Abrasives
Abrasives can be simply described as substances that are hard and sharp enough to change the shapes or surfaces of other objects by actions of grinding, cutting, rubbing and polishing. Abrasives can be natural or artificial but they should be hard and sharp for such purposes. Since there were civilization some thousands years ago, human beings used abrasives to improve and change their lives. At very earliest stages, they used simply everything that was available like stones and shells. Later on people used big quantities of some hard minerals like garnet, quartz, emery and corundum. Until today, abrasives are still being used by people every day - spongy pads to clean kitchen wares; anti-slip tapes used in stair ways; sanding sticks for polishing nails and even tooth pastes are containing abrasives. However, most abrasives used today are being artificial or manufactured to desired characteristics for different purposes in consistent quality. They are necessities for other industries like constructions, automobiles, machinery, furniture, leather industries, etc. There are some different kinds of manufactured abrasives and most are existed as inorganic compounds. Among these, the most important abrasives is fused alumina in considering the cost against performance. Due to the great demand in many industry sectors, we even foresee fused alumina cannot be replaced within some hundreds of years.