| Identification | More | [Name]
Aluminum oxide | [CAS]
1344-28-1 | [Synonyms]
ACTIVATED ALUMINA, WEAKLY ACIDIC
ALCOA NO CG20
ALPHA-ALUMINA
ALPHA-ALUMINUM (III) OXIDE
ALUMINA
ALUMINA A
ALUMINA A 18-32
ALUMINA, ACID, BROCKMAN ACTIVITY I
ALUMINA, ACTIVATED
ALUMINA ACTIVATED 200
ALUMINA ACTIVATED 300
ALUMINA, ACTIVATED, ACIDIC, BROCKMANN I
ALUMINA, ACTIVATED, BASIC
ALUMINA, ACTIVATED, BASIC, BROCKMANN I
ALUMINA, ACTIVATED, NEUTRAL, BROCKMANN I
ALUMINA, ADSORPTION
ALUMINA A-TLC
ALUMINA B
ALUMINA B-0
ALUMINA B-10 | [EINECS(EC#)]
215-691-6 | [Molecular Formula]
Al2O3 | [MDL Number]
MFCD00003424 | [Molecular Weight]
101.96 | [MOL File]
1344-28-1.mol |
| Chemical Properties | Back Directory | [Definition]
The mineral corundum
is natural aluminum oxide, and emery, ruby, and
sapphire are impure crystalline varieties. The mixed
mineral bauxite is a hydrated aluminum oxide.
| [Appearance]
Aluminum is a combustible, light, silverywhite, soft, ductile, malleable, amphoteric metal | [Melting point ]
2040 °C(lit.)
| [Boiling point ]
2980°C | [density ]
3.97 | [vapor pressure ]
17 mm Hg ( 20 °C)
| [refractive index ]
1.765 | [Fp ]
2980°C | [storage temp. ]
Sealed in dry,Room Temperature | [solubility ]
Miscible with ethanol. | [form ]
powder
| [color ]
White to pink | [Specific Gravity]
3.97 | [Odor]
Odorless | [PH]
7.0±0.5 ( in H2O) | [PH Range]
3.5 - 4.5 | [Water Solubility ]
INSOLUBLE | [Crystal Structure]
Trigonal | [Merck ]
14,356 | [Dielectric constant]
4.5（Ambient） | [Exposure limits]
ACGIH: TWA 1 mg/m3
OSHA: TWA 15 mg/m3; TWA 5 mg/m3 | [InChIKey]
PNEYBMLMFCGWSK-UHFFFAOYSA-N | [CAS DataBase Reference]
1344-28-1(CAS DataBase Reference) | [NIST Chemistry Reference]
Aluminum oxide(1344-28-1) | [EPA Substance Registry System]
1344-28-1(EPA Substance) |
| Questions And Answer | Back Directory | [Description]
The oxide of aluminum is Al2O3. The natural crystalline mineral is called corundum, but the synthetic crystals used for abrasives are designated usually as aluminum oxide or marketed under trade names. For other uses and as a powder, it is generally called alumina. It is widely distributed in nature in combination with silica and other minerals and is an important constituent of the clays for making porcelain, bricks, pottery, and refractories.
The crushed and graded crystals of alumina when pure are nearly colorless, but the fine powder is white. Off colors are due to impurities. American aluminum oxide used for abrasives is at least 99.5% pure, in nearly colorless crystals melting at 2050°C. The chief uses for alumina are for the production of aluminum metal and for abrasives, but it is also used for ceramics, refractories, pigments, catalyst carriers, and in chemicals.
Aluminum oxide crystals are normally hexagonal and are minute in size. For abrasives, the grain sizes are usually from 100 to 600 mesh. The larger grain sizes are made up of many crystals, unlike the single-crystal large grains of SiC. The specific gravity is about 3.95, and a hardness is up to 2000 Knoop.
There are two kinds of ultrafine alumina abrasive powder. Type A is alpha alumina with hexagonal crystals with particle size of 0.3 μm, density 4.0, and hardness 9 Mohs, and type B is gamma alumina with cubic crystals with particle size under 0.1 μm, specific gravity of 3.6, and a hardness 8. Type A cuts faster, but type B gives a finer finish. At high temperatures, gamma alumina transforms to the alpha crystal. The aluminum oxide most frequently used for refractories is the beta alumina and hexagonal crystals heat-stabilized with sodium.
Activated alumina is partly dehydrated alumina trihydrate, which has a strong affinity for moisture or gases and is used for dehydrating organic solvents, and hydrated alumina is alumina trihydrate. | [History]
The hexagonally closest packed α-Al2O3 modification is the only stable oxide in the Al2O3 –H2O system. Corundum is a common mineral in igneous and metamorphic rocks. Red and blue varieties of gem quality are called ruby and sapphire, respectively. The lattice of corundum is composed of hexagonally closest packed oxygen ions forming layers parallel to the (0001) plane. Only two-thirds of the octahedral interstices are occupied by aluminum ions. The structure may be described roughly as consisting of alternating layers of Al and O ions. The corundum structurewas determined in the early 1920s . | [Physical properties]
Regular aluminum oxide is white and has a chemical composition of approximately 95 % Al2O3, 1.5 % SiO2, less than 0.5 % Fe2O3, and 3 % TiO2. Because of very slow cooling in the Higgins furnace, the crystals of alumina are coarse, averaging 10 – 15mm in diameter. | [Classifications]
Four grades can be distinguished according to the content of calcined aluminium:
(i) Standard calcined aluminas with a sodium content of between 3000 and 7000 ppm wt.
Na2O.
(ii) Intermediate calcined alumina with a sodium content of between 1000 and 3000 ppm wt.
Na2O. The sodium content of this grade has been lowered by modifying the conditions
of the precipitation of gibbsite or of the calcination.
(iii) Low-sodium calcined aluminas with a sodium content of between 300 and 1000 ppm wt.
Na2O. These aluminas are usually obtained by washing the precursor or by the extraction of sodium as a volatile compound with the mineralizer during calcination.
(iv) High-purity aluminas with an extra-low sodium content below 100 ppm wt. Na2O.
These aluminas obtained from an aluminum hydroxide produced by a process other
than the Bayer process. The main applications for calcined aluminas are as feedstocks
for refractories, glass and enamel, tiles and porcelain, and advanced ceramics. The diversity of applications for calcined aluminas can be explained by the wide range of
properties: refractoriness, sinterability, chemical inertness in both oxidizing and reducing atmosphere and in both acid and alkaline media, hardness, wear and abrasion
resistance, dimensional stability, high thermal conductivity, electrical resistivity, low
dielectric loss and high permittivity, and high ionic conductivity in the case of beta-alumina. | [Uses]
Aluminum Oxide (Alumina) 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. They are also outstanding and with electrical resistivity and 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. | [Industrial Manufacture]
Monocrystalline aluminum oxide is a very high purity abrasive, produced directly from bauxite in a single-stage fusion . The preferred method employs a furnace feed consisting of bauxite, pyrite (FeS2) or sulfur, carbon, and iron borings. When subjected to fusion in the Higgins batch furnace, two immiscible liquids are formed as with regular aluminum oxide. However, in the present case very slowcooling of the upper liquid results in essentially pure, individual crystals of Al2O3 in a matrix of sulfides. After the pig has cooled and been crushed, the matrix is removed chemically and mechanically. This treatment releases alumina crystals in the range of sizes required by the industry. |
| Safety Data | Back Directory | [Hazard Codes ]
Xi,F | [Risk Statements ]
R36/37/38:Irritating to eyes, respiratory system and skin .
R67:Vapors may cause drowsiness and dizziness.
R36/38:Irritating to eyes and skin .
R11:Highly Flammable. | [Safety Statements ]
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S24/25:Avoid contact with skin and eyes .
S16:Keep away from sources of ignition-No smoking .
S7:Keep container tightly closed .
S36:Wear suitable protective clothing . | [WGK Germany ]
-
| [RTECS ]
BD1200000
| [F ]
3 | [TSCA ]
Yes | [HazardClass ]
8 | [HS Code ]
28181010 | [Safety Profile]
Suspected carcinogen with experimental neoplastigenic and tumorigenic data by implantation. Inhalation of finely divided particles may cause lung damage (Shaver's disease). Exothermic reaction above 200℃ with halocarbon vapors produces toxic HCl and phosgene. See also ALUMINUM COMPOUNDS | [Hazardous Substances Data]
1344-28-1(Hazardous Substances Data) |
| Hazard Information | Back Directory | [General Description]
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. | [Reactivity Profile]
ALUMINUM OXIDE(1344-28-1) is chemically amphoteric (behaves as a weak acid in the presence of base and as a weak base in the presence of acid). May act catalytically. May cause the exothermic polymerization of ethylene oxide. May cause the vigorous polymerization of vinyl chloride [MCA SD-75, 1970]. The degree of subdivision of the ALUMINUM OXIDE(1344-28-1) may affect the vigor of such reactions. | [Air & Water Reactions]
Insoluble in water. | [Hazard]
Toxic by inhalation of dust. Confirmed car-
cinogen.
| [Potential Exposure]
Most hazardous exposures to aluminum occur in smelting and refining processes. Aluminum is mostly produced by electrolysis of Al2O3 dissolved in molten cryolite (Na3AlF6). Aluminum is alloyed with copper, zinc, silicon, magnesium, manganese, and nickel; special additives may include chromium, lead, bismuth, titanium, zirconium, and vanadium. Aluminum and its alloys can be extruded or processed in rolling mills, wire works, forges, or foundries; and are used in the shipbuilding, electrical, building, aircraft, automobile, light engineering, and jewelry industries. Aluminum foil is widely used in packaging. Powdered aluminum is used in the paints and pyrotechnic industries. Alumina, emery, and corundum has been used for abrasives, refractories, and catalysts; and in the past in the first firing of china and pottery. | [First aid]
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. | [Shipping]
UN1309 Aluminum powder, coated, Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN1383 Pyrophoric metals, n.o.s. or Pyrophoric alloys, n.o.s., Hazard Class: 4.2; Labels: 4.2-Spontaneously combustible material, Technical Name Required. UN1396 Aluminum powder, uncoated, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material. NA9260 (North America) Aluminum, molten, Hazard class: 9; Labels: 9-Miscellaneous hazardous material. | [Incompatibilities]
Aluminum powder forms an explosive mixture with air and is a strong reducing agent that reacts violently with oxidizers, strong bases; strong acids; somehalogenated hydrocarbons; nitrates, sulfates, metal oxides and many other substances. Keep away from combustible materials.
| [Chemical Properties]
Aluminum is a combustible, light, silverywhite, soft, ductile, malleable, amphoteric metal.Vary according to the method of preparation. White powder, balls, or lumps of various mesh.Insoluble in water, dif- ficultly soluble in mineral acids and strong alkali. Noncombustible. | [Chemical Properties]
Aluminum oxide occurs as a white crystalline powder. Aluminum
oxide occurs as two crystalline forms: α-aluminum oxide is
composed of colorless hexagonal crystals, and γ-aluminum oxide
is composed of minute colorless cubic crystals that are transformed
to the α-form at high temperatures. | [Waste Disposal]
Consult with environmental regulatory agencies for guidance on acceptable disposalpractices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal of Aluminum Oxide-Disposal in a sanitary landfill. Mixing of industrial process wastes and municipal wastes at such sites is not encouraged however. Aluminum powder may be recovered and sold as scrap. Recycling and recovery is a viable option to disposal for aluminum metal and aluminum fluoride (A-57).
| [Occurrence]
Occurs in nature in abundance; the principal forms are bauxites and laterites. The mineral corundum is used to produce precious gems, such as ruby and sapphire. Activated aluminas are used extensively as adsorbents because of their affinity for water and other polar molecules; and as catalysts because of their large surface area and appropriate pore sturcture. As adsorbents, they are used for drying gases and liquids; and in adsorption chromatography. Catalytic properties may be attributed to the presence of surface active sites (primarily OH- , O2- , and Al3+ ions). Such catalytic applications include sulfur recovery from H2S (Clauss catalysis); dehydration of alcohols, isomerization of olefins; and as a catalyst support in petroleum refining. | [Characteristics]
Aluminum Oxide (Alumina) 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. They 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. | [Production Methods]
The Bayer process begins by grinding the bauxite and mixing it with sodium hydroxide in a digester. The sodium hydroxide dissolves aluminum oxide components to produce aluminum hydroxide compounds. For gibbsite, the reaction is: Al(OH)3 + NaOH → Al(OH)4- + Na+. Insoluble impurities such as silicates, titanium oxides, and iron oxides are removed from the solution while sodium hydroxide is recovered and recycled. Reaction conditions are then modified so that aluminum trihydroxide (Al(OH)3) precipitates out. The reaction can be represented as the reverse of the previous reaction: Al(OH)4- + Na+ → Al(OH)3 + NaOH. Aluminum trihydroxide is calcined to drive off water to produce alumina:
Al(OH)3 Al2O3 + 3H2O. | [Health Hazard]
The aluminas are considered to
be nuisance dusts; their role in fibrogenic lung
disease remains unclear.
Assessment of the toxicity of aluminas has
been complicated by the chemical and physical
variants of the compounds and inconsistencies
in the nomenclature used to describe them.1
The group of compounds referred to as aluminas
is composed of various structural forms of
aluminum oxide, trihydroxide, and oxyhydroxide.
2 As these aluminas are heated, dehydration
occurs, producing a variety of transitional
forms; temperatures between 200 and 500°C
result in low-temperature-range transitional aluminas characterized by increased catalytic
activity and larger surface area.(Transitional
aluminas include c, h, and g forms, which,
taken together, were formerly termed “g.”) | [Flammability and Explosibility]
Notclassified | [Pharmaceutical Applications]
Aluminum oxide is used mainly in tablet formulations.It is used
for decoloring powders and is particularly widely used in antibiotic
formulations. It is also used in suppositories, pessaries, and urethral
inserts. Hydrated aluminum oxide is used in
mordant dyeing to make lake pigments, in cosmetics, and
therapeutically as an antacid. | [Industrial uses]
Fused aluminum oxide was the second synthetic abrasive to be developed. Synthetic aluminum oxide (alumina) is made as a white powder and can be somewhat harder than corundum (natural alumina) because of its purity. However, corundum has a Mohs hardness of approximately 9 (on a scale of 1 to 10. Alumina can be processed with different properties by slight alteration of the reactants in the manufacturing process. Several grain sizes of alumina are available, and alumina has largely replaced emery for several abrasive uses. Aluminum oxide is widely used to make bonded abrasives, coated abrasives, and air-propelled grit abrasives for dental applications.
Sintered aluminum oxide is used to make white stones, which are popular for adjusting dental enamel and finishing metal alloys, resin-based composites, and ceramic materials.
Pink and ruby variations of aluminum oxide abrasives are made by adding chromium compounds to the original melt. These variations are sold in a vitreous-bonded form as noncontaminating mounted stones for the preparation of metal– ceramic alloys to receive porcelain. Remnants of these abrasives and other debris should be removed from the surface of metals used for metal–ceramic bonding so as not to prevent optimal bonding of porcelain to the metal alloy. A review by Yamamoto (see Selected Reading) suggests that carbide burs are the most effective instruments for finishing this type of alloy because they do not contaminate the metal surface with entrapped abrasive particles. | [Safety]
Aluminum oxide is generally regarded as relatively nontoxic and nonirritant when used as an excipient. Inhalation of finely divided particles may cause lung damage (Shaver's disease).
HUMAN HEALTH RISK ASSESSMENT FOR ALUMINIUM, ALUMINIUM OXIDE, AND ALUMINIUM HYDROXIDE | [storage]
Aluminum oxide should be stored in a well-closed container in a
cool, dry, place. It is very hygroscopic. | [Purification Methods]
Stir the oxide with hot 2M HNO3, either on a steam bath for 12hours (changing the acid every hour) or three times for 30minutes, then wash it with hot distilled water until the washings have pH 4, and follow by three washings with hot MeOH. The product is dried at 270o [Angyal & Young J Am Chem Soc 81 5251 1959]. For the preparation of alumina for chromatography see Chapter 1. [For , and Al2O3 see Becher in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 822-823 1963 and Wagner in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1662 1965.] | [Regulatory Status]
Included in the FDA Inactive Ingredients Database (oral tablets and
topical sponge). Included in nonparenteral medicines licensed in the
UK. |
| Questions and Answers (Q&A) | Back Directory | [Toxicity]
Chronic inhalation of Al2O3 dusts may cause lung damage.
| [Reactions]
Aluminum oxide exhibits amphoteric behavior. It is soluble both in acids and bases. With acids, it produces their corresponding salts. It froms Al2(SO4)3, Al(NO3)3 and AlCl3 upon reactions with H2SO4, HNO3, and HCl, respectively. In acid medium, it exists as a solvated aluminum ion, in which water molecules are hexacoordinated to trivalent Al3+, as shown below:
Al2O3 + 6H3O+ + 3H2O ——› 2[Al(H2O)6]3+
(Rollinson, C. L., 1978., Aluminum Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed. Vol 2, pp 188-97. NY,: Wiley Interscience)
Aluminum oxide forms hydroxide in aqueous alkaline solution. The reaction is slow. The products, aluminum hydroxides (hydrated aluminas), contain hexacoordinated aluminohydroxide anion:
Al2O3 + 2OH– + 7H2O → 2[Al(OH)4(H2O)2]–
In its dry state, Aluminum oxide exhibiting basicity reacts with silica, forming aluminum silicate
Al2O3 + 3SiO2 → Al2(SiO3)3
Similarly, with basic CaO or MgO aluminate salts are formed
MgO + Al2O3 → Mg(AlO2)2 CaO + Al2O3 → Ca(AlO2)2
It forms aluminum nitride, AlN when heated with coal in a stream of nitrogen; and aluminum borate, Al2O3 •B2O3 when heated with B2O3 at 1000°C.
| [Preparation]
Pure Aluminum oxide, needed to produce aluminum by the Hall process, is made by the Bayer process. The starting material is bauxite (Al2O3 • nH2O). The ore contains impurities, such as, SiO2, Fe2O3, TiO2, and Na2O. Most impurities are removed following treatment with caustic soda solution. Bauxite is dissolved in NaOH solution. Silica, iron oxides and other impurities are filtered out of the solution. CO2 is then bubbled through this solution. This precipitates out hydrated Aluminum oxide, which is heated to remove water and produce Al2O3. These impurities are removed. Calcinations of bauxite produce Aluminum oxide of abrasive and refractory grades. Activated Aluminum oxides of amorphous type, as well as the transition Aluminum oxides of γ, η, χ, and ρ forms, are obtained from various aluminum hydroxides, such as, α- and β-trihydrates, α-monohydrate and alumina gel. Such chemicals are obtained from bauxite by the Bayer process also.
| [Physical properties]
Al2O3 Colorless hexagonal crystal; refractive index 1.768; density 3.965 g/cm3 (at 25°C); mp 2072°C; bp 2980°C; insoluble in water
α-Al2O3 Colorless rhombic crystal; mp between 2005 to 2025°C ; density 4.022 g/m3 ; hardness 9Moh
γ-Al2O3 white microscopic crystal
Al2O3•H2O colorless rhombic crystal; refractive index 1.624; density 3.014 g/cm3
Al2O3•3H2O white monoclinic crystal; refractive index 1.577; density 2.420 g/cm3
All forms are insoluble in water.
| [Uses]
Occurs in nature in abundance; the principal forms are bauxites and laterites. The mineral corundum is used to produce precious gems, such as ruby and sapphire. Activated aluminas are used extensively as adsorbents because of their affinity for water and other polar molecules; and as catalysts because of their large surface area and appropriate pore sturcture. As adsorbents, they are used for drying gases and liquids; and in adsorption chromatography. Catalytic properties may be attributed to the presence of surface active sites (primarily OH– , O2– , and Al3+ ions). Such catalytic applications include sulfur recovery from H2S (Clauss catalysis); dehydration of alcohols, isomerization of olefins; and as a catalyst support in petroleum refining.
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