SILICON, a tetravalent metalloid, is a chemical element with the symbol Si and
atomic number 14.
Elemental silicon also has a large impact on the modern world economy. Although most free silicon is used in the steel refining, aluminum-casting, and fine chemical industries (often to make fumed silica), the relatively small portion of very highly purified silicon that is used in semiconductor electronics (< 10%) is perhaps even more critical. Because of wide use of silicon in integrated circuits, the basis of most computers, a great deal of modern technology depends on it.
Silicon is a solid at room temperature, with relatively high melting and boiling points of 1414
and 3265 degrees Celsius respectively. It has a greater density in a liquid state than a solid
With a relatively high thermal conductivity of 149 W•m−1•K−1, silicon conducts heat well and as a result is not often used to insulate hot objects. In its crystalline form, pure silicon has a gray color and a metallic luster.
Most metallurgical silicon metal is used as an alloying agent in the aluminium industry due to its ability to increase the strength of aluminium. Demand from the aluminium industry has grown steadily in recent years due to increased usage of aluminium in structural engineering, aircraft manufacture and the automotive industry. Aluminium alloys are lighter and more resistant to corrosion than carbon-steel and can be made by addition of metals such as copper, zinc, magnesium, manganese as well as silicon.
Elemental silicon not alloyed with significant quantities of other elements, and usually > 95%,
is often referred to loosely as silicon metal. Metallurgical grade silicon is commercially
prepared by the reaction of high-purity silica with wood, charcoal, and coal in an electric arc
furnace using carbon electrodes.
It being the carbo thermic reaction of silica (quartz) in an electric arc furnace using carbon electrodes where the temperature in the main reaction zone of temperatures exceeds 1800ºC
At temperatures over 1,900 °C (3,450 °F), the carbon in the aforementioned materials and the silicon undergo the chemical reaction
SiO2 + 2 C → Si + 2 CO.
Liquid silicon collects in the bottom of the furnace, which is then drained and cooled. The silicon produced this manner is called metallurgical grade silicon and is at least 98% pure.
Using this method, silicon carbide (SiC) may also form from an excess of carbon in one or both of the following ways:
SiO2 + C → SiO + CO or SiO + 2 C → SiC + CO.
However, provided the concentration of SiO2 is kept high, the silicon carbide can be eliminated by the chemical reaction
2 SiC + SiO2 → 3 Si + 2 CO
As noted above, metallurgical grade silicon "metal" has its primary use in the aluminum casting industry to make aluminum-silicon alloy parts. The remainder (about 45%) is used by the chemical industry, where it is primarily employed to make fumed silica.
APPLICATIONS: Adding Silicon Metal to aluminium alloys makes them strong and
light. As a result they are increasingly used in the automotive industry to replace heavier cast
iron components. This allows weight reductions, a reduction in fuel consumption, increased
efficiencies and subsequent benefits to the environment by reducing the greenhouse gas emissions
and conserving fossil fuels.
There is increasing demand for Silicon Metal from the solar power generating industry where solar panels are made from silicon, which use the sun’s energy to produce domestic and industrial electricity. Silicon based polymers are also used as alternatives to hydrocarbon based products. They can appear in many every day products such as lubricants, greases, resins, skin and hair products. A more well known use of silicon is silicon chips, produced from semi-conductor grade silicon they are components in many every day electronic devices.
Type: 2202, 3303, 3205, 411, 521, 441, 553
Size: 10-100 mm