Tungsten and oxygen(5)

Tungsten and oxygen

PP: D: 7.21-7.30 g·cm^-3 (measured), 7.27 g·cm^-3 (X-ray); MP: 1472℃; significant sublimation starts already far below the melting point at >750℃. The presence of water vapor enhances the volatility considerably; BP: 1837℃ (at this temperature the sum of the volatile partial pressures corresponds to 1 bar). The volatile species are only polymeric molecules (in mol%: 23.7 W2O6, 0.57 W3O8, 58.2 W3O9, 17.53 W4O11); MH: 83-163 kg·mm^-2 (50g); CO: yellow (smallest diminution of oxygen changes the color to different types of green); at lower temperature (-27 to -50℃) it is bluish white and at <-50℃ white. At elevated temperature the color changes to brownish yellow; 

electrical resisdvity:0.14-0.18Ω·cm; HR:

 

titanium rings are lighter than tungsten rings but durable

Tungsten and oxygen(4)

Tungsten and oxygen

1.Stoichiometric Binary Oxides

Tungsten Trioxide:

 

PR: By calcination of tungstic acid or APT in air or oxygen:

By oxidation of tungsten powder (for stoichiometric WO3 the oxygen partial pressure has to be higher than in air).

beautiful tungsten pendant

Tungsten and oxygen(3)

Tungsten and oxygen

By the loss of each oxygen atom from the oxide lattice two electrons are added to the conduction band. Reduced compounds are therefore either semiconducting or conducting.

Besides the tungsten-oxygen octahedra, WO4 tetrahedra can also be found in fully oxidized compounds (tungstates), as well as WO7 pentagonal bipyramids in reduced compounds.

Several hundreds or even thousands of ternary and quaternary tungsten oxides are known today. They are only partly described in the literature and can be found in the relevant compilations. They are, however, the top of an iceberg of a much larger number of compounds which might form, in principle, with a large number of elements and/or element combinations. In this sense, the crystal chemistry of tungsten oxides can be regarded as one of the most complex and richest fields in the structural chemistry of the elements.

tungsten necklace, fashion jewelry

Tungsten and oxygen(2)

Tungsten and oxygen

In the fully oxidized state (W6+) the octahedral coordination dominates (WO6). The tungsten atoms are situated in the center of octahedrons and are surrounded by six oxygen atoms arranged at the corners. As long as all tungsten ions are hexavalent, these octahedrons are only corner-sharing.

WO6 octahedron; (a) Locations of the centers of the atoms; the black circle is tungsten, the white circles oxygen. (b) Atoms shown in full size; the tungsten atom is the small circle.

However, as the oxygen-to-tungsten ratio decreases, which occurs on reduction (transition to lower oxides), the octahedra become more and more intricately joined in combinations of corner-, edge-, and face-sharing.

Tungsten and oxygen

Tungsten and oxygen

The tungsten-oxygen system is rather complex. Besides the stable stoichiometric binary oxides (WO 3, WO 2.9, WO 2.72, and WO 2), and the stoichiometric tungstates and acids, a variety of nonstoichiometric, fully oxidized and reduced compounds exists, according to the scheme in Figure below.

 

Survey of tungsten-oxygen compounds

Tungsten and humans(4)

Tungsten and humans

This parenchymal disease (fibrosing alveolitis) was only observed to occur among hardmetal (cemented carbide) and diamond workers, the clinical presentation of which may vary from subacute alveolitis to progressive fibrosis. Although at first WC was thought to be responsible, and later Co, now it is evident that only the presence of both hardmetal components induces hardmetal disease, characterized in the early stages by the presence of bizarre, multinucleated giant cells in the lung interstitium, alveolar lumen, and the broncho alveolar lavage. In contrast, parenchymal toxicity could never be observed when exposure was to Co alone WC alone or WC alone. Moreover, an increased risk of lung cancer was found in hardmetal workers.

Tungsten chain is tough, scratch resistant and durable, due to the characteristics of tungsten

Tungsten and humans(3)

Tungsten and humans

Hardmetal Disease
The association between parenchymal lung disease and hardmetal exposure was first observed in Germany and several later reports exist from other countries. An extensive summary of the related literature in regard to clinical surveys, epidemiological studies, clinical presentation, pathology, and hypotheses on pathogenesis was presented recently by D. Lison and co-workers [14.6,14.7].

Tungsten earring can maintain its shape and glossy for a long time

Tungsten and humans(2)

Tungsten and humans

Important data

Average Tungsten Level in Blood is 5.8±3.5μg W·1^-1 (1μg W·1^-1).

Average Tungsten Level in Bones is 0.25ppb W.

Demand per Day is 1-15μg.

Occupational Health. MAX/NIOSH (TLV-TWA):1mg·m^-3 W or souble W compounds, 5 mg·m^-3 WC or other insoluble compounds.

Patch Test. In 853 tested workers, 2% showed irritant pustular reactions when exposed to Na2WO4.

Due to the special nature of the tungsten alloy, now, it is increasingly being used in rings instead of Gold & Platinum

Tungsten and humans

Tungsten and humans

In comparison to the majority of other heavy metals, tungsten and most of its compounds possess very low toxicity, if at all. Intoxications occur rarely, almost exclusively by occupational exposure. As treatment in acute poisoning, Dimercaprol (British Antilewisite) may be useful.

Watch band and case made of tungsten alloy are more wear resistant and scratch resistant

Sapphire and tungsten

Sapphire and tungsten

Because of its dielectric and crystallographic properties, sapphire is the wafer material for producing a variety of electronic applications. And sapphire is the basic material for LED production.

LED sapphire products

The melting point of tungsten is 3410 ℃ and the boiling point is 5900 ℃. At 10~100℃, the thermal conductivity of tungsten is 174 W / m·K. The hardness and density of tungsten is high (density is 19.25g/ cm3). Therefore, tungsten is widely used in crucible, heater, cover plate and base plate, heat shield in the sapphire production.

 

 tungsten crucible

 tungsten cover plate

The distribution of tungsten ore in China

The distribution of tungsten ore in China

In China, the tungsten ore is the advantage mineral resources. Now the mining areas has been discovered and proven is about 252 place. And the proved reserves (WO₃, the same below) is 6.375 million tons in total, in which class A and class B and class C reserves of 2.32 million tons, accounting for 36.4%.

picture by chinamining

The world's largest tungsten mine(2)

The world's largest tungsten mine

It is reported, the proved reserves have more than the existing maintain reserves of the sum of tungsten in Jiangxi Province. The project has not only proven to a million tons of tungsten metal associated with a large copper mine, a large silver mine and a medium-sized molybdenum mine. According to the geological team captain, after integrated, the area of mining right is 10.92 square kilometers. The discovery of scheelite, changed the history of the Da Hutang only focus on wolframite in the past. Da Hutang mining area and the peripheral ore prospects are good, and to find another big tungsten ore is entirely possible.

The world's largest tungsten mine

The world's largest tungsten mine

The Ministry of Land and Resources of the People's Republic of China on June 5 p.m. news, Da Hutang, a small place in Wuning County, Jiujiang City, Jiangxi, exploration of a tungsten mine which reserves of 1.06 million tons of tungsten ore after 18 months of exploration. And this is the world's largest tungsten mine.

Nickel Silver Dart

Nickel Silver Dart

The nickel silver barrel with dimple tip compose nickel silver dart. The weight of the dart is available from 20 to 26 grams. The barrels of the darts are made of durable nickel silver combination and color master shafts.

Tungsten and lamp(33)

A family's day with Tungsten

After dinner, father invites the whole family to the cinema to see an exciting thriller. It is always fascinating to see a thriller in wide angle projection with the clarity and brightness only Xenon short arc lamps equipped with Tungsten electrodes can deliver.

 

photo by 420magazine & periodictable

A long day has ended and father is happy when the time comes to relax and, perfectly satisfied, he switches off his beloved little 15W Tungsten lamp with its warm and peaceful light.

Sleeping perfectly after a day with Tungsten.

photo by homedosh

Presentation given at the occasion of the “Celebration of the 100^th Anniversary of Chinese Tungsten Industry” in Ganzhou, Jiangxi, Nov. 2007.

Burghard Zeiler, Wolfram Bergbau- und Hütten-GmbH Nfg. KG

Wolf-Dieter Schubert and Erik Lassner, Institute of Chemical Technologies and Analytics – Vienna University of Technology.

A family’s day with Tungsten is end...

Tungsten and rc racing cars(32)

A family’s day with Tungsten

The son is browsing the internet, because he wants to buy some tuning parts for his remote control racing car.

Tungsten carbide differential balls are used for RC car racing.

A set of Tungsten balls for the differential would be great. As a replacement for the original steel balls they would cause lower friction and much lower wear. Unfortunately they are out of stock. Obviously high demand for Tungsten even in the hobby sector. He tells his father, that also in full scale Formula One racing cars Tungsten parts are used to optimize the setting and achieve the highest performance on the track.

A family's day with Tungsten(31)

A family's day with Tungsten

Mother complained because of the high price, but now she is happy to see her husband relaxing after a hard day’s work, when optimizing the adjustment of the record players tone arm by fine tuning the position of the Tungsten counterweight. This Tungsten part is not only a counterweight, but is also vibration damping and thereby improving the audio quality.

Tungsten counterweight(photo by DIY Audio Projects)

A family's day with Tungsten(30)

A family's day with Tungsten

The father is an audiophile and only recently bought an analogue vinyl record player.

Audiophiles prefer analogue vinyl record players

Parts of heavy metal or tungsten copper are used as counterweight and gearing block of the pick-up.

A family's day with Tungsten(29)

A family's day with Tungsten

Mother is cooking a perfect dinner. To sharpen her knives, she uses a Cemented Carbide sharpening tool.

The daughter is playing the guitar. Father immediately realized the special sound and learned that she is using special strings with Tungsten wire applications.

tungsten electric guitar