| Aluminium Oxide |
Article Index for Aluminium |
Shopping Aluminium |
Articles about Aluminium Oxide |
Website Links For Aluminium |
Information AboutAluminium Oxide |
| CATEGORIES ABOUT ALUMINIUM OXIDE | |
| aluminium compounds | |
| oxides | |
| refractory materials | |
| inorganic compounds | |
|
Aluminium oxide or '''aluminum oxide''' is a Chemical Compound of Aluminium and Oxygen with the Chemical Formula 23. It is also commonly referred to as '''alumina''' in the Mining , Ceramic , and Materials Science communities. Aluminium oxide is generally available in two concentrations: 99.5% and 96%. Aluminium oxide is responsible for metallic aluminium's resistance to Weathering . Metallic aluminium is very reactive with atmospheric Oxygen , and a thin Passivation Layer of aluminium oxide quickly forms on any exposed aluminium surface. This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called Anodising . A number of Alloys , such as Aluminium Bronze s, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. Aluminium oxide is an excellent thermal and electrical Insulator . In its crystalline form, called Corundum , its hardness makes it suitable for use as an Abrasive and as a component in Cutting Tool s. Powdered aluminium oxide is frequently used as a medium for Chromatography . Corundum is the naturally occurring Mineral form of aluminium oxide. Rubies and Sapphires are gem-quality forms of corundum with their characteristic colors due to trace impurities in the corundum structure. In 1961, GE developed "Lucalox", a transparent alumina used in Sodium Vapor Lamp s. In August 2004 , scientists in the United States working for 3M developed a technique for making an Alloy of aluminium oxide and Rare Earth Element s to produce a strong Glass called Transparent Alumina . Aluminium oxide was taken off the EPA 's chemicals lists in 1988 . INDUSTRIAL FABRICATION PROCESS Aluminium Oxide is the main component of Bauxite , the principal Ore of Aluminium . Industrially, bauxite is purified to aluminium oxide via the Bayer Process , and then converted to aluminium metal in the Hall-Heroult Process . The bauxite ore is made up of impure Al2O3 + Fe2O3 + SiO2. This is then purified by the Bayer Process: Al2O3 + 3H2O + 2NaOH --(heated) In applications like Chromatography alumina is available as so-called Brockmann types neutral, basic ( PH 9.5) and acidic (pH 4.5 when in water). EXTERNAL LINKS
|
|
|