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 silicides. 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 steels, stainless steels, and other ferrous alloys for its deoxidizing properties, to prevent loss of carbon from the molten steel (so called blocking the heat) ferromanganese, spiegeleisen, silicides 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 electromotors 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 prealloys like magnesium ferrosilicon (FeSiMg), used for modification of melted malleable iron; FeSiMg contains between 3-42% of magnesium and small amounts of rare earth metals. Ferrosilicon is also important as an additive to cast irons for controlling the initial content of silicon.
