Titanium << ty TAY nee uhm >> is a strong, lightweight, silver-gray metallic element. Titanium metal has a higher strength-to-weight ratio than steel—that is, objects made of titanium are stronger than steel objects of the same weight. Titanium resists corrosion (chemical breakdown) caused by seawater and sea air as well as platinum does and better than stainless steel does. Many highly corrosive acids and bases do not harm titanium. Machine parts made of titanium can withstand operating temperatures up to about 800 °F (430 °C). However, the uses of titanium are limited because it is expensive to produce. Researchers have worked to develop cheaper methods of producing the metal for widespread use.
Titanium’s chemical symbol is Ti. Its atomic number (number of protons in its nucleus) is 22. Its relative atomic mass is 47.867. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most stable isotope (form) of carbon. Titanium has a density of 4.51 grams per cubic centimeter, higher than that of aluminum but lower than that of stainless steel. Titanium melts at 1668 °C and boils at 3287 °C. Chemists classify titanium as a transition metal . For information on the position of titanium on the periodic table, see the article Periodic table .
Element, Chemical (table: Table of the elements)
Titanium serves as an important element in alloys (combinations of two or more metals). Manufacturers use lightweight, heat-resistant titanium alloys in jet and rocket engines and aircraft and spacecraft bodies. Ship and submarine parts made of titanium alloys can operate in saltwater for long periods without corroding. Titanium alloys are also used in artificial knee and hip joints, pacemakers, and other durable, corrosion-resistant devices designed for use inside the body. In addition, alloys of the metal are used to make durable, lightweight tools, surgical instruments, armor plating, steam-turbine blades, and golf clubs, bicycles, and other sporting equipment.
Compounds that contain titanium are used in the making of many products. Titanium dioxide (TiO2) serves as a strong, bright-white pigment in paint. Manufacturers also use titanium dioxide in floor coverings, paper, plastics, porcelain enamels, rubber, sunscreen, and welding rods. Jewelers cut and polish titanium dioxide crystals to make a gemstone called titania. Titania shines brighter than diamond but is not as hard. Crystals of barium titanate (BaTiO3) are used in television sets and radar and sonar equipment. Other titanium compounds catalyze (stimulate) the chemical reactions that produce the plastic materials polyethylene and polypropylene.
Titanium ranks as the ninth most abundant element in Earth’s crust. It never appears naturally in metallic form because it bonds to oxygen readily and strongly. It often occurs in the ores ilmenite and rutile. Ilmenite is mined mainly in Australia, Canada, India, Malaysia, Norway, South Africa, Ukraine, and the United States. Rutile is mined mainly in Australia and South Africa.
Japan, Kazakhstan, Russia, Ukraine, and the United States produce most of the world’s refined titanium metal. China also makes titanium.
William Gregor, an English clergyman and mineralogist, discovered titanium, in the form of titanium dioxide, in 1791. The German chemist Martin H. Klaproth independently discovered the element in 1795 and named it titanium. The New Zealand-born American chemist Matthew A. Hunter produced the first pure titanium in 1910. Large amounts of pure titanium were not produced until the 1950’s, after the Luxembourg-born inventor Wilhelm J. Kroll developed a method for extracting the metal from ilmenite. In the Kroll process, ilmenite is treated with chlorine and carbon to produce a colorless, corrosive liquid called titanium tetrachloride (TiCl4). The liquid reacts with molten magnesium to produce titanium metal. In 1948, companies began using the Kroll process to produce the metal for commercial use.
See also Alloy (Alloys for strength and lightness) ; Ilmenite ; Rutile .
