Why is alumina widely used in the abrasive industry?

Alumina is widely used in the abrasive industry because it has relatively high hardness, second only to a few materials such as diamond and cubic boron nitride. This high hardness enables it to be used for grinding and polishing various materials. In metal processing, it can be used to grind the surfaces of metal parts to remove burrs, oxide layers and so on, so that the parts can achieve the required roughness and smoothness. In the processing of optical glass, alumina polishing powder can conduct high-precision polishing on the glass surface to make the surface reach the flatness at the optical level, which is used for manufacturing optical instruments such as microscopes, telescopes and camera lenses. Meanwhile, alumina is also widely used in the manufacturing of sandpaper and grinding wheels. The abrasive part of sandpaper often contains alumina, and different particle sizes can be selected according to different grinding requirements. Coarse-grained ones are used for quickly removing the surplus of materials, while fine-grained ones are used for fine grinding and surface finishing. Alumina grinding wheels are widely used in the grinding processes of mechanical processing, such as grinding metal cutting tools, the outer circles and inner holes of mechanical parts. And because of the good wear resistance of alumina, the service life of the grinding wheels is relatively long.