Calcium silicide also called calcium disilicide, is an inorganic compound, a silicide

Silicide

A silicide is a compound that has silicon with more electropositive elements.Silicon is more electropositive than carbon. Silicides are structurally closer to borides than to carbides....

 of calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

. It is a whitish or dark grey to black solid matter with melting point 1033°C. It is insoluble in water, but may decompose when subjected to moisture, evolving hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 and producing calcium hydroxide

Calcium hydroxide

Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a colourless crystal or white powder and is obtained when calcium oxide is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or...

. Decomposes in hot water. It is flammable and may ignite spontaneously in air. Its CAS number is .

Industrial calcium silicide usually contains iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 and aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 as the primary contaminants, and low amounts of carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 and sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

.

Calcium silicide is used for manufacture of special metal alloy

Alloy

An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

s, eg. for removing phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 and as a deoxidizer

Deoxidizer

A deoxidizer is a chemical used in a reaction or process to remove oxygen. In comparison with antioxidants, deoxidizers are not used for stabilization during storage but for oxygen removal during manufacture...

.

In pyrotechnics

Pyrotechnics

Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...

, it is used as fuel to make special mixtures, eg. for production of smoke

Smoke

Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires , but may also be used for pest...

s, in flash compositions, and in percussion cap

Percussion cap

The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...

s. Specification for pyrotechnic calcium silicide is MIL-C-324C. In some mixtures it may be substituted with ferrosilicon

Ferrosilicon

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...

. Silicon-based fuels are used in some time delay mixtures, eg. for controlling of explosive bolts, hand grenades, and infrared decoys. Smoke compositions often contain hexachloroethane

Hexachloroethane

Hexachloroethane, also known as perchloroethanes , C2Cl6, is a colorless solid at room temperature which is used by the US Military in smoke compositions, e.g...

; during burning they produce silicon tetrachloride

Silicon tetrachloride

Silicon tetrachloride is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.-Preparation:...

, which, like titanium tetrachloride

Titanium tetrachloride

Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is an unusual example of a metal halide that is highly volatile...

 used in smoke-screen

Smoke-screen

thumb|right|205px|A [[U.S. Army]] [[Humvee]] laying a smoke screenA smoke screen is smoke released to mask the movement or location of military units such as infantry, tanks, aircraft or ships....

s, reacts with air moisture and produces dense white fog. Gum arabic

Gum arabic

220px|thumb|right|Acacia gumGum arabic, also known as acacia gum, chaar gund, char goond, or meska, is a natural gum made of hardened sap taken from two species of the acacia tree; Acacia senegal and Acacia seyal...

 is used in some mixtures to inhibit calcium silicide decomposition. http://groups.google.com/group/rec.pyrotechnics/browse_thread/thread/dc002fbb39b31aeb/63f84b3de3764a8e?lnk=raot

Self-heating can

Self-heating can

A self-heating can is an enhancement of the common food can. Self-heating cans have dual chambers, one surrounding the other. The inner chamber holds the food or drink, and the outer chamber houses chemicals that undergo an exothermic reaction when combined...

s of military food rations developed during the World War II used a thermite

Thermite

Thermite is a pyrotechnic composition of a metal powder and a metal oxide that produces an exothermic oxidation-reduction reaction known as a thermite reaction. If aluminium is the reducing agent it is called an aluminothermic reaction...

-like mixture of 1:1 iron(II,III) oxide

Iron(II,III) oxide

Iron oxide is the chemical compound with formula Fe3O4. It is one of a number of iron oxides, the others being iron oxide , which is rare, and iron oxide also known as hematite. It occurs in nature as the mineral magnetite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙...

and calcium silicide. Such mixture, when ignited, generates moderate amount of heat and no gaseous products. http://www.du.edu/~jcalvert/phys/bang.htm

There is also a calcium silicide CaSi, CAS number . See also CAS number .