FERROSILICON
A high-silicon master alloy used for making silicon steels, and for adding silicon to transformer irons and steels. It is made in the electric furnace by fusing quartz or silica with iron turnings and carbon. It is marketed in various grades with from 15 to 90% silicon. The silicon forms a chemical combination with the iron, but the alloys having more than about 30% silicon are fragile and unstable. The silicon also causes the carbon to be excluded in graphite flakes. The alloys of high silicon content are called silicon metal. One producer markets two grades, 15 and 45% silicon, while another has 15, 50, 75, 85, and 90% grades. Grades with silicon from 80 to 95% are marketed for use where small ladle additions are made for producing high-silicon steels, and for producing hydrogen by reaction with caustic soda. The alloy is marketed in lumps or crushed form. Silicon is often added to steels in combination alloys with deoxidizers or other alloying elements. Ferrosilicon aluminum, containing about 45% silicon and 12 to 15 aluminum, is a more effective deoxi-dizer for steel than aluminum alone. It is also used for adding silicon to aluminum casting alloys. Silvaz is a ferrosilicon aluminum containing also vanadium and zirconium. The alloy serves as a deoxi-dizer, fluxes the slag inclusions, and also controls the grain size of the steel. Simanal is a deoxidizing alloy containing 20% each of silicon, aluminum, and manganese. Alsifier contains 40% silicon, 20 aluminum, and 40 iron. The aluminum and silicon are in the form of an aluminum silicate which forms a slag that is eliminated during the teeming of the steel. Alsimin is a Swiss ferrosilicon aluminum with 50% aluminum. Silicon aluminum is a master alloy for adding silicon to aluminum alloys, and it does not contain iron. A 50–50 silicon aluminum has a melting point of 1920°F (1049°C), but is soluble in aluminum at 1275°F (690°C). It comes in pyramid waffle form for breaking into small lumps.

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