Tungsten can only be used for light bulbs? Wrong! It is an important part of modern high-tech new materials!
Tungsten is the refractory metal with the highest melting point. Generally, metals with a melting point higher than 1650℃ and certain reserves and metals with a melting point higher than zirconium (1852℃) are called refractory metals.
Tungsten is a rare metal with high melting point, which can improve the high temperature hardness of steel. It belongs to ⅥB group of the sixth period (the second longest period) in the periodic table of elements. Tungsten is a silvery white metal that looks like steel. Tungsten has a high melting point, a low vapor pressure and a low evaporation rate. Tungsten has very stable chemical properties. It does not react with air and water at room temperature. When it is not heated, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid and aqua aqua at any concentration have no effect on tungsten.
Tungsten dissolves rapidly in a mixture of hydrofluoric acid and concentrated nitric acid at room temperature, but does not work in alkaline solutions. In the presence of air, the molten base can oxidize tungsten to tungstate, and in the presence of oxidants (NaNO3, NaNO2, KClO3, PbO2), the reaction to form tungstate is more violent. It can be combined with oxygen, fluorine, chlorine, bromine, iodine, carbon, nitrogen, sulfur at high temperature, but not with hydrogenation.
Important use of tungsten
Tungsten is widely used in modern technology in the form of pure metal and alloy system. In the alloy system state, the most important ones are alloy steel, tungsten carbide based hard alloy, wear-resisting alloy and strong heat alloy.
Tungsten is mainly used in the following industrial fields:
The carbide of tungsten has high hardness, wear resistance and refractory. These alloys contain 85 to 95 percent tungsten carbide and 5 to 14 percent cobalt, a metal that acts as a binder and gives the alloy the necessary strength.
As the most difficult metal to melt, tungsten is a component of many thermal-strength alloys, such as alloys composed of 3% -- 15% tungsten, 25% -- 35% chromium, 45% -- 65% cobalt, and 0.5% -- 0.75% carbon. It is mainly used for strong wear-resistant parts. For example, the valve of the aero engine, the working parts of the die cutting tool, the turbine impeller, the excavation equipment, the surface coating of the plow head.
Alloys of tungsten and other refractory metals (e.g., tantalum, niobium, molybdenum, rhenium) are used as thermally strong materials in aerospace rocketry and in other sectors where high thermal strength is required of machine parts, engines, and some instruments.
It is these properties that make tungsten an important material for nuclear fusion, especially the retention of hydrogen and its isotopes in tungsten.
Important strategic metal
Tungsten is a rare metal. Rare metals usually refer to the metals which are found in small amount or scattered in nature. Tungsten is a widely distributed element, occurring in almost all types of rocks, but in relatively low concentrations. The content of tungsten in the crust is 0.001% and in granite is 1.5×10-6 on average.
This characteristic makes it very difficult to extract, usually can only be separated by organic solvent extraction method and ion exchange method. With the progress of science and technology, the development of metallurgical technology, equipment, analysis and testing technology and the expansion of the production scale of rare metals, the purity, performance and variety of tungsten have been continuously improved, and the application field of tungsten has been expanded. China is rich in tungsten mineral resources, the output and export of tungsten are the first in the world.
Tungsten is a strategic metal. As is known to all, rare metals are important strategic resources of the country, and tungsten is a typical rare metal, which has extremely important uses.
It is an important part of modern high-tech new materials, a series of electronic optical materials, special alloys, new functional materials and organometallic compounds all need to use unique properties of tungsten. The amount of it is small, but it is vital. It is indispensable. Therefore, it is widely used in contemporary communication technology, electronic computer, aerospace development, medicine and health, photosensitive materials, photoelectric materials, energy materials and catalyst materials, etc.
