Sapphire crystal chemical composition is Al2O3, Mohs hardness of 9.0, with excellent mechanical, thermal, optical, electrical and chemical stability, etc. Therefore, it is widely used in uv to infrared spectral region optical window elements, micro-electronic circuit insulation substrate, LED chip substrate, laser matrix materials, precision instruments, gyroscopes, satellites and the optical shield on the rocket missile, etc..

The main purpose of sapphire lapping is to remove the surface cut and uneven damage layer, improve the wafer flatness, reduce the surface roughness and meet the requirements of pre-polishing.

Boron carbide abrasive has obvious advantages over diamond abrasive in reducing the depth of sapphire subsurface damage. Boron carbide has high hardness (Mohs hardness 9.36, Second only to diamond and cubic boron nitride), low density (theoretical density is only 2.52 g/cm3), high melting point (2 450℃), excellent wear resistance, good thermal neutron absorption and other excellent properties, It is widely used as mechanical grinding material, engineering ceramic material, military armor material, nuclear reactor shielding material and high-grade refractory material, etc. The demand of boron carbide powder increases with the increase of sapphire chip dosage.