Titanium is a metal chemical element, chemical symbol Ti, atomic number 22, located in the fourth period, IVB group in the periodic table of chemical elements . It is a silver-white transition metal characterized by light weight, high strength, metallic luster , and resistance to wet chlorine corrosion. But titanium cannot be used in dry chlorine. Even dry chlorine at a temperature below 0°C will undergo a violent chemical reaction to form titanium tetrachloride, which will then decompose to form titanium dichloride, or even burn. Only when the water content in the chlorine gas is higher than 0.5%, the titanium can maintain reliable stability in it.
Titanium is considered a rare metal because it is scattered in nature and difficult to extract. But it is relatively rich, ranking tenth among all elements. Titanium ore mainly includes ilmenite and rutile, which are widely distributed in the crust and lithosphere . Titanium is also present in almost all living things, rocks, water bodies and soil. The Kroll method or Hunter method is required to extract titanium from the main ore . The most common compound of titanium is titanium dioxide , which can be used to make white pigments. Other compounds include titanium tetrachloride (TiCl 4 ) (used as a catalyst and used to make smoke screens for air cover) and titanium trichloride (TiCl 3 ) (used to catalyze the production of polypropylene ).
The discovery of titanium
1. Gregor [2] (Reverend William Gregor, 1762—1817): In 1791, titanium was discovered in Cornwall, England in the form of titanium-containing minerals. The discoverer was the English amateur mineralogist Gregor ( Reverend William Gregor, who was working as a priest in charge of the parish of Creed in Cornwall. He found some black sand by the creek in the neighbouring Manaccan parish. Later, he discovered that the sand would be attracted by magnets. He realized that this mineral (ilmenite) contains a new element. . After analysis, it was found that there were two metal oxides in the sand: iron oxide (the reason the sand is attracted by the magnet) and a white metal oxide that he could not identify. Realizing that this unidentified oxide contains an undiscovered metal, Gregor published the discovery to the Royal Geological Society of Cornwall and the German Annals of Chemistry. At about the same time, Franz-Joseph Müller von Reichenstein produced a similar substance, but could not identify it.
2. Klaproth [3] (Martin Heinrich Klaproth, 1743-1817): In 1795, the German chemist Klaproth also discovered this oxide when analyzing red rutile produced in Hungary. He advocated adopting the method of naming uranium (discovered by Kraprot in 1789), citing the name of the Titanic tribe in Greek mythology , "Titanic", to name this new element "Titanium". The Chinese name is named Titanium according to its transliteration. When he heard of Gregor's earlier discovery, Klaprott obtained some samples of the Manacán mineral and confirmed that it contained titanium.
3. Hunter [4] (Matthew A. Hunter): The titanium discovered by Gregor and Kraprot was powdered titanium dioxide, not metallic titanium. Because the oxide of titanium is extremely stable, and metal titanium can directly and fiercely combine with oxygen, nitrogen, hydrogen, carbon, etc., elemental titanium is difficult to prepare. It was not until 1910 that the American chemist Hunter used sodium to reduce TiCl 4 to produce titanium with a purity of 99.9%.
Development history abroad
In 1940, Luxembourg scientist WJKroll used magnesium to reduce TiCl4 to obtain pure titanium. Since then, the magnesium reduction method (also known as the Kraul method) and the sodium reduction method (also known as the Hunter method) have become industrial methods for producing sponge titanium. The United States used the magnesium reduction method to produce 2 tons of sponge titanium in 1948, and the industrial production of titanium began.
In 1947, people began to smelt titanium in factories. That year, the output was only 2 tons. Production surged to 20,000 tons in 1955. In 1972, the annual output reached 200,000 tons. The yield strength of titanium is higher than that of steel, and its weight is almost half of the same volume of steel. Although titanium is slightly heavier than aluminum, its yield strength is twice that of aluminum. The specific strength of titanium is higher than that of aluminum and steel, and the specific modulus is very close to that of aluminum and steel. In space rockets and missiles, large amounts of titanium are used instead of steel. According to statistics, the world's annual titanium used for space navigation has reached more than 1,000 tons. Very fine titanium powder is also a good fuel for rockets, so titanium is known as cosmic metal and space metal.
Titanium easily reacts with air at high temperatures, but its melting point is as high as 1668°C. At normal temperature, titanium is not afraid of corrosion by aqua regia and dilute nitric acid, but it is not resistant to corrosion by sulfuric acid and 7% hydrochloric acid with a concentration of more than 5%. Titanium is not afraid of seawater at room temperature. Someone once sunk a piece of titanium to the bottom of the sea, and took it up five years later. There were many small animals and seabed plants stuck on it, but there was no rust at all, and it was still shiny.
People began to use titanium to make submarines-titanium submarines. Because titanium is very strong and can withstand high pressure, this submarine can sail in deep seas up to 4,500 meters deep.
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