Since the 1970s, artificial abrasives have been produced in large quantities, the most important of which are silicon carbide and alumina. Silicon carbide is commonly known as carborundum. It is prepared by mixing pure silica sand and coke with a small amount of wood chips, putting it in an electric furnace, and baking it at 2,200-2,480°C for about 36 hours. Alumina, commonly known as corundum, is commonly used in the industry to heat and melt bauxite in an electric arc furnace.
The white and transparent one is used as an abrasive for heat-sensitive metals, and the black one is used to process castings and steel. Synthetic diamond grinding wheel is the hardest abrasive tool, necessary for the sharpening of cemented carbide tools. Synthetic diamonds can also be made into tools of various shapes and sizes, which are suitable for cutting glass and ceramics. The hardness of boron carbide is higher than that of silicon carbide, so it is not suitable for making grinding wheels. It can be used to replace expensive diamond when polishing hard materials. The hardness of cubic boron carbide is twice that of silicon carbide and 2.5 times that of alumina. It is very effective for grinding certain tool steels.