Silicon Carbide (SiC) Abrasives | CRATEX Abrasives

Silicon Carbide (SiC) or carborundum is a unique compound of silicon and carbon and is a sharp and hard synthetic mineral. It’s one of the minerals of intermediate hardness, since it is located between 9 and 9.5 on the Mohs scale (for reference, diamond is a 10, and corundum a 9). It is also a mineral that does occur naturally but is extremely rare – it is found in small quantities and in a limited number of places.

The mass production of the synthetic silicon carbide powder began in 1893, and the synthetic form has been used as an industrial abrasive ever since. It is commonly produced in electrical resistance furnaces by the Acheson process (the process is named after its inventor, E.G. Acheson). It develops as a solid block that gets crushed, classified, sometimes milled and sometimes chemically treated.

What is interesting about it, is that it is one of the few minerals that was created synthetically first, and only later discovered in nature. Namely, it was discovered in its natural form known as moissanite by the Nobel prize winning chemist, H. Moissan in 1905 in Diablo Canyon in Arizona, United States. Since it discovery, moissanite was not found in nature in larger quantities, and obtaining it for industrial use was difficult and rather costly. Therefore, the synthetic form remained the widely used form until this day. Since it is a transparent mineral that is almost as hard and brilliant as diamond, moissanite is often used as a gemstone instead.

Silicon carbide is a ceramic material has high-thermal conductivity, low thermal expansion and is therefore, extremely resistant to thermal shock. In addition, low density, high strength and hardness, high resistance to wear and superior chemical inertness (only inert to all alkalis and acids), make it a crucial material in industries, such as wear-resistant mechanical parts, aerospace, industrial furnaces and electronics. Although it has a high level of hardness, silicon carbide is more brittle than other abrasives - its grains break off easily enabling it to maintain sharp cutting action.

Due to its properties, it is used for grinding hard, durable materials, such as granite, chilled iron and marble, and for cutting materials such as copper, leather, fiber and rubber. It is also mixed with other materials to form abrasive compounds that are used in lapping and is used in combination with cloth backings in the production of abrasive disks, belts and sheets.

Along with the synthetic diamond, silicon carbide today is one of the most used abrasives in numerous industries and inevitable tool in most craftsman workshops. Thanks to its hardness, it is used in various machining processes such as grinding, honing, sandblasting and water-jet cutting.

What affects the wheel speed, its cutting power and the finish is the type of the bond agent that it’s used to hold the abrasive grains. Various types of bonds, such as vitrified, resinoid and rubber, will determine the exact wheel’s performance and application.