The application of boron carbide as an abrasive is mainly for the grinding and polishing of sapphire. Among the superhard materials, the hardness of boron carbide is better than that of alumina and silicon carbide, second only to diamond and cubic boron nitride. Sapphire is the most ideal substrate material for practical applications such as semiconductor, light-emitting diodes (LEDs), large-scale integrated circuits SOI and SOS, and superconducting nanostructure films. The smoothness of the surface should be very high, and it must reach the level of ultra-smooth as well as no damage. Due to the high strength and hardness of sapphire crystal (Mohs hardness of 9), it has brought great difficulties to processing enterprises.

From the perspective of materials and grinding academia, the best materials for processing and grinding sapphire crystals are synthetic diamond, boron carbide, silicon carbide, and silicon dioxide. Synthetic diamond’ s high hardness (Mohs hardness of 10) will scratch the surface when grinding sapphire wafers, affecting the light transmittance of the wafers, and is expensive. The effect of silicon carbide is not good enough. The roughness is usually high, and the flatness is poor.  As for silica, the hardness of silica is not enough (Mohs hardness is 7) and the grinding force is poor, which is time-consuming and labor-intensive in the grinding process. Therefore, boron carbide abrasive (Mohs hardness 9.3) has become the most ideal material for processing and grinding sapphire crystals, and has excellent performance in the double-sided grinding of sapphire wafers and the thinning and polishing of sapphire-based LED epitaxial wafers.

It is worth mentioning that when the temperature of boron carbide is above 600 ℃, the surface will be oxidized into a B2O3 film, which will soften it to a certain extent. Therefore, it is not suitable for dry grinding at high temperature in abrasive applications, but only for polishing liquids.