Ferrosilicon
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201322872
2008-03-27T14:09:28Z
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Date the maintenance tags or general fixes
[[Image:Ferrosilicon.JPG|thumb|250px|Ferrosilicon alloy]]
'''Ferrosilicon''', or '''ferrosilicium''', is a [[ferroalloy]] an alloy of [[iron]] and [[silicon]] with between 15 and 90% silicon. It contains a high proportion of [[iron silicide]]s. Its melting point is about 1200 °C to 1250 °C with a boiling point of 2355 °C. It also contains about 1 to 2% of [[calcium]] and [[aluminium]].
Ferrosilicon is used in [[steelmaking]] and [[foundries]] as a source of silicon in production of [[carbon steel]]s, [[stainless steel]]s, and other ferrous [[alloys]] for its [[deoxidizing]] properties, to prevent loss of [[carbon]] from the molten steel (so called ''blocking the heat''); [[ferromanganese]], [[spiegeleisen]], [[silicide]]s of [[calcium]], and many other materials are used for the same purpose. It can be used to make other ferroalloys. Ferrosilicon is also used for manufacture of [[silicon]], corrosion-resistant and high-temperature resistant ferrous silicon alloys, and [[silicon steel]] for [[electromotor]]s and [[transformer]] cores. In manufacture of [[cast iron]], ferrosilicon is used for inoculation of the iron to accelerate graphitization. In [[arc welding]], ferrosilicon can be found in some electrode coatings.
Ferrosilicon is a basis for manufacture of [[prealloy]]s like [[magnesium ferrosilicon]] (FeSiMg), used for modification of melted [[malleable iron]]; FeSiMg contains between 3-42% of [[magnesium]] and small amounts of [[Rare earth element|rare earth]] metals. Ferrosilicon is also important as an additive to cast irons for controlling the initial content of silicon.
Ferrosilicon is also used in the [[Pidgeon process]] to make magnesium from [[dolomite]].
In contact with water, ferrosilicon may slowly produce [[hydrogen]].
Ferrosilicon is produced by reduction of [[silica]] or [[sand]] with [[coke (fuel)|coke]] in presence of scrap [[iron]], millscale, or other source of iron. Ferrosilicons with silicon content up to about 15% are made in [[blast furnace]]s lined with acid [[fire brick]]s. Ferrosilicons with higher silicon content are made in [[electric arc furnace]]s. An overabundance of silica is used to prevent formation of [[silicon carbide]]. [[Microsilica]] is a useful byproduct.
The usual formulations on the market are ferrosilicons with 15, 45, 75, and 90% of silicon. The remainder is iron, with about 2% of other elements like aluminium and calcium.
Its [[CAS number]] is {{CASREF|CAS=8049-17-0}}.
A mineral [[perryite]] is similar to ferrosilicon, with its composition Fe<sub>5</sub>Si<sub>2</sub>.
Ferrosilicon is used by the military to quickly produce [[hydrogen]] for [[balloon (aircraft)|balloons]] by the '''ferrosilicon method'''. The chemical reaction uses [[sodium hydroxide]], ferrosilicon, and water. The generator is small enough to fit a truck and requires only a small amount of electric power, the materials are stable and not combustible, and they do not generate hydrogen until mixed.<ref>[http://naca.larc.nasa.gov/reports/1920/naca-report-40/]{{Dead link|date=March 2008}}</ref>
The melting point and [[density]] of ferrosilicon is dependent on its silicon content.
{| border=1 cellpadding=5 cellspacing=0 style="border: 1px #aaa solid; border-collapse: collapse; text-align: center;"
!Name
!Si content<br>[%]
!Melting point<br>[°C]
!Density<br>[g/cm³]
|-
|FeSi 45
|45
|1215 - 1300
|5.1
|-
|FeSi 75
|75
|1210 - 1315
|2.8
|-
|FeSi 90
|90
|1210 - 1380
|2.4
|}
== References ==
{{reflist}}
== External links ==
* [http://www.turnstone.ca/silicide.htm Silicides in fulgurites and ferrosilicon]
[[Category:Ferroalloys]]
[[Category:Silicides]]
[[Category:Iron compounds]]
[[Category:Deoxidizers]]
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