How Abrasive Is Silicon Carbide
Silicon carbide is an extremely hard and sharp abrasive material, with a hardness of about Mohs 9.0 to 9.5, second only to diamond and cubic boron nitride in industrial applications. Silicon carbide abrasive is widely used for grinding, cutting, and surface finishing, especially for hard and brittle materials such as ceramics, glass, and stone.
Key Characteristics
The abrasive characteristics of silicon carbide include high hardness and strong cutting ability, sharp angular grains for fast material removal, a brittle structure that forms new cutting edges during use, and excellent thermal resistance for high-temperature processes.
Why Silicon Carbide Is So Abrasive
The high abrasiveness comes from the combination of hardness and grain structure. Silicon carbide has a very high hardness level, which allows it to cut into hard materials efficiently. At the same time, its angular grain shape creates sharp cutting points that increase cutting speed. During use, silicon carbide abrasive tends to fracture and expose new edges, and this continuous renewal of cutting edges helps maintain performance in grinding and blasting applications.
Silicon Carbide vs Aluminum Oxide
In most cases, silicon carbide is more aggressive than aluminum oxide. Silicon carbide cuts faster and performs better on hard and brittle materials such as glass and ceramics. Aluminum oxide is tougher and more durable, making it more suitable for heavy grinding of metals. In practice, silicon carbide is chosen for speed and sharpness, while aluminum oxide is chosen for durability.
Grades of Silicon Carbide Abrasive
Silicon carbide abrasive is commonly divided into grades based on purity and application. Silicon carbide 75 is lower purity, mainly used in metallurgical applications where cost is a priority. Silicon carbide 88 offers balanced performance, suitable for both abrasive and industrial use. Silicon carbide 90 is higher purity, providing stronger and more consistent abrasive performance. For many applications, 200 mesh silicon carbide powder is widely used because it offers good control over cutting and surface finish.
Best Applications and Limitations
Due to its high abrasiveness, silicon carbide is best suited for glass and ceramic grinding, stone and refractory surface processing, non-ferrous metals such as aluminum, and sandblasting and surface preparation. It may be too aggressive in fine finishing, where it can produce a rough surface; in soft materials, where it may remove material too quickly; and in applications requiring long abrasive life, where it may wear faster.
Frequently Asked Questions
How abrasive is silicon carbide? Extremely abrasive, with a hardness of about Mohs 9.0 to 9.5, one of the hardest industrial abrasives.
Is silicon carbide more abrasive than aluminum oxide? Yes, it cuts faster and suits hard and brittle materials, while aluminum oxide is more durable for heavy grinding.
What is silicon carbide best for? Grinding and processing hard and brittle materials such as glass, ceramics, stone, and non-ferrous metals like aluminum.
When should silicon carbide not be used? For soft materials or fine finishing where it can be too aggressive and produce a rough surface.
What are the differences between silicon carbide 75, 88, and 90? Silicon carbide 75 is lower purity, mainly for metallurgical applications where cost is a priority; 88 offers balanced abrasive and industrial performance; 90 is higher purity with stronger and more consistent abrasive performance.
Why does silicon carbide keep cutting during grinding? During use, silicon carbide tends to fracture and expose new sharp edges, and this continuous renewal of cutting edges helps maintain performance in grinding and blasting applications.
