karbidien

Karbidien are chemical compounds consisting of carbon combined with elements other than carbon, typically metals. They are commonly called carbides and encompass a range of structures, from binary inorganic carbides to covalent ceramic networks.

Two broad groups are recognized: inorganic binary carbides formed between carbon and metals (for example CaC2, WC, TiC, SiC) and covalent/ceramic carbides in which carbon forms a strong network with elements such as silicon or boron (as in SiC or B4C). Some iron-based carbides, like Fe3C (cementite), are interstitial compounds in metal lattices.

Carbides are typically prepared by carbothermic reduction, reacting metal oxides with carbon at high temperature, or by direct synthesis from elements. Calcium carbide is produced from lime and coke in an electric furnace, and silicon carbide is formed from silica and carbon at high temperature. Many carbides are synthesized as dense ceramics or hard coatings.

Carbides generally possess high melting points, high hardness, and chemical stability. They find use in cutting tools (WC- and TiC-based tools), abrasives (SiC, B4C), wear-resistant coatings, and high-temperature ceramics. Silicon carbide is also used in electronics and power devices due to its wide band gap. Calcium carbide is industrially important as a precursor to acetylene gas.

Natural occurrences of carbides are rare; moissanite is a natural silicon carbide mineral. Most carbides are synthetic. Handling requires caution: carbide powders can be irritants, and calcium carbide reacts with water to release acetylene gas, which is flammable.