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What is CaSi?

Calcium silicide (CaSi2), also called calcium disilicide, is an inorganic compound, a silicide of calcium. It is a whitish or dark grey to black solid matter with melting point between 700-935°C. It is insoluble in water, but may decompose when subjected to moisture, evolving hydrogen and producing calcium hydroxide. It decomposes in hot water. It is flammable and may ignite spontaneously in air.

Ferroalloy

EINECS

CAS

Calcium disilicide

Calcium silicide

234-588-7

/234-587-1

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12013-56-8

12013-55-7

12737-18-7

There is a standard analytical methods for the identification of CaSi alloys: DIN 17580.

Composition

Calcium silicide is nominally of composition CaSi2, with small amounts of primary and secondary eutectically precipitated silicon.

The specifications for standard-grade commercial CaSi are summarized hereunder.

	ELEMENTS	PERCENTAGE - %
Calcium	Ca	28 - 32
Silicon	Si	55 - 63
Iron	Fe	Min 4
Aluminium	Al	< 2.5
Carbon	C	1,0 max
Titanium	Ti	0,30 max
Phosphorus	P	0,07 max
Sulfur	S	0,06 max

A number of multicomponent CaSi-based alloys contain up to 30 % aluminium, manganese, barium titanium, magnesium, mischmetal or iron. Those special CaSi-alloys are produced by a combination of carbothermic ore reduction followed by direct alloying.

Note: They are considered for the implementation of REACH as special preparations of CaSi and the additional metal.

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CaSi has been registered on its own for REACH in 2010

the position paper of the CaSi Institute can be found under Position Papers section