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: 久久综合亚洲色一区二区三区| 亚洲精品综合一二三区在线| 亚洲国产成人久久综合碰| 综合国产在线观看无码| 99久久伊人精品综合观看| 亚洲精品欧美综合| 亚洲VA综合VA国产产VA中| 亚洲欧美成人综合在线| 亚洲综合日韩精品欧美综合区| 激情综合色五月六月婷婷| 一本一道久久a久久精品综合| 久久综合亚洲色HEZYO社区| 欧美色综合天天综合高清网| 狠狠色综合日日| 国产激情电影综合在线看| 国产成人综合美国十次| 久久综合色之久久综合| 精品亚洲综合在线第一区| 欧美精品国产日韩综合在线| 丁香五月婷婷综合激情在线| 激情97综合亚洲色婷婷五| 91精品婷婷国产综合久久| 亚洲综合精品一二三区在线| 亚洲综合一区二区精品导航| 日韩欧美色综合网站| 一本色综合久久| 亚洲色欧美色国产综合色| 色综合久久久久网| 亚洲成色在线综合网站| 色五月丁香六月欧美综合| 91精品一区二区综合在线| 狠狠色丁香久久婷婷综合图片| 亚洲综合亚洲综合网成人| 欧美色综合久久久久久| 亚洲综合第一页| 亚洲中文字幕无码久久综合网| 一本久道久久综合狠狠躁AV| 久久狠狠爱亚洲综合影院| 91精品国产91久久综合| 天天干天天射综合网| 久久久久久综合网天天|