What's the Composition of Brown Fused Alumina/ Brown Aluminum Oxide
Brown corundum is a kind of high-grade synthesis raw materials, belongs to alumina series. Made of high-quality bauxite, coke, iron and other auxiliary materials. These materials are refined in the arc furnace at high temperature. Corundum is a kind of high quality abrasive material which make it is widely used in sand blasting, rust removal, optics, electronics, building materials, refractory industry, mechanical processing, instrumentation, printing, grinding, stone, rubber, hydrojet and polishing and cutting industries. So what is the composition of brown fused alumia? What is the effect of each component on its performance? Here, we will introduce the composition of brown fused aluminum oxide.
The main component of brown fused alumina is aluminum oxide, including iron oxide, titanium oxide, calcium oxide, sulfur dioxide and other impurities. Microscopic examination of brown fused alumina showed that it was composed of α-alumina grains and was adhered together by a small amount of glassy slag (see Fig. 2). Corundum, which satisfies typical Btechnical conditions, consists of more than 95% alpha-alumina crystals and is composed of Al2O3 solid solution containing Ti2O3. Most of the vitreous slag is composed of silica, titanium dioxide, and other trace oxides present in the electric arc furnace. These oxides form a glassy phase, which has only a low solubility in the crystal structure of the alumina grains. For brown fused alumina abrasive grain, alumina content of not less than 95%, this range means that the alumina content of less than 95.00%, non-corundum mineral composition corresponding increase, will affect the abrasive grinding performance. However, higher than 97.5% will make the toughness of corundum greatly reduced, and the color will be bad, so do not want more than 97.50% Al2O3 content. But it should be emphasized that: Al2O3 content is higher than 97.50% of the corundum block is not defective, although its toughness is reduced, but the hardness and grinding capacity is not inferior. This corundum is known as semi-brittle corundum in foreign countries, in the country known as high alumina corundum.
The titanium oxide content of brown corundum also has a great impact on its color. Therefore, the national standard on the chemical composition of brown aluminum oxide also provides the content of titanium oxide, 1.50% ~ 3.80%. If the titanium oxide is less than 1.50%, the corundum color will become gray; if the titanium oxide content exceeds 3.80%, will affect the Al2O3 content. The content of iron oxide also has a greater impact on corundum color, will make the abrasive color black. However, the national standard in all corundum abrasive chemical composition of the Fe2O3 content are not specified. The reason is: the content of iron oxide on the magnetic properties of abrasive greater than the color. GB has strictly regulated the content of magnetic substances in the magnetic content standards of abrasive , has extremely strictly limited the content of iron oxide. In fact, make indirectly requirements on the iron oxide content .