Silicon metal components
Silicon metal component is an important physical property of silicon metal. As the silicon metal more and more applied in people's daily lives and industrial production, the studies on silicon metal has very important significance.
Silicon metal is the product composed of quartz and coke smelting in electric furnace, the main component of silicon content is around 98%, the remaining impurities are iron, aluminium, calcium and so on. Silicon metal (also known as Silicon in China) is a product name appears in 60 medium-term of this century. Its emergence is related to the rise of semiconductor industry. At present, international practice is divided silicon into metallic silicon and silicon products. Semiconductor silicon used for the production of semiconductor devices high-purity silicon metal. Are based on polycrystalline and single crystal form for sale, the price the former is cheap, the latter is expensive.
The classification of silicon metal is usually according to the three main impurities of iron, aluminium and calcium content in silicon metal component. Industrially, silicon metal is usually determined by carbon reducing silica in electric furnace. The purity of silicon produced by this method is 97~98%, called silicon metal. Then recrystallize after melting, remove impurities with acid to get silicon metal, which the purity is 99.7~99.8%.
Silicon metal composition was mainly the silicon, so that have similar property with silicon. Silicon has amorphous silicon powder and crystalline silicon two allotropes. Amorphous silicon powder is dark gray powder, is actually a micro-crystal. Crystal silicon has diamond crystal structure and semiconductor properties. Amorphous silicon powders chemical property is lively, intense burning in oxygen. Can react with halogens, nitrogen, carbon and other non-metallic at high temperature, also can react with magnesium, calcium, iron and other metals to generate silicide. Amorphous silicon powder almost insoluble all inorganic acids and organic acids except hydrofluoric acid, but can be dissolved in the mixture of nitric acid and hydrofluoric acid. Concentrated sodium hydroxide solution can dissolve the amorphous silicon powder, releasing hydrogen gas. Crystal silicon is less lively, even if in the heat were not combined with oxygen, it also can not soluble in any inorganic acids and organic acids, but dissolve in the mixture of nitric acid and hydrofluoric acid and concentrated sodium hydroxide solution.
Semiconductor silicon used for producing semiconductor devices high-purity silicon metal. Because of their different uses, they can be divided into a variety of specifications. According to metal powder supplier research, in 1985, the world consumes about 500,000 tons of silicon metal, of which used for aluminum alloy is accounted 60%, used for silicone is less than 30%, for semiconductors accounted for about 3% and the rest used for iron and steel making and precision ceramics.
The content of silicon in the Earth's crust is only second to oxygen, up to 25.8%. Silicon metal in nature is mainly in the form of combining with oxygen into silicon dioxide, or metal silicates, the purest silica mineral is quartz and silica. The property of silicon metal is closed to silicon, germanium, tin, lead. Silicon is extensively used for ferrosilicon smelting, as the alloying element in iron and steel industry, as a reducing agent in many kinds of metals smelting. Silicon metal is also a good set of aluminum alloy, the vast majority casting aluminum alloys were containing silicon metal. Silicon metal is also the raw materials of electronics industry ultrapure silicon, the electronic devices made by ultra pure semiconductor silicon have the advantages of small size, light weight, high reliability and long life, etc.
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