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Both white and brown corundum contain alumina
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【概要描述】White corundum is made from high-quality aluminum oxide powder, which is refined and crystallized by electric melting. It has high purity, good self sharpening, acid and alkali corrosion resistance, high temperature resistance, and stable thermal performance. White alumina has slightly higher hardness than brown alumina, slightly lower toughness, high purity, good self sharpening, strong grinding ability, low heat generation, high efficiency, acid alkali corrosion resistance, and good high-temperature thermal stability. Made of white corundum grit sand, it is suitable for grinding fine-grained abrasives such as high carbon steel, high-speed steel, and stainless steel. White corundum can also be used for precision casting and advanced refractory materials.
White corundum is made from high-quality aluminum oxide powder, which is refined and crystallized by electric melting. It has high purity, good self sharpening, acid and alkali corrosion resistance, high temperature resistance, and stable thermal performance. White alumina has slightly higher hardness than brown alumina, slightly lower toughness, high purity, good self sharpening, strong grinding ability, low heat generation, high efficiency, acid alkali corrosion resistance, and good high-temperature thermal stability. Made of white corundum grit sand, it is suitable for grinding fine-grained abrasives such as high carbon steel, high-speed steel, and stainless steel. White corundum can also be used for precision casting and advanced refractory materials.
Both white and brown corundum contain alumina, with a alumina content of over 99% for white corundum and over 95% for brown corundum. Due to their high alumina content, white corundum is white in color, while brown corundum is brownish black. In production, white corundum is produced using aluminum oxide powder (similar to the raw material used for electrolytic aluminum), while brown corundum is produced using calcined bauxite.
It is necessary to have a simple understanding of the physical structure of brown alumina, in order to avoid unexpected quality issues. Microscopic examination of brown corundum indicates that it is composed of α- It is composed of alumina grains and is adhered together by a small amount of glassy slag (see Figure 2). Brown alumina that meets typical technical conditions, consisting of over 95% α- Aluminum oxide crystals are composed of Al2O3 solid solutions containing Ti2O3. The vast majority of glassy slag is composed of silicon dioxide, titanium dioxide, and other trace oxides present in electric arc furnaces. These oxides form the glass phase, which α- The crystal structure of alumina grains only has low solubility. The amount of glassy slag and its relationship with α- The distribution of impurities between alumina grains is the main factor affecting the properties of brown alumina. Α- Aluminum oxide endows brown corundum materials with hardness and high melting point, while the presence of glass phase and impurities endows brown corundum with toughness or resistance to fragmentation. For brown corundum that meets typical technical requirements, the mixing ratio of silica and titanium dioxide in the glass phase is theoretically close to 1:1. If there is too much silica in the phase, the excess silica cannot be retained in the glass phase, but reacts with a portion of alumina to form mullite (2SiO2 (3Al2O3)), which will reduce the toughness of brown corundum.
White corundum is made from industrial aluminum oxide powder, which is melted at a high temperature of over 2000 degrees in an electric arc and cooled. It is crushed, magnetically separated to remove iron, and sieved into various particle sizes. Its texture is dense, its hardness is high, and the particles form sharp corners. Suitable for manufacturing ceramics, resin bonded abrasives, as well as grinding, polishing, sandblasting, precision casting, etc. It can also be used to manufacture advanced refractory materials.
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