What Is Silicon Carbide?

Silicon carbide (SiC) is an extremely hard and wear-resistant ceramic material used in automotive brakes and clutches for long-lasting parts.

Mechanical properties include low thermal expansion and high hardness.

These qualities make the material well-suited to power electronics, where its wider bandgap enables higher operating voltages than traditional silicon inverters.

Hardness

Silicon Carbide (SiC) is one of the hardest synthetically produced materials, second only to boron carbide and diamond. With an exceptional wear resistance rating and thermally stable properties, SiC makes an ideal material choice for applications requiring high endurance or temperature resistance.

SiC powder forms crystalline structures ranging in color from yellow-green to bluish-black depending on its purity. SiC is insoluble in water but somewhat more so in alkalines or iron.

SiC ceramics can be significantly increased by adding soft phases such as GNPs and Ti, or by sintering with materials such as niobium carbide to increase density [17], leading to higher thermal conductivity of the finished product and increased hardness (grain size increases and reaction bonding increases with temperature). However, maximum temperatures should never be exceeded as otherwise SiC particles may lose their crystal structure and become fragile over time.

Thermal Conductivity

Silicon carbide’s superior thermal conductivity makes it the go-to material for applications requiring fast, reliable performance at extremely high temperatures and voltages. Its voltage resistance is ten times higher than silicon’s, outperforming gallium nitride in systems operating above 1000V.

Silicon carbide’s wide bandgap property allows it to perform well in devices that are sensitive to temperature and voltage variations, such as those used to power electric vehicles. Furthermore, silicon carbide’s wide-bandgap also protects it against corrosion and oxidation.

Silicon carbide can be manufactured into various shapes and sizes depending on its intended application. Most commonly it’s manufactured as a fine powder that’s mixed with non-oxide sintering aids to form a paste which can then be compacted through extrusion, injection molding or extrusion molding for compacting or shaping purposes. Other methods may involve chemical vapor deposition or carbon-based synthesis processes that produce cubic SiC that serves as an abrasive material during grinding, honing and water jet cutting processes.

Thermal Expansion

Silicon carbide is a tough material with excellent thermal shock resistance, making it suitable for various abrasive machining processes such as grinding, honing and water-jet cutting. Furthermore, its relatively low coefficient of thermal expansion ensures it remains dimensionally stable over time; making silicon carbide an indispensable abrasive in modern lapidary.

Silicon carbide possesses a close-packed structure composed of two primary coordination tetrahedra made up of four silicon and four carbon atoms each that are covalently bonded with one another to form close-packed polytype structures.

Silicon carbide’s crystal structure can be altered to alter its elastic properties, providing control of its elastic properties. First-principles calculations using density functional theory were carried out to investigate how various defects such as vacancy, interstitial and antisite defects affect elastic constants of SiC and ZrC; for instance the dominant VC defect dramatically reduces C44 while other defects had minimal influence such as VSi and Sit.

Electrical Conductivity

Silicon carbide consists of hexagonal crystals joined together with strong covalent bonds, producing a durable material used in applications as diverse as sandpaper, grinding wheels and cutting tools since its discovery during the late 19th century. More recently it’s also been employed in industrial furnaces’ refractory linings, wear-resistant parts for pumps and rocket engines and as semiconducting substrate for light emitting diodes (LED).

Silicon carbide in its pure state is an electrical insulator; however, with the controlled addition of impurities known as dopants it can transform into an electrical semiconductor. Nitrogen and phosphorus dopants create N-type semiconductor properties; aluminum, boron or gallium dopants transform it into P-type properties.

Silicon carbide’s wide bandgap allows it to conduct electricity more efficiently than traditional semiconductors, leading to devices with smaller, faster running time, higher temperature resistance and voltage tolerance; and greater power handling capacities which translate to reduced costs across many applications.

Scroll to Top