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Classification Of Carbides
Mar 21, 2018

Fold-filled carbides

Also known as metal carbides, mainly d transition elements, in particular VIB, VIIB group and iron compounds and carbon formed binary compounds. Its structural feature is that carbon atoms are filled in the tetrahedral holes of the closely packed metal lattice and do not affect the conductivity of the metal. For a metal with an atomic radius greater than 1.3 angstroms, carbon atoms do not deform the metal lattice and only make the crystal lattice more compact. These metal carbides have extremely high melting points and hardness, such as niobium carbide (see niobium) and tungsten carbide. For a metal with an atomic radius of less than 1.3 angstroms, the carbon atom deforms the original metal lattice, and the atomic chain of carbon penetrates through the deformed metal structure, such as the carbides of chromium, manganese, iron, cobalt, and nickel. The nature of the carbides of these metals is between ionic and inter-filled types, with a high melting point and hardness, and can also be decomposed by water and acids to form a mixture of hydrocarbons and hydrogen.

Folded covalent carbides

Mainly silicon and boron carbides, such as silicon carbide and boron carbide (see boron). In these carbides, carbon atoms are covalently bonded to silicon and boron atoms, which are atomic crystals. They have high hardness, high melting point and chemical stability.

Processes and applications, these three types of carbides can be made by reacting metals, silicon, boron or their oxides with carbon or hydrocarbons at a high temperature of 2000°C.

Folded Ionic Carbide

Calcium carbide is most useful in ionic carbides and is mainly used as a raw material for acetylene. Interstitial carbides are mainly used as special structural materials and high-speed cutting tool materials that are resistant to high temperatures and high hardness, such as tantalum carbide and tungsten carbide. Covalent carbides are mainly used as abrasives, such as silicon carbide and boron carbide.





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