Silicon carbide

Silicon carbide

Silicon carbide sample.
Names
IUPAC name Silicon carbide
Other names Carborundum Moissanite
Identifiers
Jmol-3D images	Image
SMILES [C-]#[Si+]
Properties
Chemical formula	SiC
Molar mass	40.10 g/mol
Appearance	Black lustrous solid
Density	3.21 g/cm3
Melting point	2,730 °C (4,950 °F; 3,000 K) (decomposes)
Boiling point	Decomposes
Solubility in water	Insoluble
Solubility	Reacts with molten alkali Insoluble in virtually all solvents
Vapor pressure	~ 0 mmHg
Hazards
Safety data sheet	ScienceLab
Flash point	Non-flammable
Related compounds
Related compounds	Silicon boride Silicon dioxide Silicon nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Silicon carbide, also known as carborundum is a compound of silicon and carbon with chemical formula SiC, mainly used as an abrasive. Silicon carbide occurs naturally as very rare mineral moissanite.

Properties

Chemical

Silicon carbide resists the attack of many acids due to the formation of a thin layer of silicon dioxide, however, SiC will dissolve in molten alkali.

Physical

Silicon carbide is a black solid, with a density of 3.21 g/cm³, odorless, with a high melting point of 2,730 °C. It is extremely hard solid (9-9,5 on Mohs scale). SiC is insoluble in all solvents.

Availability

Silicon carbide is often present in abrasive materials and some semiconductors.

It can be also bought as moissanite which is highly attractive synthetic gem and is being used as a cheaper replacement for diamonds in jewellery.

Preparation

Because of the rarity of natural moissanite, most silicon carbide is synthetic. However the preparation of SiC is too difficult for most amateur scientists. The simplest manufacturing process is to combine silica sand and carbon in an Acheson graphite electric resistance furnace at a high temperature, between 1,600 °C (2,910 °F) and 2,500 °C (4,530 °F). Fine SiO² particles in plant material (e.g. rice husks) can be converted to SiC by heating in the excess carbon from the organic material. The silica fume, which is a byproduct of producing silicon metal and ferrosilicon alloys, also can be converted to SiC by heating with graphite at 1,500 °C (2,730 °F).

Projects

• Silicon carbide crucible
• Abrasive material
• Mineral collecting (moissanite)

Handling

Safety

Silicon carbide is non-flammable and non-explosive. In bulk form is practically inert, while the powdered form is more hazardous:

Effects of Exposure: To the best of our knowledge the chemical, physical and toxicological properties of silicon carbide have not been thoroughly investigated and reported. Silicon carbide is a nuisance dust capable of producing nonprogressive pulmonary fibrosis. Silicon carbide implants have caused tumors in laboratory animals.

Acute Effects: Inhalation: May cause irritation. Ingestion: No acute health effects recorded. Skin: May cause abrasive irritation. Eye: May cause abrasive irritation.

Chronic Effects: Inhalation: May cause pneumoconiosis. No other chronic health effects recorded.

Target Organs: No target organs recorded. Medical Conditions Generally Aggravated by

Exposure: Pre-existing respiratory disorders.

Carcinogenicity: NTP: No IARC: No OSHA: No

Storage

Silicon carbide is very stable and doesn't require any special storage.

Disposal

Silicon carbide isn't harmful to environment, so it's safe to dump it with normal trash or into the soil.

References

Relevant Sciencemadness threads

• Microwave Kiln "Microkiln"
• SiC electrodes