English
Tungsten is part of rare and refractory metals, is also an important strategic metal tungsten mine in
ancient times was known as the "millstones."
Tungsten is the highest melting point (about 3400 ℃) of pure metals at room temperature in any
concentration of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, aqua regia and alkali are
stable. But tungsten is brittle at room temperature, cold state to processing difficulties; the same time,
easily oxidized when heated to a high temperature in the air, limiting its application to expand. Join
tungsten alloy can be significantly improved strength, ductility and resistance to oxidation. At 1900 ℃
when tungsten alloy strength up to 440MPa, while others are already molten metal, so a tungsten alloy
can be used as high-temperature structural materials, such as jet engine nozzle manufacture, import
and export engine casing and spacecraft thrusters.
High-speed tool steel is the addition of more high-carbon tungsten alloy steel (such as W18Cr4V),
heat resistance, wear resistance and toughness is much superior than tool steel, widely used to make
high-speed cutting tools such as turning, twist drilling, milling and so on.
Commonly used cemented carbide contains more high hardness, high melting point, high wear-resistant
tungsten carbide, at about 1000 ℃ still maintain high hardness and wear resistance, high-speed steel is
more resistant than the more heat, which tool cutting speed can be increased to 200m / s or so.
Tungsten copper alloy and tungsten alloy powder metallurgy Preparation of silver, and copper and
silver both high conductivity and wear resistance of tungsten, manufacturing Knife switches, circuit breakers,
spot welding electrodes such as the ideal contact material.
Tungsten wire, ribbon and compact tungsten metal parts are widely used in electrical lighting and
electronics industries. Tungsten filament incandescent lamp is an ideal material because of its high operating
temperatures, high luminous efficiency, low evaporation rate, long life. Also as tungsten hot cathode tube and
a gate, and a variety of high-voltage rectifier cathode instrument indirectly heated cathode heater; tungsten can
be used as x-ray tube target, gas discharge tubes, all kinds of electrical contacts and TIG welding electrodes, also
used as a high-temperature furnace heating element, the working temperature of more than 3000 ℃.
Currently mined in the world tungsten ore, about 50% for high-quality steel smelting, about 35%
for the production of rigid steel, about 10% for the system tungsten wire, about 5% of other used for
other purposes. Tungsten can be manufactured guns, rocket propulsion nozzles, cutting metal blade,
drill, hard mold, drawing dies and so on, uses a wide range of tungsten, involving mining, metallurgy,
machinery, construction, transportation, electronics, chemicals, light industry , textile, military, aerospace,
science and technology, in various industrial fields.
