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Tungsten Widely Used
May 25, 2017

Tungsten and its alloys are widely used in electronic and electric light industry. Used for the manufacture of various lighting bulbs, Tungsten the electronic tube filament is a doped tungsten filament with anti SAG properties. Adding rhenium in doped tungsten wire. A thermocouple made from tungsten-rhenium alloy wires with low rhenium content and tungsten-rhenium alloy wires with high rhenium content, its temperature range is very wide (2500), Tungsten the linear relationship between thermal and thermal dynamic potential is good, the reaction speed is fast (3 seconds), the price is relatively cheap, it is the ideal thermocouple in the hydrogen atmosphere.

Tungsten wire Not only triggered a revolution in the lighting industry, Tungsten but also because of its high melting point, without losing its mechanical integrity of the premise of becoming a kind of electron thermal ion emitter, such as scanning electron microscope and transmission electron (microscopic) mirror electron source. Also used as a filament for X-ray tubes. In the X-ray tube, the electrons produced by the tungsten wire are accelerated to impact tungsten and tungsten-rhenium alloy anodes, and X-rays are emitted from the anode. Tungsten In order to produce X-rays, the energy of the electron beam produced by the tungsten filament is very high, so the spot on the surface of the electron beam collision is very hot, so the rotating anode is used in most X-ray tubes. In addition, large sized tungsten wires are also used as heating elements of vacuum furnaces. Tungsten has a density of 19.25 g/cm 3, about 2.5 times times the iron (7.87 g/cm 3), and is one of the heaviest metal elements in the periodic system. Tungsten The high density tungsten alloy, which is based on tungsten, has become an important application field in tungsten. The high density tungsten alloy can be made by adding nickel, iron, copper and a few other elements in the tungsten powder by liquid phase sintering process. According to the different components, high density tungsten alloy can be divided into tungsten-nickel-iron and tungsten-nickel-copper two alloy systems. Through the liquid phase sintering, the density can reach 17 18 gram/cm 3. The so-called liquid phase sintering is the sintering process where the mixed powder compacts have a certain amount of liquid in the sintering temperature. The advantages are that liquid phase wetting solid particles and dissolving a small amount of solid matter, Tungsten greatly accelerate the densification and grain growth process, and achieve extremely high relative density. For example, for the nickel-iron powder commonly used in liquid phase sintering, when sintering occurs, the nickel-iron powder melts. Although the solubility of liquid nickel iron in solid tungsten (95% of the body fraction) is very small, solid tungsten is easily dissolved in liquid nickel iron. Once the liquid nickel iron wetting the tungsten particles and dissolve a part of the tungsten powder, the tungsten particles change the shape of the internal pores when the liquid flow into the Tungsten immediately disappear. The process continues, the tungsten particles continue to coarsening and grow, and eventually produce close to 100% compact and have the best microstructure of the final product.

The high density tungsten alloy with liquid phase sintering has better impact performance than pure tungsten, and its main purpose is to manufacture highly penetrating military armor piercing.

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