Glossary

Silicon carbide (SiC) is a compound of silicon and carbon that is recognized for its exceptional hardness, thermal stability, and chemical resistance. While it occurs naturally in extremely rare mineral forms such as moissanite, it is primarily produced synthetically and has become one of the most important advanced ceramics in modern industry. Its unique combination of properties allows it to be used both as a high-performance structural material and as a semiconductor in power electronics.

Silicon carbide’s strength comes from its crystalline structure, in which silicon and carbon atoms alternate in strong covalent bonds. This gives it a hardness of about 9–9.5 on the Mohs scale, placing it just below diamond and cubic boron nitride. Unlike many ceramics, it also has high thermal conductivity, which allows it to transfer heat efficiently. SiC can withstand temperatures above 1,600 °C (2,912 °F) without losing strength and is highly resistant to oxidation, corrosion, and chemical attack. In addition, certain forms of SiC function as semiconductors, offering a wide bandgap, high voltage resistance, and efficiency that make them highly valuable in advanced electronics.

The material is typically manufactured through the Acheson process, in which a mixture of silica sand (SiO₂) and carbon, often from petroleum coke, is heated in an electric resistance furnace at temperatures between 2,000–2,500 °C (3,632–4,532 °F). The reaction produces silicon carbide crystals, which can then be ground into abrasive powders, sintered into ceramic components, or grown into wafers for use in electronics.

Applications of silicon carbide are diverse. Its hardness makes it ideal for abrasives such as grinding wheels, sandpapers, and polishing compounds, as well as cutting tools that must endure high wear. In ceramics and refractories, it is used for furnace linings, kiln shelves, and crucibles that must tolerate high heat. In the electronics sector, silicon carbide is increasingly important as a semiconductor material for high-performance power devices used in electric vehicles, solar inverters, and high-frequency systems. The automotive industry uses SiC in performance brake discs, clutches, and heat exchangers, while its lightweight hardness makes it suitable for armor in protective vests and vehicles.

The advantages of silicon carbide include its extreme hardness and wear resistance, ability to withstand very high operating temperatures, chemical stability, corrosion resistance, and efficiency in conducting both heat and electricity in specialized applications. However, it does have limitations. It is brittle compared to metals and can fracture under sudden impact or shock loads. Production costs, particularly for semiconductor-grade SiC, are relatively high. Additionally, its hardness requires specialized equipment and processes for shaping, machining, and finishing. Despite these challenges, silicon carbide remains an essential material for industries demanding high performance in extreme environments.