Aluminum oxide (Al2O3) occurs naturally in the mineral corundum, which in gem-quality form is known as the precious stones ruby and sapphire. Ruby and sapphire are known for their chemical inertness and hardness. Al2O3 is produced in large quantities from the mineral bauxite. In the Bayer process, bauxite (primarily aluminum hydroxide mixed with iron hydroxide and other impurities) is selectively leached with caustic soda. Purified aluminum hydroxide is formed as a precipitate. This material is converted to aluminum oxide powder,
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which is used in the manufacture of aluminum-oxidebased ceramics. Aluminum oxide powder is used in the manufacture of porcelain, alumina laboratory ware, crucibles and metal casting molds, high temperature cements, wear-resistant parts (sleeves, tiles, seals), sandblast nozzles, etc.
Science EncyclopediaScience & Philosophy: Categorical judgement to ChimaeraCeramics - Traditional Ceramics, Glass, Aluminum Oxide, Silicon Carbide, Silicon Nitride, Processing, Forming Processes - Hydraulic cement, Modern ceramics, Magnesium oxide, Sintering, Machining