Corundum has many colors as it contains different pigment particles. According to the color of corundum, it can be divided into Brown fused alumina, white fused alumina, black fused alumina, pink fused alumina, zirconia fused alumina, etc. They are all belong to artificial abrasives and widely used for abrasive industry.

Brown fused alumina appearance is brown, it’s main chemical composition is A12O3 with about 95%. It has the characteristic of high hardness, toughness, sharp grain and the price is quite cheap. It is suitable for grinding high tensile strength metal, generally can be replaced by it in the case of lack of other abrasives. It’s widely used in the coarse grinding of ordinary steel, such as carbon steel, alloy steel, commonly can be used for calcined cast iron, hard bronze, etc. Brown fused alumina also can be used for grinding wheel, resin grinding wheel cutting, sand tile, abrasive cloth, abrasive paper and so on.

The hardness of white fused alumina(white corundum) is slightly higher than brown fused alumina, but it’s toughness is a bit poor as easily to cut into workpieces when grinding. The price of white fused alumina is higher than that of brown fused alumina since good sharpness,less heat, strong capability of grinding. Suitable for grinding high hardness of steel, such as high speed steel, high carbon steel, hardened steel, alloy steel, etc.

Pink fused alumina (Chromium corundum), as the derived varieties of white corundum， it’s smelting process is the same as the white corundum, just add a certain amount of chrome oxide in smelting process into a light purple or rose color. Pink fused alumina’s hardness close to white corundum, toughness slightly higher than the white corundum with high strength, good grinding performance, high grinding accuracy. Abrasive tools are made of this abrasives with good shape. The application scope is similar to white corundum, especially suitable for all kinds of cutting tools, measuring tools and instrument parts of fine grinding and molding grinding. Pink fused alumina usually has better grinding performance than white fused alumina.

Zirconia fused alumina is the eutectic compound of α-A12O3 and A12O3 - ZrO2, it has the characteristic of slightly lower hardness but strong toughness, high strength, usually with a finer crystal size and wear-resisting performance is good. Zirconia fused alumina is suitable for high speed heavy load grinding, snagging cast iron, cast steel, alloy steel and high speed steel, etc., especially suitable for titanium alloy, heat-resistant alloy, high vanadium steel, stainless steel grinding.

The smelting method of black fused alumina is the same as the brown fused alumina. It is made of bauxite as raw material and a small amount of reducing agent in the process of smelting. It’s power consumption is about two-thirds of the brown fused alumina.It belongs to the derived varieties of brown fused alumina with black color. Black fused alumina has relatively low hardness but good toughness as it’s low content of Al2O and have a certain amount of Fe2O3 (about10%). It can be used for grinding, such as polishing or coarse grinding before products electroplating, also used for producing coated abrasive tools, resin cutting disc, polishing block, etc.