Difference between revisions of "Tungsten carbide"

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Tungsten carbide is an inorganic compound of tungsten and carbon , with a chemical formula WC (the most common type) or W₂C.

Properties

Chemical

It is a very inert compound, most of the acids don't attack it except a mixture of HF /HNO3 above room temperature. It reacts with fluorine at room temperature, with chlorine at 400 °C (752 °F) and with hydrogen at its melting point.

When grinded to a fine powder it readily reacts in aqueous solutions of hydrogen peroxide.

Physical

Tungsten carbide is a hard, brittle grey-black solid, insoluble in any solvents and has good chemical resistance. It has a melting point of 2,870 °C (5,200 °F) and a boiling point of 6,000 °C (10,830 °F). Its hardness on the Mohs scale is 9. Tungsten carbine is also an electrical conductor.

Availability

Tungsten carbide can be found in many cutting tools, though it's not pure, it contains cobalt or nickel that serve as a binder.

Certain weights also contain tungsten carbide.

Rotating balls in ballpoint pens are made out of tungsten carbide or its alloy, though their small size means they're not a good source.

Tungsten carbide powder can be bought online.

Preparation

WC can be prepared by reaction of tungsten metal and carbon at 1400–2000 °C.

It can also be produced by heating WO₃ with graphite: directly at 900 °C or in hydrogen at 670 °C following by carburization in Ar at 1000 °C.

Projects

• Make elemental tungsten
• Catalyst
• Tungsten carbide crucible for single crystal growth

Handling

Safety

Tungsten carbide isn't very toxic, but inhalation of its dust can lead to fibrosis.

Storage

No precautions needed.

Disposal

It can sometimes contain small amounts of heavy metals like cobalt, so it shouldn't be thrown readily.

References

Relevant Sciencemadness threads

• Dissolution of Group 6 metals