https://zh.wikipedia.org/wiki/%E9%92%A8
https://en.wikipedia.org/wiki/Tungsten
tungsten is found naturally on Earth almost exclusively in chemical compounds.
Polycrystalline tungsten is an intrinsically brittle[6][7] and hard material, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw.[8]
Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. Tungsten's hardness and high density give it military applications in penetrating projectiles.
Because it retains its strength at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications,[62] such as light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles.[8] Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process (also called tungsten inert gas (TIG) welding).
纯钨是钢灰色至锡白色的坚硬金属 。
在所有金属中钨的熔点最高(3415℃)蒸汽压最低 。钨的防腐性能非常好，
大多数无机酸对其的侵蚀都很小。
在空气裡它的表面會形成一层保护性氧化物，但是在高温下会完全氧化。
在钢裡加入少量钨可以大為增高钢的硬度。
https://en.wikipedia.org/wiki/Tungsten
tungsten is found naturally on Earth almost exclusively in chemical compounds.
Polycrystalline tungsten is an intrinsically brittle[6][7] and hard material, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw.[8]
Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. Tungsten's hardness and high density give it military applications in penetrating projectiles.
Because it retains its strength at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications,[62] such as light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles.[8] Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process (also called tungsten inert gas (TIG) welding).
黑钨矿、白钨矿、钨铁矿等矿物含钨。
中国出产全世界钨的75%。
通过使用碳还原钨的氧化物获得纯的金属。
全世界钨的贮藏总量估计为700万吨，其中约30%是黑钨矿，70%是白钨矿。但是目前大多数这些矿藏无法经济性地开采。按照目前的消耗量这些矿藏只够使用约140年。
另一个获得钨的方法是回收。回收的钨比钨矿含量高，事实上非常有利润。
纯钨是钢灰色至锡白色的坚硬金属 。
在所有金属中钨的熔点最高(3415℃)蒸汽压最低 。钨的防腐性能非常好，
大多数无机酸对其的侵蚀都很小。
在空气裡它的表面會形成一层保护性氧化物，但是在高温下会完全氧化。
在钢裡加入少量钨可以大為增高钢的硬度。
