Silicon Carbide Properties and Applications

Silicon carbide (SiC), also known as carborundum, is a compound of silicon and carbon that forms a robust and industrially significant crystal lattice. Known for its hardness and thermal conductivity properties, SiC stands out as a semiconductor and ceramic material used across a myriad of industrial applications. Here, we delve into the properties of silicon carbide and explore its varied applications in different sectors.

Introduction to Silicon Carbide

Silicon carbide, known in mineral form as moissanite, is a semi-transparent, crystalline compound that occurs naturally, albeit very rarely. It can also present in various colors due to impurities. It is valued for its strength, hardness, and thermal properties, making it ideal for high-voltage and high-temperature applications.

Properties of Silicon Carbide

Silicon carbide's properties are what make it such a valuable material across multiple industries. Covered below are some of the essential characteristics that define its usage and desirability:

• Robust Crystal Structure

  SiC consists of a crystalline structure of carbon atoms arranged in tetrahedrons with a silicon atom at the center, exhibiting polymorphic qualities based on its different crystalline structures. This strong bond grants it excellent hardness and strength.

• High Hardness

  With a Mohs hardness rating close to that of diamond, SiC can readily be used for applications that require a high level of abrasion resistance such as cutting tools and abrasive blasting.

• High-Temperature Resistance

  One remarkable feature of silicon carbide is its ability to endure high temperatures — it begins to decompose at temperatures as high as 2000°C. This makes it apt for use in refractory materials and other applications involving extreme heat.

• Electrical Conductivity

  Silicon carbide behaves as an electrical insulator when pure. However, its semiconducting properties can be manipulated by introducing impurities. This duality in behavior makes it versatile for different electrical applications.

• Chemical Stability

  Chemically, SiC is inert and boasts high corrosion resistance. It can withstand exposure to various acids and bases without degradation, which is why it sees usage in environments where chemical stability is paramount.

Production of Silicon Carbide

The rarity of natural silicon carbide necessitates its synthetic manufacture, commonly achieved through the Acheson method. This synthesis involves subjecting a mixture of quartz sand and finely ground petroleum coke to high temperatures between 1700 to 2500°C. The resulting crystalline SiC can then be sorted, crushed, milled, or chemically treated for its intended application.

Applications of Silicon Carbide

Thanks to its combination of exceptional properties, SiC serves a wide range of applications:

• As an Abrasive Material

  Silicon carbide is notably used in abrasive machining processes like grinding, honing, and water-jet cutting. Its high hardness allows it to excel in shaping and finishing metals and non-metals alike.

• High-Temperature Gas Sensors

  In hostile environments, such as extreme heat and corrosion, SiC makes for robust gas sensors that can withstand the demanding conditions prevalent in chemical production and engine testing.

• Electronics and Semiconductors

  SiC is integral to the semiconductor industry, offering high voltage resistance which is essential in the development of energy-efficient electronics, electric vehicles, and solar inverters. Its performance is particularly superior in systems that surpass 1000V thresholds and even outperforms alternatives like gallium nitride in some cases.

• Refractory Materials

  With its high-temperature resistance, silicon carbide is used in the production of refractory bricks and materials that line furnaces and kilns.

Conclusion

The combination of strength, temperature resistance, and electrical properties makes silicon carbide a material with great potential. With the increasing demand for materials that can withstand high-temperature conditions in various industries, the application of silicon carbide will become more widespread.