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Tungsten

1 week ago   Freebies   Cambridge   22 views Reference: 22929

0.0 star

Location: Cambridge


Tungsten, meaning “heavy stone” in Swedish, is a very hard and heavy silver gray rare metal. With the highest melting point among metals, tungsten has a relatively large electric resistance as a metal, so it is used for heaters and reflectors in furnaces exceeding 2000.

Furthermore, lead solder is cheaper and easier to use than lead-free solder. The main reason why manufacturers are shifting to the use of lead-free solder is to eradicate lead from electronic production and waste recycling processes. In the past two decades, the electronic manufacturing world has experienced a dynamic development of alternative soldering materials centered on tin metal.

Because pure tungsten is expensive and difficult to manufacture and machine, alternative materials were sought which would maintain some of the useful characteristics of tungsten, such as density and X-ray shielding capabilities, but which would be easier to machine and less expensive. The result of this quest are the Heavy Tungsten Alloys. Tungsten heavy alloys are ideal for high-density applications or for use in radiation shielding. Heavy metal tungsten alloys are 90% to 97% pure tungsten in a matrix of nickel/copper or nickel/iron. Heavy metal alloys are pseudo alloys of tungsten with a nickel iron or nickelcopper matrix. They are produced by powder metal and sintering processes. Tungsten Heavy Alloys has a high density of 1719 g/cm³. Comparable densities are only reached by gold or platinum. These alloys are used as mass balancing weights and attenuators in aircraft construction, in motors and power trains, as oscillating weights and centrifugal weights in machines and in equipment construction, and in medical technology for both protection from and focusing of ionizing radiation in x-ray and measuring devices.

Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements barring carbon (which sublimes at normal pressure), melting at 3,410 °C (6,170 °F; 3,683 K). It also has the highest boiling point, at 5,930 °C (10,706 °F; 6,203 K). Its density is 19.30 grams per cubic centimetre, comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw.

There is one kind of tungsten silicone-based shielding product, that made with tungsten, iron, bismuth or mixtures of these metals. The advantages of tungsten silicone-based shielding are base on the good performance of tungsten, iron, and bismuth. Tungsten silicone-based material offers the ability to put the shielding as close as possible to the source. In situations where space is limited, tungsten allows for the highest attenuation with the lowest shielding thickness and excellent radiation absorption. Iron provides a much less expensive option when space is not as limited. Bismuth is the middle ground offering excellent attenuation at a wide range of gamma energies. Tungsten silicone-based shielding can be formed into almost any size or shape. Tungsten carbide mechanical seals had been the preferred thing for several years. However, in recent times, they have been replaced by a strong competitor, silicon carbide seal faces. What could be the secret of this change of preference? Well, it is because of some prominent benefits.It does not mean that tungsten carbide seal faces have become obsolete. There are many applications where only Tungsten seal faces can work. This blog, not just rates rate a particular type of seal face higher to the other, but it gives a comprehensive analysis of the two. Thus, a user may pick the most suitable seals for the application. What is the primary reason for installing a seal? It is to keep the pollutants away and increase their life. The seal has two parts- one stationary and one rotating. The rotating or stationary part is made from either of the two materials that is used in the seal.


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