Why is titanium said to be the metal of the future?
In 1791, HW Gregor, a British priest and mineralogy enthusiast, first discovered black magnetic sand (FeTiO3), a mixed oxide of titanium and iron, from ilmenite ore. He realized that the mineral might contain a new element. In 1795, German chemist MH Klaproth independently prepared titanium oxide from Hungarian rutile and named it "titanium" after the giant "Titan" born from the god of earth in Greek mythology. It was not until 1910 that American chemist MA Hunter replaced titanium tetrachloride with metallic sodium to obtain elemental titanium with a purity of 99.9%. This is the 29th element discovered by humans, and its Latin name is also the first. The second lowercase letter forms its element symbol Ti. The Chinese name titanium is a new phonetic character specially created by my country based on the transliteration of its Latin name.
of 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°, and the melting point is 1660 ℃, boiling point 3287℃. Titanium metal is silvery white, and its crystal structure type is metallic crystal and hexagonal crystal system. It looks like steel, has the highest specific strength, is resistant to both low and high temperatures, can maintain high strength in the range of -250°C to 500°C, and is also wear-resistant. Pure metal has good ductility and plasticity, and can be pressed into plates and wires. However, when impurities are present, it becomes hard and brittle. The mechanical strength of titanium is very high, 3 times that of aluminum and 6 times that of magnesium, and there is almost no metal fatigue. After titanium metal is subjected to mechanical vibration or electrical vibration, its own vibration has the longest attenuation time compared with steel, copper and other metals or alloys. It has good electrical conductivity and heat transfer properties, is non-magnetic, but can become a superconductor at a low temperature of -272.74°C. Liquid titanium dissolves almost all metals and can form alloys with many metals.
Chemical properties of titanium
The valence electron configuration of titanium is 3d24s2, electronegativity 1.5, first electron affinity 37.7kJ/mol, first ionization energy 659kJ/mol, standard electrode potential -0.86V, oxidation number 4, 3, 2, 0, -1. Common valence states 3 and 4 At room temperature, titanium is relatively stable in air and water, does not interact with oxygen and halogens, and is not corroded by dilute acids, dilute alkali and seawater. However, when the temperature increases, chemical activity increases rapidly. When the temperature is higher than 600°C, it can directly combine with various non-metallic elements such as oxygen, nitrogen, carbon, sulfur, and halogen. In addition to the formation of ordinary compounds, interfilling compounds can also be formed, especially volatile and easily hydrolyzable compounds with chlorine.
In addition, titanium is soluble in hot concentrated hydrochloric acid, sulfuric acid, phosphoric acid and hydrofluoric acid to form titanium salts. Generally speaking, the greater the acid concentration, the faster the dissolution rate. Four hot concentrated organic acid solutions can also corrode titanium metal. They are oxalic acid, formic acid, trichloroacetic acid and trifluoroacetic acid. Titanium can also be corroded by aluminum trichloride. The corrosion effect of the above compounds on titanium is mainly due to their ability to corrode the extremely fine oxide film on the surface of titanium. The inertness of titanium is due to the protective effect of this oxide film. Adding nitric acid and other oxidants to the corrosive solution can generally slow down their corrosion of titanium, because the oxidants can regenerate the oxide film and passivate the titanium surface. Titanium powder is very reactive and can burn in the air.
Titanium extraction
Metal titanium has a strong affinity with oxygen, nitrogen, and hydrogen at high temperatures, so titanium cannot be directly extracted from its oxides through reduction reactions. Extracting titanium from the host ore requires the Kroll or Hunter processes. The reaction equation is as follows:
(1000℃ vacuum distillation to remove Mg and MgCl2, arc melting ingot)
There are four main steps in processing titanium metal:
Restore titanium ore into a "sponge" (breathable form);
To make ingots, melt the sponge body (or add intermediate alloy to the sponge body) to form an ingot;
Preliminary manufacturing, converting steel ingots into general mechanical products such as billets, bars, plates, sheets, strips, and pipes;
Processing, manufacturing, deep processing and forming of mechanical products.
major uses of titanium
①Warships and submarines made of titanium are non-magnetic and will not be detected and tracked by magnetic mines. They are able to withstand deep water pressure and can sail to a depth of 4,500 meters that ordinary submarines cannot reach.
②Using the toughness, elasticity and corrosion resistance of titanium steel alloy, ship hulls and submarines can be made, and the high specific strength and high temperature resistance of titanium steel alloy (still having great strength at 550℃ high temperature) can be used to build aircraft. , tanks, rockets, satellites and spacecraft. It is estimated that the production of a Boeing 777 requires 59 tons of titanium, the production of a Boeing 747 requires 44 tons of titanium, and the production of a Boeing 737 requires 18 tons of titanium.
③Using the characteristics of iron-titanium alloy to absorb hydrogen at room temperature and release hydrogen at high temperature, it can be used as a small hydrogen storage warehouse for easy access. In addition, it can be used as a getter in electron tube and picture tube manufacturing, a hydrogen source in foam metal manufacturing, and as a seal for powder metallurgy and cermets.
④The "best shape memory alloy" made of equal parts titanium and nickel has strong shape memory strain capacity, good recovery ability and long memory life. Commonly used in spacecraft antennas and pipe connection components. It is also used in the manufacture of medical equipment, electrical equipment, manipulators and robots, as well as orthopedic treatments and medical orthopedics.
⑤ Piezoelectric ceramics made of barium titanate, lead titanate, lead praseodymium titanate and other materials can not only convert mechanical energy into electrical energy, but are also used in piezoelectric lighters, mobile X-ray power supplies and artillery detonation devices; they can also convert mechanical energy into electrical energy. Electrical energy is converted into ultrasonic vibrations, which are used to explore underwater fish, ultrasonic cleaning, ultrasonic medical and non-destructive testing of metals. Also widely used in automation equipment.
⑥Titanium is called a "biophilic metal". It is non-toxic and resistant to corrosion by human secretions. It gets along well with the body's skin, muscles, muscles and bones. Although it is a foreign body, it does not cause an immune response and is often used as artificial metal in medicine. For skeletal uses, liquid titanium can also be used to repair damaged bone.
⑦Pure titanium dioxide is an excellent pigment commonly known as "titanium white", and titanium dioxide photocatalyst is a nanoscale active material. It is coated on the surface of the substrate and dried to form a thin film, which produces a strong catalytic effect under the action of light. The degradation function can effectively degrade toxic and harmful gases in the air.
