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Tungsten ( W )

Material Information

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Bolt Foil Insulated Wire Lump Mesh Microfoil Nut Powder Rod
Bolt Foil Insulated Wire Lump Mesh Microfoil Nut Powder Rod
Sheet Single Crystal Sputtering Target Tube Washer Wire
Sheet Single Crystal Sputtering Target Tube Washer Wire

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General Description:  

Tungsten was isolated in 1783 by J.J. and F. Ehuijar in Vergara, Sweden.

Tungsten metal is lustrous and silvery white in color, and does not occur naturally (it has an abundance of 1 ppm in the earth's crust). It is found in the ore Wolframite, a tungstate of iron and manganese, (FeMn)WO4, which is converted to the trioxide and then reduced to the metal by reduction in hydrogen (carbon cannot be used as the very stable carbide would result). Tungsten metal is relatively inert, resisting attack by oxygen, acids and alkalis, although it will react with fused, oxidising alkali media. It has the highest melting point of all metals and, when pure, it can be worked with relative ease; however, the presence of impurities renders tungsten extremely brittle and, therefore, difficult to fabricate.

The high melting point of tungsten makes it suitable for use as electric filaments (e.g. in electric light bulbs). It is also the basis of a range of alloys containing tungsten, copper and nickel which are used for radiation shielding as they provide a 50% increase in density compared to lead. Tungsten and its alloys also find uses in military applications (e.g. armour and shells), as well as counter-balance materials. Tungsten carbide powder (with possible additions of titanium and tantalum carbides) along with nickel or cobalt powders, are compressed and sintered to produce cemented carbides. These products are used in place of high speed steel to form the tip of cutting and drilling tools, or for parts which will be subjected to heavy useage.

   

Atomic Properties

Atomic number 74
Atomic radius - Goldschmidt ( nm ) 0.141
Atomic weight ( amu ) 183.85
Crystal structure Body centred cubic
Electronic structure Xe 4f14 5d4 6s2
Ionization potential No. eV
1 7.98
2 17.7
Natural isotope distribution Mass No. %
180 0.1
182 26.3
183 14.3
184 30.7
186 28.6
Photo-electric work function ( eV ) 4.55
Thermal neutron absorption cross-section ( Barns ) 18.5
Valences shown 2, 3, 4, 5, 6

Electrical Properties

Electrical resistivity @20C ( µOhmcm ) 5.4
Temperature coefficient @0-100C ( K-1 ) 0.0048
Superconductivity critical temperature ( K ) 0.0154
Thermal emf against Pt (cold 0C - hot 100C) ( mV ) +1.12

Mechanical Properties

Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa )     311
Hardness - Vickers 360 500
Poisson's ratio     0.28
Tensile modulus ( GPa )     411
Tensile strength ( MPa ) 550-620 1920
Yield strength ( MPa ) 550

Physical Properties

Boiling point ( C ) 5660
Density @20C ( g cm-3 ) 19.3
Melting point ( C ) 3410

Thermal Properties

Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 4.5
Latent heat of evaporation ( J g-1 ) 4009
Latent heat of fusion ( J g-1 ) 192
Specific heat @25C ( J K-1 kg-1 ) 133
Thermal conductivity @0-100C ( W m-1 K-1 ) 173

Buy Tungsten on-line

We stock and supply the following standard forms:
Bolt Foil Insulated Wire Lump Mesh Microfoil Nut Powder Rod
Bolt Foil Insulated Wire Lump Mesh Microfoil Nut Powder Rod
Sheet Single Crystal Sputtering Target Tube Washer Wire
Sheet Single Crystal Sputtering Target Tube Washer Wire

Choose a form to search our on-line catalog  

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