... composition for AL2O3, TiO2 ring contains a small amount of SiO2 and Fe2O3, microhardness HV1800-2200, toughness than SiC high ... alkali solution heat slightly reaction oxidation reduction effect: no density: 3.90 g/cm3 hardness: knoop spectrum hardness 2000 ... The sand brown corundum - sandblasting abrasive hardness modest, stacking density high, no free silica, more than major, good toughness, ...