1. Discovery and naming of titanium
In 1791, an English clergyman and mineralogical enthusiast, H. W. Gregor, first discovered the titanic-iron mixed oxide black magnetic sand (FeTiO3) from titanore and realized that the mineral might include a new element. In 1795, the German chemist M. H. Klaproth independently obtained Titanium oxide from Hungarian rutile and named it Titanium, after the Titans, born of the Greek god of earth.
It was not until 1910 that American chemist M. A. Hunter replaced titanium tetrachloride with metallic sodium with elemental titanium with a purity of 99.9%. This is the 29th element discovered by humans, and its element symbol Ti is composed of the upper case of the first letter and the lower case of the second letter of its Latin name. The Chinese name titanium is a newly created phonetic character based on the transliteration of its Latin name.
2 Physical properties of titanium
The atomic radius (covalent radius) of titanium is 132pm, the ionic radius is 68pm (+4), 76pm (+2), the atomic weight is 47.86, the atomic volume is 10.65cm3/ mol, the density is 4.507g/cm3, the hardness is 4.0°, the melting point is 1660℃, the boiling point is 3287℃. Titanium metal is silver - white, the crystal structure type for metal crystal, hexagonal system. Appearance like steel, the maximum strength, low temperature and high temperature resistance, from -250℃ to 500℃ can maintain high strength, but also wear resistance.
manufacturer Seamless titanium tube manufacturer says pure metal has excellent malleability, strong plasticity, can press pieces and draw wire, but in the presence of impurities it is tough and brittle. Titanium is mechanically three times stronger than aluminum and six times stronger than magnesium, and has virtually no metal fatigue. Compared with steel and copper and other metals or alloys, titanium has the longest attenuation time of its own vibration after being subjected to mechanical vibration and electric vibration. Excellent conductivity and heat transfer, non-magnetic, but at -272.74℃ can become a superconductor. Liquid titanium can dissolve nearly all metals and form alloys with a variety of metals.
3 Chemical properties of titanium
The valence electron configuration of titanium is 3d24s2, the electronegativity is 1.5, the first electron affinity is 37.7kJ/mol, the first ionization energy is 659kJ/mol, the standard electrode is -0.86V, the oxidation number is +4, +3, +2, 0, -1, and the common valence is +3, +4. At room temperature, titanium is relatively stable in air and water, and does not interact with oxygen and halogen, nor is it corroded by dilute acid, dilute alkali and seawater. However, when the temperature rises, the chemical activity increases rapidly. When the temperature is higher than 600℃, it can directly combine with oxygen, nitrogen, carbon, sulfur, halogen and other non-metallic elements. In addition to forming ordinary compounds, it can also form intermetallic compounds, especially volatile and hydrolyzed compounds with chlorine.
In addition, titanium can dissolve in hot hydrochloric acid, sulfuric acid, phosphoric acid and hydrofluoric acid, generating titanium salt. Generally, the greater the concentration of acid, the faster the dissolution rate. Four kinds of hot concentrated organic acid solutions can also attack titanium metal. They are oxalic acid, formic acid, trichloroacetic acid and trifluoroacetic acid. Titanium can also be attacked by aluminum trichloride. The corrosion effect of the above compounds on titanium is mainly due to their ability to erode the extremely fine oxide film on the surface of titanium. The inertness of titanium is due to the protective effect of this oxide film. Oxidizing agents, such as nitric acid, are typically added to corrosive fluids to slow their corrosion of titanium, since oxidizing agents passivate the surface of titanium by regenerating oxide films. In powder form, titanium is reactive and burns in the air.
4 Preparation of titanium
Titanium has a strong affinity for oxygen, nitrogen and hydrogen at elevated temperatures, so it cannot be extracted directly from its oxides by reduction reaction. The extraction of titanium from primary ores is done using either the Crol or Hunter process, and the equation is as follows:
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(Vacuum distillation at 1000℃ to remove Mg and MgCl2, arc melting ingot)
There are four main steps in titanium treatment:
① The titanium ore is reduced to "cavernosum" (a breathable form);
(2) To make ingots, melt the sponge body (or use the sponge body plus an aluminum alloy) to form ingots;
(3) Preliminary manufacturing, the ingot into general mechanical products, such as billet, rod, plate, sheet, strip and pipe;
(4) Processing and manufacturing, additional processing and forming of mechanical products.
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5 Uses of titanium
(1) Warships and submarines made of titanium are not magnetic, will not be detected and tracked by magnetic mines, and can resist deep water pressure, and can sail in a depth of up to 4500m, which is beyond the reach of ordinary submarines.
(2) Using the toughness, elasticity and corrosion resistance of titanium steel alloy, can be made of ship shell and submarine, using titanium steel alloy specific strength characteristics and extreme temperature resistance (at 550℃ still has great strength), can be made of aircraft, tanks, rockets, satellites and spacecraft. It is estimated that 59 terts of titanium are used to make a Boeing 777, 44 terts for a 747 and 18 starts for a 737.
③ Using the characteristics of hydrogen absorption at normal temperature and hydrogen discharge at elevated temperature, iron titanium alloy can be used as a tiny hydrogen storage warehouse, easy to use. Moreover, it can be used as getter in the manufacture of vacuum tubes and picture tubes, as a hydrogen source in the manufacture of metal foams, and in powder metallurgy and cermet sealing.
(4) The "best shape memory alloy" made of the same amount of titanium nickel has strong shape memory resilience, better recovery ability and higher memory life. It is commonly used in the antenna of the spacecraft, the connecting parts of the pipeline, and also used in the manufacture of medical instruments, electrical instruments and robots, and also used in orthopedic treatment and medical orthopedic treatment.
⑤ Piezoelectric ceramics made of barium titanate, lead titanate, lead praseodymium titanate and other materials can convert mechanical energy into electric energy, which can be used in piezoelectric lighters, mobile X-ray power sources and explosive devices; it can also convert electrical energy into ultrasonic vibration, which can be used for underwater fish hunting, ultra-cleaning ultrasonic medicine and non-destructive detection of metals, and is widely used in automation equipment.
⑥ Titanium is known as "biophile metal", it itself is non-toxic, can also resist the corrosion of human secretions, and can get along nicely with human skin, muscles and bones, although it is a foreign body, but does not cause immune reaction. In medical treatment it is commonly used as artificial bones, liquid titanium can also be used to repair damaged bones.
⑦ Pure titanium dioxide is a kind of fine pigment commonly known as "titanium white", and titanium dioxide photocatalyst is a kind of nano-scale active material, coated on the surface of the substrate after drying will form a film, under the action of light it will produce a strong catalytic degradation function, can effectively degrade toxic and harmful gases in the air.