What is Tungsten?

Tungsten (pronounced /t??st?n/), also known as wolfram (/wlfr?m/), is a chemical element with the chemical symbol W and atomic number 74. Tungsten is as known the heaviest materials except gold of the nature resources, for the density of tungsten is 19.25 ?g?cm?3(near r.t.). For the same reason, tungsten related products, alloys(Nickel-Copper-Ferro Binder), other elements doped(Al-doped, Th-doped, La-dope, Ce-dopd and K-doped) and carbides( carbonized tungsten powder with cobalt or Nickel binder) have the special ccharacteristics as pure tungsten, then it always named heavy stone.

Tungsten is a typiacl element of transition element Group VI and shows oxidation states from +6 to-2 and, particularly in its oxides, forms many non-stoicheiometric compounds. There is little aqueous chemistry except that of complex oxy-anions and some complex halides. The hexahalides are moleular but lower halides are polymeric and the lowest halides show extensive W-W bonding (more than Mo). Carbonyl and phos-phine derivatives are typical low oxidation state compounds. Complexes are formed, particularly by O-and S-ligands in higher oxidation states and by P-ligands in low oxidation states. Complex cyanides are well established.

Tungsten is one of Nonferrous Metals, and also it is as molybdenum and rare earth which are Refractory Metals, in the modern industrial time, it is the most important Strategic Metals for IT industrial and military industrial.

What is the problem with tungsten? Tungsten dissolves readily in water and is mobile under some field conditions, challenging initial assumptions with regard to tungsten’s fate and transport characteristics. Other concerns include data (occupational, animal studies, cancer clusters) indicating adverse non-cancer and cancer health effects and risk outcomes.

How is tungsten used? Tungsten alloys are good conductors of electricity, and used primarily to increase the toughness and strength of steel. The most common tungsten product, cemented tungsten carbide, is used to make grinding wheels and cutting or forming tools. Tungsten powder is used as a lead replacement in bullets. However, firing of a tungsten/nylon bullet introduces tungsten and other projectile related metals into the environment.

How does exposure to tungsten affect human health?

The toxicology of tungsten depends on the route of administration, the solubility of the constituent and the duration of exposure. Occupational exposure via the inhalation pathway has revealed elevated levels of pulmonary fibrosis (scarring of the lung tissue) and other effects including asthma and inflammation of the nose tissues.  Research also suggests that the combination of tungsten and other substances can be linked to the development of lung cancer.  Some animal data suggests that tungsten could cause adverse developmental and reproductive effects (including the kidneys as a target organ). Information from Nevada has drawn attention to tungsten’s potential toxicity as exhibited in the Fallon Nevada cancer cluster.

主站蜘蛛池模板: 亚洲VA综合VA国产产VA中| 丁香婷婷综合网| 91在线亚洲综合在线| 亚洲狠狠婷婷综合久久蜜芽| 久久99国产综合精品女同| 伊人色综合久久天天网| 综合久久给合久久狠狠狠97色| 色综合婷婷在线| 欧美综合自拍亚洲综合图| 狠色狠色狠狠色综合久久| 天天影视综合色区| 少妇熟女久久综合网色欲| 久久久久青草线蕉综合超碰| 狠狠88综合久久久久综合网| 色综合久久久久无码专区| 激情五月综合网| 狠狠色综合网站久久久久久久高清 | 色综合久久中文色婷婷| 97se色综合一区二区二区| 婷婷五月综合色视频| 亚洲乱码中文字幕综合234 | 国产成人99久久亚洲综合精品| 欧美一区二区三区久久综合| 国产亚洲精品精品国产亚洲综合 | 久久一本综合| 欧美αv日韩αv另类综合| 色欲色香天天天综合网站| 欧美综合自拍亚洲综合图| 激情综合网五月| 欧美久久综合九色综合| 欧美综合视频在线| 亚洲 欧美 国产 动漫 综合| 色综合色综合色综合| 一个色综合久久| 日韩亚洲欧美久久久www综合网| 亚洲狠狠婷婷综合久久久久| 欧美综合自拍亚洲综合图片区| 六月婷婷国产精品综合| 三级韩国一区久久二区综合| 国产成人精品综合久久久久 | 美国十次狠狠色综合|