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The uses and smelting method of silicon metal

According to metal powder supplier, silicon metal ( also known as industrial silicon ) is a name of commodity appeared in 1960s. Its appear is related to the rise of semiconductor industry. 

At present, the international general put the silicon goods into metal silicon and semiconductor silicon. Silicon metal is made of quartz and coke in the electric heating furnace smelted into products, principal component silicon content is about 98% ( in recent years, also have content 99.99% Si of silicon metal ), the remaining impurities is iron, aluminium, calcium. Semiconductor silicon used in producing semiconductor device of high purity silicon metal. Is sell as polycrystalline, single crystal morphology, the formal is cheap, the latter is expensive. Due to its different use, it is divided into a variety of specifications. According to statistics, in 1985 the world total consumption of silicon metal is about 500000 tons, the silicon which is used for aluminum alloy metal is accounted for about 60%, for the silicone is less than 30%, for semiconductor is accounted for about 3%, others used for steel smelting and precision ceramic.

Metallic silicon can be used for preparing super pure silica, through crushing the raw material, impurity compounds, crystallization purification of three sequential steps of principle, adopts the combination of various procedures operations: the metal silicon broken into fine particles to increase the surface area; pass into the oxygen, chlorine, hydrochloric acid in the silicon particles, conduct combination reaction in the silicon impurity, in order to make the impurities in silicon generated into oxide or chloride by high temperature; use high temperature to make low sublimation temperature chloride evaporation removal, again using the individual element segregation coefficient and oxide eutectic solidification characteristics, with the intermediate technology or directional solidification technique further removal the impurities in silicon. Through the above process and device to remove impurities in silicon, make the silicon metal purified into ultra pure silicon products.

In industry, metal silicon is usually prepared by reduction of silica in an electric furnace carbon. The produced silicon purity is 97~98%, called silicon metal. Then melt it and crystallization, use acid to remove impurities, get the purity of 99.7~99.8% silicon metal. Silicon metal component is silicon, thus having similar properties with silicon. Silicon has amorphous silicon powder and amorphous silicon two allotropes. Amorphous silicon powder is dark gray powder, is in fact a microcrystal. Crystalline silicon has the crystal structure of diamond and semiconductor properties, the melting point is 1410 , boiling point is 2355, the density is 2.32 to 2.34 g / cm 3, Mohs hardness is 7, brittle. Amorphous silicon powder with active chemical properties, can burn in oxygen. It can react with halogen, nitrogen, carbon and other non-metallic at high temperature, also can react with magnesium and calcium, iron and other metals, form of silicide. Amorphous silicon powder is virtually insoluble in all including hydrofluoric acid, inorganic acid and organic acid, but soluble in nitric acid and hydrofluoric acid mixed acid. Concentrated sodium hydroxide solution can dissolve the amorphous silicon powder, release hydrogen. Crystalline silicon is less active, even at high temperatures will not react with oxygen, it will not dissolve in any kind of inorganic acid and organic acid, but soluble in nitric acid and hydrofluoric acid mixed acid and concentrated sodium hydroxide solution.

Silicon metal smelting is a high energy-consuming production, Chinese silicon metal production has long-standing, along with the national energy policy tightening and energy saving, and emission reduction and new energy development advocating, metal silicon smelting has become the primary products and technology, many of Chinese new energy industry construct metal silicon, polycrystalline silicon, monocrystalline silicon, solar cell and other a series of cycle of industrial chainArticle Submission, in the next few years will inevitably affect the development of the field of energy and new energy applications.

Source:http://www.mhcmp.com

Article Tags: Amorphous Silicon Powder, Silicon Metal, Metal Silicon, High Temperature, Amorphous Silicon, Silicon Powder, Hydrofluoric Acid

Source: Free Articles from ArticlesFactory.com

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