Brown aluminium oxide is fused in an electrical furnace by hig temperature. Its main raw materials are bauxite, anthracite. It dispaly brown.Its chemical composition contains Al2O3, a small amount of SiO2、TiO2、and Fe2O3, etc. The microhardness is 1800 -2200 kg/mm2, Thetoughness is higher than silicon carbide. Abrasive articles made of it are suited forgrinding metals of highten sile strength such as steel,annealed malleableiron and hard high - class refractory products. The degree of refractory is up to 1850⁰C.