Titanium,periodic table of ele mentsThe fourth period is a transition metal element of the fourth group (titanium subgroup), element symbol Ti, atomic number 22, and relative atomic mass 47.867.Titanium is a hard and shiny silver white metal with hexagonal alpha phase and cubic beta phase.The relative density is 4.506, the melting point is 1668 ℃, and the boiling point is 3287 ℃.The resistivity is 42x10 ⁻ ⁸ Ω · m (20 ℃).In naturerutile、perovskite 、ilmeniteAnd so on.Reduction of titanium tetrachloride by magnesium at high temperatureSponge titaniumAnd then the titanium ingot is obtained by arc melting.[1]
Titanium is widely distributed in nature. The content of titanium in the crust is about 0.64%, which is second only to that of metal elementsaluminum, iron and magnesium, ranking fourth.[2]
Titanium is widely used because of its excellent properties.Its application fields mainly include:AerospaceShip manufacturing, chemical and petrochemical industry, transportation, weaponsocean, electric power, construction, metallurgy, medical treatment, sports equipment, daily necessities, light industry, etc.[2]
In 1791, the English priest WGregor found a new metal element in black magnetite.[2]
In 1795, German chemist MH. Klaproth also found this element when studying rutile and named it after the Greek god Titans.[2]
In 1910, American scientist MA. Hunter made pure titanium by reducing TiCI4 with sodium for the first time.[2]
In 1940, Luxembourg scientist WJ. Kroll reduced TiCl4 with magnesium to produce pure titanium.Since then, magnesium reduction method (also known as Crowe method) and sodium reduction method (also known as Hunter method) have become industrial methods for producing sponge titanium.[2]
In 1948, 2t sponge titanium was produced by magnesium reduction method in the United States, which started the industrial production of titanium.[2]
Material structure
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Titanium has an atomic number of 22 and 22 extranuclear electrons. Its electronic configuration is 1s ² 2s ² 2p ⁶ 3s ² 3p ⁶ 3d ² 4s ² ([Ar] 3d ² 4s ²).There are two isomers of titanium: α - Ti and β - Ti.α - Ti is hexagonal crystal system, and the atomic stacking mode is hexagonal close stacking, and the space utilization rate of atoms is 74%.β - Ti is a cubic lattice, and the atomic stacking mode is body centered cubic dense stacking. The space utilization rate of atoms is 68%.In addition, when there are a few defects in the titanium crystal, it will affect the properties of the crystal, such as mechanical strength, conductivity, etc.[3]
Physical and chemical properties
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physical property
Titanium wire
The relative density of titanium is 4.506, the melting point is 1668 ℃, and the boiling point is 3287 ℃.The resistivity is 42x10 ⁻ ⁸ Ω · m (20 ℃).Due to the dense oxide on the surface, it is resistant to corrosion. It does not react with oxygen, halogen and water at room temperature, but reacts with oxygen to generate titanium dioxide when it is hot.It does not react with nitric acid, dilute sulfuric acid and alkali, but is soluble in concentrated sulfuric acid, hydrofluoric acid and aqua regia.[1]
Titanium has plasticity. The elongation of high-purity titanium can reach 50-60%, and the reduction of area can reach 70-80%. However, it has low strength and is not suitable for structural materials.The presence of impurities in titanium has a great impact on its mechanical properties, especially interstitial impurities (oxygen, nitrogen, carbon) can greatly improve the strength of titanium and significantly reduce its plasticity.The good mechanical properties of titanium as a structural material are achieved by strictly controlling the appropriate impurity content and adding alloy elements.
chemical property
Reaction of titanium with air
Once titanium starts to burn in the air, it will emit an extremely bright white flametitania(TiO ₂) and titanium nitride (TiN).Titanium metal can even be burned in pure nitrogen to produce titanium nitride.[4]
Reaction of titanium with water
Metal titanium will react with water vapor to form titanium oxide (Ⅳ) (TiO ₂) andhydrogen（H₂）。[4]
Reaction of titanium with halogen
When heated, titanium will react with halogen elements and generate titanium halide (Ⅳ).The reaction with fluorine takes place at about 200 ℃.Titanium and fluorine (F ₂)chlorine(Cl ₂), bromine (Br ₂) and iodine (I ₂) react to produce titanium fluoride (Ⅳ) (TiF ₄), titanium chloride (Ⅳ) (TiCl ₄), titanium bromide (Ⅳ) (TiBr ₄) and titanium iodide (Ⅳ) (TiI ₄), respectively.[4]
Reaction of titanium with acid
Dilute hydrofluoric acid aqueous solution reacts with titanium to generate complex ions and hydrogen (H ₂):
Metal titanium can not react with inorganic acid at room temperature, but can react with hot hydrochloric acid to form titanium (Ⅲ) complexes.[4]
Preparation method
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Titanium alloy rod
Smelting titanium requires complicated steps.Turn ilmenite into titanium tetrachloride, put it into a sealed stainless steel tank, fill it with argon, and make it react with magnesium metal to getSponge titanium。Sponge titanium cannot be used directly. It must be melted into liquid in an electric furnace before it can be cast into titanium ingot.However, this kind of electric furnace requires high technology. In addition to the fact that the air of the electric furnace must be cleaned, it is even more troublesome to find a crucible containing liquid titanium, because ordinary refractory materials contain oxides, and the oxygen in it will be taken away by liquid titanium.Later, people finally invented an electric furnace called "water-cooled copper crucible".Only the central part of the electric furnace is very hot, and the rest is cold. After titanium is melted in the electric furnace, it flows to the wall of the copper crucible cooled with water, and immediately solidifies into titanium ingots.
The method for mass production of titanium in industry is the Kroll process: chlorine and carbon are used toilmenite(TiFeO ≮) or rutile (TiO ₂) to produce metallic titanium.Then distill the obtainedTitanium tetrachloride(TiCl ₄) Same asFerric trichloride(FeCl ∨) separate.Finally, titanium tetrachloride was reduced with magnesium (Mg) to obtain titanium metal.Air should be removed during production to avoid titanium reacting with oxygen or nitrogen to generate impurities.[4]
application area
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Industrial use
Aviation titanium alloy engine
Titanium is widely used because of its excellent properties.Its application fields mainly include: aerospace, ship manufacturing, chemical and petrochemical industry, transportation, weapons, ocean, electricity, construction, metallurgy, medical treatment, sports equipment, daily necessities and light industry.Most titanium processing materials in the United States and Russia are used in the aerospace field, accounting for about 80%. On the contrary, Japan and China use 80% of them in the chemical industry, general civil industry and household goods.From the perspective of the world's demand for titanium, the structural proportion in 2005 is: aerospace accounts for 35%, military accounts for 12%, industrial accounts for 38%, and civil and other accounts for 15%.[2]
In the weapons industry, titanium is used in tanks, chariots, missiles, large and small gun bodies, machine guns, flamethrowers, helmetsBulletproof vests, explosion-proof gloves, etc.[2]
In the metallurgical industry, titanium is used in: corrosion resistant containersElectrolytic cell, reactors, concentrators, separators, heat exchangers, coolers, various pumps and valves, turbine blades, connecting piping, accessories, etc.[2]
In offshore engineering, titanium is used to:Seawater desalinationOffshore oil drilling, marine thermal energy conversion power station.[2]
In terms of sports equipment, titanium is used for: golf clubs, ball heads, tennis rackets, fencing protective masks, swords, sprint shoes, climbing tools, skis, ski shoes, ski poles, ice skates, diving suits, fishing tackle, tent poles, etc.[2]
In terms of daily necessities, titanium is used to:Spectacle frame, watches, computers, cameras, game consoles, mobile phones, antennas, musical instruments, kitchen appliances, handicrafts, etc.[2]
aviation industry
aviation industryIt is the earliest department to develop and apply titanium and titanium alloys. If there is no titanium for aircraft and engines, it is virtually impossible to produce supersonic aircraft of Ma2.7.Titanium alloy is mainly used in aircraft structure for skeleton, skin, fuselage frame, landing gear, firewall, wing, tail wing, longitudinal beam, hatch cover, multiplier, keel, quick acting brake, parking device, fastener, front wheel, arch frame, flap slide rail, flap, road sign light, signal board, etc.[2]
Aerospace industry
Titanium inAerospace industryIt has also reduced launch weight, increased range and saved costs. It is a popular material in the aerospace industry.In the rocket, missile and aerospace industries, it can be used as pressure vessel, fuel tank, rocket engine shell, rocket nozzle sleeve, artificial satellite shell, manned spacecraft cabin (skin and structural framework), landing gear, lunar module, propulsion system, etc.In addition to industrial pure titanium Ti64 (ELI) and Ti-5Al-2.5Sn (ELI), titanium for aerospace also uses Ti-7Al-4Mo, Ti-3Al-2.5V, Ti-13V11Cr-3Al, Ti-15V-3Cr-3Sn-3Al and Ti/B-Al composites.[2]
Shipbuilding
Titanium and titanium alloys are widely used in nuclear submarines, deep submersibles, atomic energy icebreakers, hydrofoil ships, hovercraft, mine sweepers, as well as propeller propellers, whip antennas, seawater pipelines, condensers, heat exchangers, acoustic devices, and fire-fighting equipment. The main alloys are industrial pure titanium, Ti64, Ti64ELI, Ti-6Al-2Nb-1Ta-0.8Mo, Ti-3Al2.5V, IIT-3B, IIT-7M, etc.[2]
Transport vehicles
Titanium alloy connecting rod
Titanium is widely used in automobiles, mainly including:connecting rod、crankshaft, retaining ring, valve, intake valve, exhaust valve, brake pressure pipe seal ring, rim screw, steering rack and pinion, spring, muffler, exhaust device, wheel bushings and bearings, various half shafts, fasteners, etc.The most outstanding advantages of titanium alloy parts for automobile products are: reducing mass, extending service life, improving reliability, saving fuel, no lead, cobalt and other harmful metals, and greatly improving corrosion resistance and high temperature resistance.[2]
Titanium is mainly used for exhaust pipes, mufflers, sleeves, suspension springs, sprockets, transmission chains and screws on motorcycles.[2]
chemical industry
Titanium materials are used in chemical and petrochemical industries, includingElectrolytic cell(electrode), reactor, concentrator, separator, heat exchanger, cooler, absorber, connecting piping, accessories (flange, bolt, nut), gasket, pump, valve, etc.The industry with the largest titanium consumption in the chemical industry is chlor alkali manufacturing, accounting for 50% of the total titanium consumption, followed by soda ash accounting for 20%, plastics accounting for 17%, organic chemicals accounting for 10%, and inorganic chemicals accounting for 3%.Among various chemical equipment using titanium, heat exchangers account for the most, accounting for 52% of the titanium consumption, followed by anodes accounting for 24%, containers, pipes and pump valves accounting for 19%, and others accounting for 5%.Take heat exchanger, titanium metal anode and wet chlorine cooler as examples to illustrate the advantages of titanium equipment.[2]
Titanium ores mainly include titanium ores, rutile ores and ilmenite placers in vanadium titanium magnetite.[11]The world is rich in titanium resources, with the highest proportion of ilmenite reserves/output.The reserves of titanium on the earth are very rich, the crustal abundance is 0.61%, and the seawater contains 1 × 10 titanium-7Its content is higher than that of common copper, nickel, tin, lead and zinc.According to the data of the United States Geological Survey (USGS), the global titanium reserves in 2022 will be 700 million tons, of which the ilmenite reserves will be 650 million tons, accounting for 92.86%, a decrease of 7.14% over the previous year. Mainly affected by the closure of Australia's old mines, the rutile reserves will be 49 million tons, accounting for 7.54%;In terms of output, the output of ilmenite is 8.9 million tons, accounting for 93.68% of the total output, and the output of rutile is 590000 tons, accounting for 6.21%.[5]
Ilmenite is mainly distributed in Asia, Oceania and Europe, and its domestic reserves rank first.The top five countries with reserves areChina（29.23%）、Australia(24.62%), India (13.08%), Brazil (6.62%) and Norway (5.69%), of which the reserves of China and Australia account for more than half of the global reserves.Rutile is mainly distributed in North America, Africa and Asia, and Australia's reserves account for 63.27%.The top five countries with reserves are Australia (63.27%), India (15.10%), South Africa (13.27%), Ukraine (5.10%) and Mozambique (1.82%).[5]
China's titanium vanadium reserves rank first in the world, accounting for about 70% of the world's total.China's titanium vanadium ore resources are mainly distributed in western regions such as Sichuan, Yunnan and Guangxi, with Panzhihua as the main storage area.Panzhihua has 898 million tons of titanium dioxide reserves, of which 597.8 million tons are on the table, accounting for 93% of the national reserves and 59% of the world reserves.[11]
Safety measures
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Health hazards
In the process of mechanical treatment of titanium metal, it also contacts the smoke and dust of titanium oxide.Titanium tetrachloride used in the production process can make people suffer from chronic bronchitis, chronic hypertrophic rhinitis and pharyngitis.Functional disorder of autonomic nervous system, increased tendon reflex, eyelid and hand tremor, and hyperhidrosis.People exposed to 10% titanium tetrachloride solution have thermal burns that are difficult to heal.[6]
Hazard prevention
Isolate the leakage contaminated area and restrict access.Cut off the ignition source.It is recommended that emergency personnel wear dust masks (full face masks) and gas suits.Do not touch the leakage directly.Small amount of leakage: avoid raising dust and collect it in a dry, clean and covered container with a clean shovel.Transfer recovery.Large amount of leakage: covered with plastic cloth and canvas.Use spark free tools for transfer and recovery.[8]
Toxicological data
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acute toxicity
Titanium, titanium dioxide and titanium carbide belong to the low toxicity category.[8]
Some people used nanometer and micrometer titanium dioxide to conduct experiments to explore its impact on the lungs of mice. After the rats were anesthetized with ether, they were exposed to 0.001mL/g by non exposed tracheal instillation twice a week for four consecutive weeks.In the 32mg/kg nano-TiO ₂ group, the injury was serious, and the alveolar dilatation or occlusion in 40-50% of lung tissue was poor. Macrophages that swallowed brownish yellow foreign particles were commonly seen in the alveolar cavity, the alveolar septum, and the alveolar wall, which were often lumpy. They were also seen in the lumen of small branches of the trachea, and some of them might enter the lymphatics or capillaries. Bronchial epithelium fell off, and lymphocytes, macrophagesFibroblasts increased, the spacing widened, and lymphocyte aggregation nodules were seen.A large number of brown refractive particles were found in the 32mg/kg micrometer TiO ₂ group, which were distributed in the alveolar cavity, wall, and interval, and a few scattered in the respiratory tract of rats. The results showed that the exposure of nano-TiO ₂ to a certain extent could cause the imbalance of antioxidant balance, pathological damage, and changes in ultrastructure of lung tissue in rats, and the oxidation damage of nano-TiO ₂ at the same concentration was more serious than that of micrometer TiO ₂.[9]
Poisoning mechanism
Insoluble titanium such as titanium metal, titanium oxide and titanium carbide has low toxicity, little oral absorption and no toxic reaction.No pathological reaction was found after titanium was implanted into the body.Inhalation of insoluble compounds of titanium has no serious damage to the lungs, and its fibrogenic effect is minimal.Long term feeding of animals with titanium containing water has no effect on growth and development, and no tumor has occurred.
carcinogenicity
The International Agency for Research on Cancer listed TiO ₂ as a suspected human carcinogen in 2006. Its carcinogenicity evaluation mainly depends on the results of animal experiments, lacking sufficient epidemiological evidence.With the expansion of the production scale of TiO ₂ in China and the increase of application industries, the opportunities for occupational groups to contact TiO ₂ have increased dramatically.[10]
Storage and transportation
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Storage method
Titanium is a relatively stable metal, which is not prone to chemical reaction under normal environment.However, in order to ensure its quality and performance, some measures still need to be taken during storage and processing.Wet and passivate with at least 25% water during storage.It is better to store in an environment with relative humidity less than 50%.Titanium is prone to oxidation reaction when exposed to sunlight or ultraviolet light for a long time. Therefore, direct sunlight or ultraviolet light should be avoided as far as possible to maintain its surface luster and quality.Titanium is prone to electrochemical reaction and corrosion when contacting with some metals. Therefore, contact with other metals should be avoided, especially in humid environment.Keep away from kindling and heat sources.The storage temperature shall not exceed 35 ℃, the container shall be kept sealed, and it is strictly prohibited to contact with the air.It shall be stored separately from oxidants, acids, halogens, etc., and mixed storage is strictly prohibited.Equip with corresponding types and quantities of fire-fighting equipment.The storage area shall be equipped with appropriate materials to contain leakage.Periodically inspect the stored titanium metal to ensure that its appearance has no obvious change or corrosion signs.If any problem is found, measures shall be taken in time.[8]
Closed operation, local exhaust.Operators must be specially trained and strictly abide by the operating procedures.It is recommended that operators wear self-priming filter type dust masks, safety goggles, gas penetration suits and anti poison penetration gloves.Keep away from kindling and heat sources, and smoking is strictly prohibited in the workplace.Use explosion-proof ventilation systems and equipment.[7]Avoid dust generation.Avoid contact with oxidants, acids and halogens.Handle in argon.Load and unload gently during transportation to prevent damage to packaging and containers.Fire fighting equipment and leakage emergency treatment equipment of corresponding types and quantities shall be provided.Empty containers may leave harmful substances.[8]
For the sake of safety, the storage shall always be wetted and passivated with not less than 25% water.Store in a cool and ventilated warehouse.Keep away from kindling and heat sources.The storage temperature shall not exceed 30 ℃, and the relative humidity shall not exceed 80%.Keep the container sealed and do not contact with air.It shall be stored separately from oxidants, acids, halogens, etc., and mixed storage is strictly prohibited.Equip with corresponding types and quantities of fire-fighting equipment.The storage area shall be equipped with appropriate materials to contain leakage.[8]
Transport method
The transport vehicles shall be equipped with corresponding types and quantities of fire-fighting equipment and leakage emergency treatment equipment.The exhaust pipe of the vehicle transporting the product must be equipped with fire arresting device.During transportation, the container shall not leak, collapse, fall or be damaged.It is strictly prohibited to mix with oxidants, acids, halogens, edible chemicals, etc.During transportation, it shall be protected from sun exposure, rain and high temperature.Keep away from kindling and heat sources during stopover.Thoroughly clean the vehicle after transportation.It is forbidden to slip during railway transportation.[8]
