Titanium is the ninth most abundant element on Earth. It is commonly found in rocks, clay, and sand. Rutile and ilmenite are the two main commercial minerals used to extract and refine titanium. Titanium is divided into α alloy, β alloy and α-β alloy. Titanium alpha alloys are alloyed only with oxygen and often with other metals such as aluminum, molybdenum and vanadium. The addition of these metals helps achieve desired properties such as increased strength, corrosion resistance and reduced weight. Common applications for titanium and its alloys include: commercial and aerospace applications, power plant condensers, desalination plants, marine applications, construction products, medical implants such as joint replacement hardware, and consumer products such as golf clubs and bicycle frames.
What is the origin of titanium?
Titanium was discovered by the British chemist and mineralogist William Gregor in 1791 and named by the German chemist Martin Heinrich in 1795. Klapoulos named this element "titanium" after the Titans in Greek mythology. However, pure titanium was not available until 1910. MA Hunter, a scientist at Rensselaer Polytechnic Institute, separated the metals by heating titanium tetrachloride (TiCl4) with sodium at high pressure and temperature (1292-1472 °F), producing pure titanium and sodium chloride as byproducts. Then, in 1932, William Justin Kroll isolated titanium by fractionally reducing TiCl4 with calcium, followed by magnesium and sodium. Today, the "Kroll process" is the process commonly used for commercial production of titanium.
What is another term for titanium?
Titanium is sometimes called the "wonder metal" or "aerospace metal" because it has many properties required for aerospace applications. Titanium's low density, ductility, tensile strength and corrosion resistance all contribute to its nickname.
What is the chemical symbol for titanium?
The chemical symbol for titanium is "Ti".
What is titanium made of?
Because titanium readily reacts with oxygen, pure titanium is not found in nature. Instead, titanium is found in nearly all rocks, clays, sands, and minerals on Earth in the form of titanium dioxide. Rutile and ilmenite are the two main minerals used in the commercial production of titanium. Anatase, perovskite, brookite, and titanite also contain titanium. Each of the above minerals can be refined to obtain pure titanium.
How is titanium made?
The Kroll process is the most common method for producing pure titanium. The process begins by heating an ore such as rutile or ilmenite to produce liquid titanium tetrachloride (TiCl4). The TiCl4 liquid is then purified by fractional distillation (similar to the fractionation process used to produce gasoline from crude oil). After distillation, molten magnesium is added to liquid TiCl4 to form a porous titanium "sponge" and magnesium-based salt. The titanium sponge is then compressed and melted in an electric arc furnace. Finally, pure titanium is cast into ingots. Alloys can be made by mixing a melt of pure titanium with other metals and then casting it into ingots.
What are the main characteristics of titanium?
Titanium's properties and characteristics vary by grade and specific alloy. However, some general properties of titanium are shown in the table below:
Corrosion Resistance: Titanium is highly resistant to corrosion from seawater, chlorine, and many other corrosive agents, making it useful for marine and chemical processing applications.
Lightweight: Titanium is less dense than many other metals. It is ideally suited for use in lightweight structures and components in the aerospace and automotive industries.
High Strength: Titanium's strength is comparable to steel. However, due to titanium's lower density, a titanium structure of equal strength weighs approximately 45% less than a corresponding steel structure. Due to its high strength and high strength-to-weight ratio, titanium is commonly used in aerospace, automotive, medical and marine applications.
Biocompatibility: Titanium is considered the most biocompatible metal due to its inertness, resistance to corrosion by body fluids, ability to integrate into bone (osseointegration), and high cyclic fatigue limit. This allows titanium to be used in bone, joint and dental implants.
Heat Resistance: Titanium has a low thermal conductivity. This makes titanium ideal for high-heat applications such as machining, spacecraft, jet engines, missiles and automobiles.
Non-magnetic: Titanium is non-magnetic but becomes paramagnetic in the presence of a magnetic field.
Ductility: Titanium is a ductile metal, and its ductility increases with temperature. Additionally, alloying titanium with other ductile metals such as aluminum can significantly increase its ductility.
Low thermal expansion: Titanium has a low coefficient of thermal expansion. Titanium does not expand or contract under extreme temperatures like other materials such as steel. Its low thermal expansion properties make titanium ideal for structural applications that experience high temperatures, such as aerospace and spacecraft or large buildings and skyscrapers in the event of fire.
Excellent fatigue resistance: Titanium has excellent fatigue resistance. This makes titanium well-suited for aerospace applications, where structural components of aircraft such as landing gear, hydraulic systems and exhaust pipes are subjected to cyclic loads.
What is the color of titanium?
Titanium is silver gray or silver white. However, if anodized in a specific way, titanium can achieve a full spectrum of colors. By controlling the voltage during anodization, different colors of titanium can be obtained.
What does titanium look like?
Titanium is commonly found in igneous and sedimentary rocks and minerals. Ilmenite (iron titanium oxide) and rutile are two minerals from which titanium is commonly extracted. Ilmenite is a gray-black rock, while rutile is a dark brown to black rock with a crystalline appearance.
