Titanium: abundant in nature, expensive to produce

Titanium oxide was first discovered in 1791 by English scientist William Gregor. When studying iron-bearing sand sampled on a Cornwall beach, the mineralogist isolated a previously unknown compound to which he gave the name “menachanite earth.” Several years later German chemist Martin Heinrich Klaproth, during experiments, discovered the oxide of a new metal and named it “titanium.” The pure metal was discovered only in 1825 by Swedish scientist Jöns Jacob Berzelius.

Properties of titanium

Titanium is the 22nd element of D. I. Mendeleev’s table of chemical elements. In appearance it resembles steel and aluminum. It has a melting temperature of 1,664…1,672°C and boiling temperature of 3,330°C. It is distinguished by elevated resistance to aggressive environments and high-temperature effects, as well as good strength and ductility.

Ti is a paramagnet: it has the ability to magnetize in the presence of an external magnetic field while retaining magnetic permeability below one. But unlike similar materials, as temperature increases titanium’s magnetic susceptibility does not decrease but increases.

Titanium is considered the fourth metal by abundance in the Earth’s crust, after iron, aluminum, and magnesium. But despite its abundance it has high cost. This is due to large costs of obtaining pure metal from ore, because in nature Ti occurs only as oxides and dioxides.

Pure metal welds and cuts very poorly, and chips and dust remaining after processing billets easily ignite at temperatures above 390…400°C. But despite this, the material is widely used in various industries.

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Methods of obtaining

The mass fraction of titanium in the Earth’s interior according to geologists’ estimates is about 0.57–0.58%, most of which is in the basalt shell and granite rocks. Main metal deposits are located in Japan, the USA, Canada, the United Kingdom, France, Belgium, Italy, and Spain. But at all deposits Ti is mined exclusively as titanium ores from which pure metal is then obtained by one of the following methods:

• electrolytic — under high-current effects titanium chlorides and dioxides are separated into elements, making it possible to obtain pure Ti;
• hydride-calcium — metallic calcium is first saturated with hydrogen (H) and mixed with titanium dioxide, then in an airless space under high temperatures the hydride obtained is divided into Ti and H, while washing excess impurities from it with hydrochloric acid;
• magnesium-thermal — first the mined titanium ore is processed into dioxide, which is then chlorinated and reduced using magnesium; after that the alloy obtained is heated to 800°C and gradually cooled to 600°C: during the reaction all impurities evaporate and pure spongy titanium with many pores and voids remains; to obtain industrial metal it is subsequently remelted;
• iodide — this method implies treating Ti dioxide with I (iodine) vapors with subsequent purification of the composition obtained by high-temperature effects.

To obtain titanium of the highest quality the iodine method of metal reduction is used. Other methods of processing titanium ore make it possible to manufacture only technical Ti.

Applications of titanium in industry

Thanks to high service properties and low mass, titanium (both pure and as alloys) has found wide use in many industrial areas, including:

• in aviation and rocket building — to manufacture parts of complex configuration, engine elements, and other heavily loaded assemblies;
• in machine building — both when releasing serial specialized equipment and when assembling units to individual orders;
• in shipbuilding — when equipping pipelines and as ship skin elements;
• in the food industry — when manufacturing industrial-household equipment and kitchenware (it became widespread thanks to high sanitary and hygienic characteristics);
• in medicine — when creating prostheses and producing surgical instruments.

In non-ferrous metallurgy titanium is used both as pure metal and as part of many precision alloys. It is produced as cold-rolled strip, sheets and bars, rounds, tubes, wire, or thread.