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Physical properties of tantalum

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Physical properties of tantalum

Chemical symbol TA, steel gray metal, belongs to VB group in the periodic table of elements, atomic number 73, atomic weight 180.9479, body centered cubic crystal, common valence is +5. The hardness of tantalum is low and related to oxygen content. The Vickers hardness of ordinary pure tantalum in annealed state is only 140hv [1]. Its melting point is as high as 2995 ℃ [1], ranking fifth only to carbon, tungsten, rhenium and osmium. Tantalum is malleable and can be drawn into thin foil. Its coefficient of thermal expansion is very small. For every one degree Celsius rise, it will only expand by 6.6 parts per million. In addition, its toughness is very strong, even better than copper.

CAS No.: 7440-25-7

Element category: transition metal elements.

Relative atomic mass: 180.94788 (12c = 12.0000)

Density: 16650 kg/m ³; 16.654 g/cm ³

Hardness: 6.5

Location: sixth cycle, VB family, Zone D

Appearance: steel gray metal

Electronic layout: [xe] 4f14 5d3 6s2

Atomic volume: 10.90 cm3/mol

Content of elements in seawater: 0.000002ppm

Content in crust: 1 ppm

Oxidation state: +5 (main), -3, -1, 0, +1, +2, +3

Crystal structure: the cell is body centered cubic cell, and each cell contains 2 metal atoms.

Cell parameters:

a = 330.13 pm

b = 330.13 pm

c = 330.13 pm

α  = 90°

β  = 90°

γ  = 90°

Vickers hardness (arc melting and cold work hardening): 230hv [1]tantalum wire for sale - TIRONG TECH

Vickers hardness (recrystallization annealing): 140hv [1]

Vickers hardness (after one-time electron beam melting): 70hv [1]

Vickers hardness (after secondary electron beam melting): 45-55hv [1]

Melting point: 2995 ℃ [1]

The propagation rate of sound in it: 3400m/s

Ionization energy (kJ /mol)

M - M+ 761

M+ - M2+ 1500

M2+ - M3+ 2100  

M3+ - M4+ 3200

M4+ - M5+ 4300

Discoverer: discovered by Swedish chemist Anders gustafa Ekberg in 1802.

Element naming: Ekberg named the element after Tantalus, the father of Niobe, the queen of the city of central Thebes in ancient Greek mythology.

Source: it mainly exists in tantalite and coexists with niobium.

Chemical properties of tantalum

Tantalum also has excellent chemical properties and high corrosion resistance. It does not react with hydrochloric acid, concentrated nitric acid and aqua regia under cold and hot conditions. However, tantalum can be corroded in hot concentrated sulfuric acid. Below 150 ℃, tantalum will not be corroded by concentrated sulfuric acid. It will react only when the temperature is higher than this temperature. In concentrated sulfuric acid at 175 ℃ for 1 year, the corroded thickness is 0.0004 mm. When tantalum is immersed in sulfuric acid at 200 ℃ for 1 year, the surface damage is only 0.006 mm. At 250 ℃, the corrosion rate increases, with the thickness of 0.116 mm corroded every year. At 300 ℃, the corrosion rate is faster. After soaking for 1 year, the surface is corroded by 1.368 mm. The corrosion rate in fuming sulfuric acid (containing 15% SO3) is more serious than that in concentrated sulfuric acid. After soaking in the solution at 130 ℃ for 1 year, the thickness of the surface corroded is 15.6 mm. Tantalum will also be corroded by phosphoric acid at high temperature, but this reaction generally takes place at above 150 ℃. After soaking in 85% phosphoric acid at 250 ℃ for 1 year, the surface will be corroded for 20mm. In addition, tantalum can be quickly dissolved in the mixed acid of hydrofluoric acid and nitric acid, and can also be dissolved in hydrofluoric acid. But tantalum is more afraid of strong alkali. Tantalum will be dissolved rapidly in a 40% concentration of caustic soda solution at 110 ℃. In a potassium hydroxide solution of the same concentration, it will be dissolved rapidly at 100 ℃. In addition to the above conditions, General inorganic salts generally cannot corrode tantalum below 150 ℃. Experiments show that tantalum has no effect on alkali solution, chlorine, bromine water, dilute sulfuric acid and many other reagents at room temperature, but only reacts under the action of hydrofluoric acid and hot concentrated sulfuric acid. Such a situation is relatively rare in metals.

However, at high temperature, the oxide film on the surface of tantalum is destroyed, so it can react with a variety of substances. At room temperature, tantalum can react with fluorine. At 150 ℃, tantalum is inert to chlorine, bromine and iodine. At 250 ℃, tantalum still has corrosion resistance to dry chlorine. When heated to 400 ℃ in chlorine containing water vapor, it can still remain bright. At 500 ℃, it begins to be corroded. At 300 ℃, tantalum reacts with bromine, and is inert to iodine vapor when the temperature reaches red heat. Hydrogen chloride reacts with tantalum at 410 ℃ to produce pentachloride, while hydrogen bromide reacts with tantalum at 375 ℃. When heated to 200 ℃ or lower, sulfur can interact with TA, and carbon and hydrocarbons can interact with tantalum at 800-1100 ℃.

λ: wavelength

f: Oscillator strength

W: Monochromator spectral passband

N-a (nitrous oxide acetylene flame)

S*: characteristic concentration of elements (1% absorption sensitivity)

CL: detection limit of element

R · s: relative sensitivity between main absorption lines of the same element

F: Flame type

The linear expansion coefficient of tantalum is 6.5 between 0 ~ 100 ℃ × 10-6 k-1, the superconducting transition critical temperature is 4.38k, and the thermal neutron absorption cross section of the atom is 21.3 target.

Tantalum is one of the most chemically stable metals at temperatures below 150 ℃. Only fluorine, hydrofluoric acid, acidic solution containing fluorine ions and sulfur trioxide can react with tantalum. It reacts with concentrated alkali solution at room temperature and dissolves in molten alkali. Dense tantalum begins to oxidize slightly at 200 ℃ and obviously at 280 ℃. Tantalum has a variety of oxides, the most stable of which is tantalum pentoxide (Ta2O5). Tantalum and hydrogen form brittle solid solutions and metal hydrides such as ta2h, TAH, tah2, and tah3 at temperatures above 250 ℃. Under the vacuum of 800 ~ 1200 ℃, hydrogen separates from tantalum, and tantalum recovers plasticity. Tantalum and nitrogen begin to react at about 300 ℃ to form solid solutions and nitrogen compounds; At higher than 2000 ℃ and high vacuum, the absorbed nitrogen separates out from tantalum. Tantalum and carbon exist in three phases above 2800 ℃: carbon tantalum solid solution, low valence carbide and high valence carbide. Tantalum can react with fluorine at room temperature and with other halogens above 250 ℃ to form halides.

Tantalum forms a stable anodic oxide film in the acid electrolyte. Electrolytic capacitors made of tantalum have the advantages of large capacity, small volume and good reliability. Capacitor making is the most important use of tantalum, and the consumption in the late 1970s accounted for more than 2/3 of the total consumption of tantalum. Tantalum is also the material for making electronic emission tubes and high-power electronic tube parts. The corrosion-resistant equipment made of tantalum is used in the production of strong acids, bromine, ammonia and other chemical industries. Tantalum can be used as the structural material of the combustion chamber of aircraft engine. Tantalum tungsten, tantalum tungsten hafnium and tantalum hafnium alloys are used as heat-resistant and high-strength materials for rockets, missiles and jet engines, as well as parts of control and adjustment equipment. Tantalum is easy to process and form, and can be used as supporting accessories, heat shields, heaters and heat sinks in high-temperature vacuum furnaces. Tantalum can be used as orthopedic and surgical materials. For example, tantalum bars can be used to replace bones and muscles in the human body, and also grow on tantalum bars, so it has a "biophilic metal". Tantalum carbide is used in the manufacture of cemented carbide. Tantalum borides, silicides, nitrides and their alloys are used as heat release elements and liquid metal cladding materials in the atomic energy industry. Tantalum oxide is used in the manufacture of advanced optical glasses and catalysts. In 1981, the consumption proportion of tantalum in various departments in the United States was about 73% in electronic components, 19% in machinery industry, 6% in transportation and 2% in others.

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