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CAS NUMBER: 1344-28-1
EC NUMBER: 215-691-6
MOLECULAR FORMULA: Al2O3
MOLECULAR WEIGHT: 101.96
Aluminum oxide in its various levels of purity is used more often than any other advanced ceramic material.
Aluminum oxide is very good electrical insulation (1x1014 to 1x1015 Ωcm)
Aluminum oxide moderates to extremely high mechanical strength (300 to 630 MPa)
Aluminum oxide is very high compressive strength (2,000 to 4,000 MPa)
Aluminum oxide has high hardness (15 to 19 GPa)
Aluminum oxide moderates thermal conductivity (20 to 30 W/mK)
Aluminum oxide has high corrosion and wear resistance
Aluminum oxide is good gliding properties
Aluminum oxide has low density (3.75 to 3.95 g/cm3)
Aluminum oxide has operating temperature without mechanical load 1,000 to 1,500°C.
Aluminum oxide is bioinert and food compatible
Aluminium oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3.
Aluminum oxide is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium(III) oxide.
Aluminum oxide is commonly called alumina and may also be called aloxide, aloxite, or alundum depending on particular forms or applications.
Aluminum oxide occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire.
Aluminum oxide is significant in its use to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.
Aluminum oxide is one of most used raw material in the world.
Aluminum oxide can be provided with different grain sizes and purity.
Aluminum oxide is mostly used in ceramic, frit, glass, refractory and abrasive sectors.
Aluminum oxide improves the chemical stability, refractoriness, thermal shock resistance, wear resistance at the places where it is used.
Resistance to oxidative and reductive atmospheres is high.
Aluminum oxide is an inert, odourless, white amorphous material often used in industrial ceramics.
Due to its outstanding properties, Aluminum oxide has contributed to a significant number of life-extending and society-enhancing applications.
Aluminum oxide is widely used in the medical field and modern warfare.
Aluminium oxide is a thermally unstable and insoluble compound that occurs naturally in various minerals such as corundum, a crystalline variant of the oxide, and bauxite, which is considered as its principal aluminium ore.
Due to Aluminum oxides excellent mechanical, chemical and thermal qualities, alumina stands out from many comparable materials by delivering equal or better solutions for low-cost production and manufacturing.
Aluminum oxide is a white odorless crystalline powder. Water insoluble.
Properties (both physical and chemical) vary according to the method of preparation; different methods give different crystalline modifications.
The variety formed at very high temperature is quite inert chemically.
Aluminum oxide has a chemical formula Al2O3.
Aluminum oxide is amphoteric in nature, and is used in various chemical, industrial and commercial applications.
Aluminum oxide is considered an indirect additive used in food contact substances by the FDA.
Aluminum oxide is a common, naturally occurring compound that’s employed in various industries, most particularly in the production of aluminum.
Aluminum oxide is used in production of industrial ceramics. Its most common crystalline form, corundum, has several gem-quality variants, as well.
Aluminium is the most naturally abundant type of metal on our planet, and it’s common in the form of aluminium oxide, or bauxite.
Aluminum oxide variety forms once aluminium is exposed to air and it forms a thin surface layer over aluminium, making it corrosion resistant.
Aluminium oxide, or alumina, is one of the most widespread technical ceramics materials used for production of various components across many industries.
Aluminum oxide, with the chemical formula Al2O3 , is an amphoteric oxide and is commonly referred to as alumina.
Aluminum oxide, emery, sapphire, amethyst, topaz, as well as many other names are reflecting its widespread occurrence in nature and industry.
Aluminum oxide is the most common naturally occurring crystalline form of aluminum oxide.
Aluminum oxides are gem-quality forms of corundum, which owe their characteristic colors to trace impurities.
Aluminum oxides are given their characteristic deep red color and their laser qualities by traces of chromium.
Aluminum oxides come in different colors given by various other impurities, such as iron and titanium.
Aluminum oxides most significant use is in the production of aluminum metal, although it is also used as an abrasive due to its hardness and as a refractory material due to its high melting point.
Aluminum oxide crystallizesin the trigonal system and occurs aswell-developed hexagonal crystals.
Aluminum oxide is colourless and transparent whenpure but the presence of other elementsgives rise to a variety ofcolours.
Aluminum oxide is a red variety containingchromium; sapphire is ablue variety containing iron andtitanium.
Aluminum oxide occurs as arock-forming mineral in both metamorphicand igneous rocks.
Aluminum oxide ischemically resistant to weatheringprocesses and so also occurs in alluvial(placer) deposits.
The second hardest mineral after diamond, Aluminum oxide is used as an abrasive.
USES OF ALUMINIUM OXIDE:
In lighting, transparent aluminium oxide is used in some sodium vapor lamps.
Aluminium oxide is also used in preparation of coating suspensions in compact fluorescent lamps.
In chemistry laboratories, aluminium oxide is a medium for chromatography, available in basic (pH 9.5), acidic (pH 4.5 when in water) and neutral formulations.
Health and medical applications include it as a material in hip replacements and birth control pills.
Aluminum oxide is used as a scintillator and dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties.
Insulation for high-temperature furnaces is often manufactured from aluminium oxide. Sometimes the insulation has varying percentages of silica depending on the temperature rating of the material.
The insulation can be made in blanket, board, brick and loose fiber forms for various application requirements.
Small pieces of aluminium oxide are often used as boiling chips in chemistry.
Aluminum oxide is also used to make spark plug insulators.
Using a plasma spray process and mixed with titania, it is coated onto the braking surface of some bicycle rims to provide abrasion and wear resistance.
Most ceramic eyes on fishing rods are circular rings made from aluminium oxide.
In Aluminum oxides finest powdered (white) form, called Diamantine, aluminium oxide is used as a superior polishing abrasive in watchmaking and clockmaking.
Aluminium oxide is also used in the coating of stanchions in the motorcross and mountainbike industry.
This coating is combined with molybdenumdisulfate to provide long term lubrication of the surface.
Most of the aluminium oxide produced is used to form aluminium metal.
Oxygen typically catalyses corrosion in reaction with the metal aluminium.
However, when bonded with oxygen to form aluminium oxide, a protective coating forms and prevents further oxidation.
Aluminum oxide adds strength and makes the material less vulnerable to deterioration.
Aluminum oxides high melting and boiling points, in addition to its excellent thermal resistive properties, make aluminium oxide desirable in the manufacture of high-temperature furnace insulations and electrical insulators.
Aluminum oxide films are also vital components in the microchip industry.
Some of Aluminum oxides other uses include spark plug insulators, micro-electric substrates and insulating heatsinks.
Aluminium oxide is a valuable element in the formation of rubies and sapphires.
Aluminum oxides crystalline form, corundum, is the base element for these precious gems. Rubies owe their deep red colour to chromium impurities while sapphires get their variant colours from traces of iron and titanium.
Since Aluminum oxide is chemically inert, Aluminum oxide is utilised as a filler in plastics, bricks, and other heavy clayware, like kilns.
Due to Aluminum oxides extreme strength and hardness, it is often used as an abrasive for sandpaper.
Aluminum oxide is also an economical substitute for industrial diamonds.
Aluminium oxides are used, as well, for the production of piping components such as elbows, tees, straight pipes, hydro cyclones, reducers, nozzles, and valves.
Other applications include the production of various machining tools, cutting tools, thermocouple sheaths, wear-resistant pump impellers, and baffle plates.
Aluminum oxide is a white or colorless oxide occurring in two forms, a-alumina and γ-alumina.
Aluminum oxide turns into a stable a form on heating. Naturally occurring alumina is called corundum or emery.
The gemstones ruby and sapphire are aluminum oxides colored by minute traces of chromium and cobalt, respectively.
The highly protective film of oxide formed on the surface of aluminum is yet another structural variation, a defective form of rock salt.
Pure aluminum oxide is obtained by dissolving bauxite ore in sodium hydroxide solution to eliminate insoluble impurities.
Seeding the solution with material from a previous batch precipitates the hydrated oxide, which on further heating gives γ-alumina at 500 to 800°C and pure a-alumina at 1150 to 1200°C.
The latter is one of the hardest materials known.
Aluminum oxide is used widely as an abrasive substance in both its natural and synthetic forms.
Aluminum oxides refractory nature makes alumina bricks an ideal material for furnace linings and high temperature cements.
Aluminum oxide occurs in phosphate rocks along with iron and other impurities in small percentages.
Aluminum oxide and iron in phosphate rock make the superphosphate moist and sticky.
The maximum acceptable Aluminum oxide and iron in the rock for farming is 3 to 4 %.
USAGE AREAS OF ALUMINIUM OXIDE:
-Ceramic Industry
-Glass Industry
-Refractor Industry
-Production of Grinding Materials
-Production of Primary Aluminium
-Production of Transparent Armor
-Production of Ceramic Cutting Tools
APPLICATION OF ALUMINIUM OXIDE:
Known as Aluminum oxide in materials science communities or alundum (in fused form) or aloxite in the mining and ceramic communities aluminium oxide finds wide use.
Annual world production of aluminium oxide in 2015 was approximately 115 million tonnes, over 90% of which is used in the manufacture of aluminium metal.
The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications.
Large tonnages of aluminium hydroxide, from which alumina is derived, are used in the manufacture of zeolites, coating titania pigments, and as a fire retardant/smoke suppressant.
Over 90% of the aluminium oxide, normally termed Smelter Grade Alumina (SGA), produced is consumed for the production of aluminium, usually by the Hall–Héroult process.
The remainder, normally called speciality alumina is used in a wide variety of applications which reflect its inertness, temperature resistance and electrical resistance.
Aluminum oxide is reactive with oxygen, which could cause corrosion to build up.
However, when aluminum bonds with oxygen to form aluminum oxide, it creates a thin coating that protects it from oxidation.
Aluminum oxide keeps the aluminum from corroding and losing strength. The thickness and other properties of the oxide layer can be changed by using the anodizing process.
Aluminum oxide is also a product of the aluminum smelting process.
-Fillers:
Being fairly chemically inert and white, aluminium oxide is a favored filler for plastics.
Aluminium oxide is a common ingredient in sunscreen and is sometimes also present in cosmetics such as blush, lipstick, and nail polish.
-Glass:
Many formulations of glass have aluminium oxide as an ingredient.
Aluminum oxide is a commonly used type of glass that often contains 5% to 10% alumina.
-Catalysis:
Aluminium oxide catalyses a variety of reactions that are useful industrially.
In Aluminum oxides largest scale application, aluminium oxide is the catalyst in the Claus process for converting hydrogen sulfide waste gases into elemental sulfur in refineries.
Aluminum oxide is also useful for dehydration of alcohols to alkenes.
Aluminium oxide serves as a catalyst support for many industrial catalysts, such as those used in hydrodesulfurization and some Ziegler–Natta polymerizations.
-Gas purification:
Aluminium oxide is widely used to remove water from gas streams.
-Abrasive:
Aluminium oxide is used for its hardness and strength.
Aluminum oxides naturally occurring form, Corundum, is a 9 on the Mohs scale of mineral hardness (just below diamond).
Aluminum oxide is widely used as an abrasive, including as a much less expensive substitute for industrial diamond.
Many types of sandpaper use aluminium oxide crystals.
In addition, Aluminum oxides low heat retention and low specific heat make it widely used in grinding operations, particularly cutoff tools.
As the powdery abrasive mineral aloxite, Aluminum oxide is a major component, along with silica, of the cue tip "chalk" used in billiards.
Aluminium oxide powder is used in some CD/DVD polishing and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste.
Aluminum oxide is also used in microdermabrasion, both in the machine process available through dermatologists and estheticians, and as a manual dermal abrasive used according to manufacturer directions.
-Paint:
Aluminium oxide flakes are used in paint for reflective decorative effects, such as in the automotive or cosmetic industries.
-Composite fiber:
Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications.
Aluminum oxide nanofibers in particular have become a research field of interest.
-Body armor:
Some body armors utilize alumina ceramic plates, usually in combination with aramid or UHMWPE backing to achieve effectiveness against most rifle threats.
Aluminum oxide ceramic armor is readily available to most civilians in jurisdictions where it is legal, but is not considered military grade.
-Abrasion protection:
Aluminium oxide can be grown as a coating on aluminium by anodizing or by plasma electrolytic oxidation.
Both the hardness and abrasion-resistant characteristics of the coating originate from the high strength of aluminium oxide, yet the porous coating layer produced with conventional direct current anodizing procedures is within a 60-70 Rockwell hardness C range which is comparable only to hardened carbon steel alloys, but considerably inferior to the hardness of natural and synthetic corundum.
Instead, with plasma electrolytic oxidation, the coating is porous only on the surface oxide layer while the lower oxide layers are much more compact than with standard DC anodizing procedures and present a higher crystallinity due to the oxide layers being remelted and densified to obtain α-Al2O3 clusters with much higher coating hardness values circa 2000 Vickers hardness.
Aluminum oxide is used to manufacture tiles which are attached inside pulverized fuel lines and flue gas ducting on coal fired power stations to protect high wear areas.
-Electrical insulation:
Aluminium oxide is an electrical insulator used as a substrate (silicon on sapphire) for integrated circuits but also as a tunnel barrier for the fabrication of superconducting devices such as single electron transistors and superconducting quantum interference devices.
PROPERTIES OF ALUMINIUM OXIDE:
Aluminum oxide is an electrical insulator but has a relatively high thermal conductivity for a ceramic material.
Aluminium oxide is insoluble in water.
In Aluminum oxides most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools.
Aluminium oxide is responsible for the resistance of metallic aluminium to weathering.
Aluminum oxide is very reactive with atmospheric oxygen, and a thin passivation layer of aluminium oxide (4 nm thickness) forms on any exposed aluminium surface in a matter of hundreds of picoseconds.
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 bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance.
The aluminium oxide generated by anodising is typically amorphous, but discharge assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline aluminium oxide in the coating, enhancing its hardness.
Aluminium oxide was taken off the United States Environmental Protection Agency's chemicals lists in 1988.
Aluminium oxide is on the EPA's Toxics Release Inventory list if it is a fibrous form.
PROPERTIES OF ALUMINIUM OXIDE:
-Melting point: 2,072 °C (3,762 °F; 2,345 K)
-Boiling point: 2,977 °C (5,391 °F; 3,250 K)
-Hardness: 15 – 19 GPa (9 on the Mohs scale)
-Electrical resistivity: 1012 – 1013 Ωm
-Mechanical strength: 300 – 630 MPa
-Thermal conductivity: 20 – 30 W/mK
-Molecular mass: 101.96 g/mol
-Density: 3.95 g/cm3
-Appearance: Solid
CHEMICAL PROPERTIES OF ALUMINIUM OXIDE:
There are many different forms of aluminum oxide, including both crystalline and non-crystalline forms.
The chemical formula for Aluminum Oxide is Al₂O₃.
Aluminum oxide’s an electrical insulator, which means it doesn’t conduct electricity, and it also has relatively high thermal conductivity.
In addition, in its crystalline form, corundum, its hardness makes it suitable as an abrasive.
The high melting point of aluminum oxide makes it a good refractory material for lining high-temperature appliances like kilns, furnaces, incinerators, reactors of various sorts, and crucibles.
CHARACTERISTICS OF ALUMINIUM OXIDE:
Aluminum Oxide is the most widely used oxide, chiefly because it is plentiful, relatively low in cost, and equal to or better than most oxides in mechanical properties.
Density can be varied over a wide range, as can purity down to about 90% alumina to meet specific application requirements.
Alumina ceramics are the hardest, strongest, and stiffest of the oxides.
Aluminum oxides are also outstanding in electrical resistivity, dielectric strength, are resistant to a wide variety of chemicals, and are unaffected by air, water vapor, and sulfurous atmospheres.
However, with a melting point of only 2039°C, they are relatively low in refractoriness, and at 1371°C retain only about 10% of room-temperature strength.
In addition to its wide use as electrical insulators and its chemical and aerospace applications, the high hardness and close dimensional tolerance capability of alumina make this ceramic suitable for such abrasion-resistant parts as textile guides, pump plungers, chute linings, discharge orifices, dies, and bearings.
OCCURENCE OF ALUMINIUM OXIDE:
Aluminum oxide is the most common naturally occurring crystalline form of aluminium oxide.
Aluminum oxides and sapphires are gem-quality forms of corundum, which owe their characteristic colours to trace impurities.
Aluminum oxides are given their characteristic deep red colour and their laser qualities by traces of chromium.
Aluminum oxides come in different colours given by various other impurities, such as iron and titanium.
An extremely rare, δ form, occurs as the mineral deltalumite.
PRODUCTION OF ALUMINIUM OXIDE:
Aluminium hydroxide minerals are the main component of bauxite, the principal ore of aluminium.
A mixture of the minerals comprise bauxite ore, including gibbsite (Al(OH)3), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH)), along with impurities of iron oxides and hydroxides, quartz and clay minerals.
The product aluminium oxide tends to be multi-phase, i.e., consisting of several phases of aluminium oxide rather than solely corundum.
The production process can therefore be optimized to produce a tailored product.
The type of phases present affects, for example, the solubility and pore structure of the aluminium oxide product which, in turn, affects the cost of aluminium production and pollution control.
SYNONYM:
1344-28-1
gamma-Alumina
UNII-LMI26O6933
dialuminum;oxygen(2-)
MFCD00003424
LMI26O6933
Fasertonerde
Abramant
Abramax
Abrarex
Abrasit
Aloxite
Alundum
Compalox
Conopal
Faserton
