Aluminum And Iron Iii Oxide

Chemic chemical compound with formula Al2O3

This article is about aluminium(III) oxide, Al₂O_iii. For other uses, see Aluminium oxides.

Aluminium oxide
(Aluminum oxide)

Identifiers
CAS Number	1344-28-one Y
3D model (JSmol)	Interactive image Interactive paradigm
ChEMBL	ChEMBL3707210
ChemSpider	8164808 Y
DrugBank	DB11342
ECHA InfoCard	100.014.265
EC Number	215-691-6
PubChem CID	9989226
RTECS number	BD120000
UNII	LMI26O6933 Y
CompTox Dashboard (EPA)	DTXSID1052791
InChI InChI=1S/2Al.3O/q2*+three;3*-2 Y Fundamental: PNEYBMLMFCGWSK-UHFFFAOYSA-Northward Y InChI=one/2Al.3O/q2*+iii;iii*-2 Key: PNEYBMLMFCGWSK-UHFFFAOYAC
SMILES [Al+3].[Al+3].[O-two].[O-2].[O-2] [O-2].[O-2].[O-ii].[Al+three].[Al+3]
Backdrop
Chemical formula	Al 2 O 3
Molar mass	101.960 one thousand·mol−one
Appearance	white solid
Odor	odorless
Density	3.987g/cmthree
Melting betoken	2,072 °C (iii,762 °F; ii,345 M)[3]
Humid point	ii,977 °C (v,391 °F; three,250 Chiliad)[4]
Solubility in h2o	insoluble
Solubility	insoluble in all solvents
log P	0.31860[ane]
Magnetic susceptibility (χ)	−37.0×10−6 cm3/mol
Thermal conductivity	xxx W·m−1·K−1 [ii]
Refractive index (n D)	due northω=i.768–one.772 nε=1.760–1.763 Birefringence 0.008
Construction
Crystal structure	Trigonal, hR30
Space group	R3c (No. 167)
Lattice constant	a = 478.5 pm, c = 1299.one pm
Coordination geometry	octahedral
Thermochemistry
Std molar entropy (South ⦵ 298)	50.92 J·mol−i·K−ane [5]
Std enthalpy of formation (Δf H ⦵ 298)	−1675.seven kJ/mol[v]
Pharmacology
ATC code	D10AX04 (WHO)
Hazards
GHS labelling:
Pictograms
NFPA 704 (fire diamond)	0 0 0
Wink point	Not-flammable
NIOSH (Us health exposure limits):
PEL (Permissible)	OSHA fifteen mg/m3 (Full Grit) OSHA 5 mg/thousand3 (Respirable Fraction) ACGIH/TLV x mg/one thousand3
REL (Recommended)	none[vi]
IDLH (Firsthand danger)	Due north.D.[6]
Related compounds
Other anions	aluminium hydroxide aluminium sulfide aluminium selenide
Other cations	boron trioxide gallium oxide indium oxide thallium(III) oxide
Supplementary data page
Aluminium oxide (data folio)
Except where otherwise noted, information are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Yverify (what is Y Northward  ?) Infobox references

Chemical compound

Aluminium oxide is a chemical chemical compound of aluminium and oxygen with the chemical formula Al_twoO_iii . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium(Three) oxide. Information technology is commonly chosen alumina and may also be chosen aloxide, aloxite, or alundum depending on detail forms or applications. Information technology occurs naturally in its crystalline polymorphic phase α-Al₂O₃ as the mineral corundum, varieties of which form the precious gemstones ruby-red and sapphire. Al₂O_iii is significant in its apply to produce aluminium metal, as an annoying owing to its hardness, and as a refractory material owing to its high melting indicate.^[7]

Natural occurrence [edit]

Corundum is the most common naturally occurring crystalline form of aluminium oxide.^[8] Rubies and sapphires are gem-quality forms of corundum, which owe their feature colours to trace impurities. Rubies are given their characteristic deep crimson colour and their laser qualities by traces of chromium. Sapphires come in unlike colours given by various other impurities, such as iron and titanium. An extremely rare, δ form, occurs as the mineral deltalumite.^{[9] [10]}

Backdrop [edit]

Aluminium oxide in its powdered form

Al_iiO_three is an electrical insulator merely has a relatively loftier thermal electrical conductivity (30 Wm⁻¹K^−ane )^[2] for a ceramic textile. Aluminium oxide is insoluble in water. In its almost commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for apply as an annoying and as a component in cutting tools.^[7]

Aluminium oxide is responsible for the resistance of metallic aluminium to weathering. Metallic aluminium is very reactive with atmospheric oxygen, and a thin passivation layer of aluminium oxide (4 nm thickness) forms on whatsoever exposed aluminium surface in a affair of hundreds of picoseconds.^{[ better source needed ] [xi]} This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can exist enhanced using a procedure chosen anodising. A number of alloys, such as aluminium bronzes, exploit this holding 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 blanket, enhancing its hardness.

Aluminium oxide was taken off the United states Environmental Protection Bureau'due south chemicals lists in 1988. Aluminium oxide is on the EPA's Toxics Release Inventory list if it is a fibrous course.^[12]

Amphoteric nature [edit]

Aluminium oxide is an amphoteric substance, pregnant it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base of operations with an acid, neutralising the other and producing a salt.

Al₂O₃ + 6 HF → 2 AlF₃ + three H_iiO

Al₂O₃ + 2 NaOH + 3 H₂O → two NaAl(OH)₄ (sodium aluminate)

Structure [edit]

Corundum from Brazil, size about ii×3 cm.

The almost common form of crystalline aluminium oxide is known as corundum, which is the thermodynamically stable form.^[13] The oxygen ions form a nigh hexagonal close-packed structure with the aluminium ions filling 2-thirds of the octahedral interstices. Each Al³⁺ middle is octahedral. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a space group of R3c (number 167 in the International Tables). The archaic cell contains 2 formula units of aluminium oxide.

Aluminium oxide besides exists in other metastable phases, including the cubic γ and η phases, the monoclinic θ phase, the hexagonal χ phase, the orthorhombic κ stage and the δ phase that can exist tetragonal or orthorhombic.^{[thirteen] [14]} Each has a unique crystal structure and properties. Cubic γ-Al₂O₃ has important technical applications. The so-called β-Al₂O₃ proved to be NaAl₁₁O₁₇.^[15]

Molten aluminium oxide near the melting temperature is roughly 2/three tetrahedral (i.eastward. 2/three of the Al are surrounded by 4 oxygen neighbors), and ane/three 5-coordinated, with very piddling (<5%) octahedral Al-O present.^[16] Effectually 80% of the oxygen atoms are shared among 3 or more than Al-O polyhedra, and the majority of inter-polyhedral connections are corner-sharing, with the remaining 10–xx% existence edge-sharing.^[16] The breakdown of octahedra upon melting is accompanied past a relatively large volume increment (~33%), the density of the liquid close to its melting signal is 2.93 g/cm³.^[17] The structure of molten alumina is temperature dependent and the fraction of 5- and six-fold aluminium increases during cooling (and supercooling), at the expense of tetrahedral AlO_iv units, approaching the local structural arrangements found in amorphous alumina.^[18]

Production [edit]

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.^[nineteen] Bauxites are found in laterites. Bauxite is typically purified using the Bayer process:

Al_twoO₃ + H_iiO + NaOH → NaAl(OH)₄

Al(OH)₃ + NaOH → NaAl(OH)_iv

Except for SiO₂, the other components of bauxite do not dissolve in base of operations. Upon filtering the basic mixture, Fe_twoO₃ is removed. When the Bayer liquor is cooled, Al(OH)₃ precipitates, leaving the silicates in solution.

NaAl(OH)_four → NaOH + Al(OH)_three

The solid Al(OH)₃ Gibbsite is and then calcined (heated to over 1100 °C) to give aluminium oxide:^[seven]

2 Al(OH)_three → Al₂O_three + 3 H_twoO

The production aluminium oxide tends to be multi-phase, i.eastward., consisting of several phases of aluminium oxide rather than solely corundum.^[14] The production process can therefore be optimized to produce a tailored product. The blazon of phases present affects, for example, the solubility and pore structure of the aluminium oxide product which, in plow, affects the price of aluminium production and pollution control.^[fourteen]

Applications [edit]

Known equally alpha alumina in materials science communities or alundum (in fused form) or aloxite^[20] in the mining and ceramic communities aluminium oxide finds wide use. Annual globe product of aluminium oxide in 2015 was approximately 115 million tonnes, over ninety% of which is used in the manufacture of aluminium metal.^[vii] 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 industry of zeolites, blanket titania pigments, and as a fire retardant/smoke suppressant.

Over ninety% of the aluminium oxide, unremarkably termed Smelter Class Alumina (SGA), produced is consumed for the product of aluminium, usually past the Hall–Héroult procedure. The balance, normally chosen speciality alumina is used in a wide variety of applications which reflect its inertness, temperature resistance and electrical resistance.^[21]

Fillers [edit]

Existence 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 chroma, lipstick, and nail polish.

Glass [edit]

Many formulations of glass take aluminium oxide as an ingredient.^[22] Aluminosilicate glass is a normally used type of drinking glass that often contains 5% to 10% alumina.

Catalysis [edit]

Aluminium oxide catalyses a variety of reactions that are useful industrially. In its largest calibration application, aluminium oxide is the catalyst in the Claus process for converting hydrogen sulfide waste matter gases into elemental sulfur in refineries. It is likewise useful for dehydration of alcohols to alkenes.

Aluminium oxide serves every bit a goad support for many industrial catalysts, such as those used in hydrodesulfurization and some Ziegler–Natta polymerizations.

Gas purification [edit]

Aluminium oxide is widely used to remove water from gas streams.^[23]

Annoying [edit]

Aluminium oxide is used for its hardness and strength. Its naturally occurring form, corundum, is a 9 on the Mohs calibration of mineral hardness (simply below diamond). Information technology is widely used equally an abrasive, including as a much less expensive substitute for industrial diamond. Many types of sandpaper use aluminium oxide crystals. In add-on, its low heat retention and low specific heat brand information technology widely used in grinding operations, especially cutoff tools. As the powdery annoying mineral aloxite, it is a major component, along with silica, of the cue tip "chalk" used in billiards. Aluminium oxide pulverization is used in some CD/DVD polishing and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste. It is as well used in microdermabrasion, both in the auto procedure available through dermatologists and estheticians, and as a manual dermal abrasive used according to manufacturer directions.

Paint [edit]

Aluminium oxide flakes are used in paint for cogitating decorative effects, such as in the automotive or cosmetic industries.^{[ commendation needed ]}

Blended cobweb [edit]

Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications (eastward.g., Cobweb FP, Nextel 610, Nextel 720).^[24] Alumina nanofibers in particular have get a research field of interest.

Body armor [edit]

Some body armors employ alumina ceramic plates, unremarkably in combination with aramid or UHMWPE bankroll to achieve effectiveness against most burglarize threats. Alumina ceramic armor is readily available to almost civilians in jurisdictions where it is legal, simply is not considered war machine grade.^[25]

Abrasion protection [edit]

Aluminium oxide tin can be grown as a coating on aluminium by anodizing or by plasma electrolytic oxidation (run across the "Backdrop" to a higher place). Both the hardness and abrasion-resistant characteristics of the coating originate from the loftier strength of aluminium oxide, nonetheless the porous coating layer produced with conventional direct current anodizing procedures is within a sixty–70 Rockwell hardness C range^[26] 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 blanket is porous merely on the surface oxide layer while the lower oxide layers are much more than meaty than with standard DC anodizing procedures and present a college crystallinity due to the oxide layers being remelted and densified to obtain α-Al2O3 clusters with much college blanket hardness values circa 2000 Vickers hardness.^{[ citation needed ]}

Aluminium oxide output in 2005

Alumina is used to industry tiles which are fastened inside pulverized fuel lines and flue gas ducting on coal fired power stations to protect high wearable areas. They are not suitable for areas with high impact forces every bit these tiles are brittle and susceptible to breakage.

Electrical insulation [edit]

Aluminium oxide is an electrical insulator used as a substrate (silicon on sapphire) for integrated circuits but besides equally a tunnel barrier for the fabrication of superconducting devices such as unmarried-electron transistors and superconducting quantum interference devices (SQUIDs).

For its awarding every bit an electrical insulator in integrated circuits, where the conformal growth of a thin film is a prerequisite and the preferred growth mode is atomic layer deposition, Al₂O₃ films tin can be prepared by the chemical exchange between trimethylaluminum (Al(CH₃)_three) and H₂O:^[27]

2 Al(CH₃)₃ + 3 H₂O → Al₂O_three + 6 CH₄

H₂O in the higher up reaction tin be replaced by ozone (O_three) as the active oxidant and the following reaction then takes place:^{[28] [29]}

two Al(CH_three)₃ + O_three → Al₂O_three + 3 C_iiH₆

The Al₂O₃ films prepared using O₃ evidence 10–100 times lower leakage electric current density compared with those prepared by H_twoO.

Aluminium oxide, being a dielectric with relatively large band gap, is used every bit an insulating barrier in capacitors.^[30]

Other [edit]

In lighting, translucent aluminium oxide is used in some sodium vapor lamps.^[31] Aluminium oxide is likewise used in preparation of coating suspensions in compact fluorescent lamps.

In chemistry laboratories, aluminium oxide is a medium for chromatography, available in basic (pH nine.5), acidic (pH 4.5 when in water) and neutral formulations.

Health and medical applications include it as a material in hip replacements^[7] and nascency command pills.^[32]

It is used as a scintillator^[33] and dosimeter for radiation protection and therapy applications for its optically stimulated brilliance properties.^{[ commendation needed ]}

Insulation for high-temperature furnaces is frequently manufactured from aluminium oxide. Sometimes the insulation has varying percentages of silica depending on the temperature rating of the material. The insulation tin can be made in blanket, board, brick and loose fiber forms for various application requirements.

Small pieces of aluminium oxide are often used equally boiling chips in chemistry.

It is also used to make spark plug insulators.^[34]

Using a plasma spray process and mixed with titania, information technology is coated onto the braking surface of some bike rims to provide abrasion and article of clothing resistance.^{[ citation needed ]}

Virtually ceramic eyes on line-fishing rods are circular rings made from aluminium oxide.^{[ citation needed ]}

In its finest powdered (white) course, chosen Diamantine, aluminium oxide is used equally a superior polishing abrasive in watchmaking and clockmaking.^[35]

Aluminium oxide is also used in the blanket of stanchions in the motorcross and mountainbike industry. This coating is combined with molybdenumdisulfate to provide long term lubrication of the surface.^[36]

Run into too [edit]

• Aluminium oxide nanoparticle
• Bauxite tailings
• Beta-alumina solid electrolyte, a fast ion conductor
• Charged Droplets Release Experiment (CARE)
• List of alumina refineries
• Micro-Pulling-Down
• Transparent alumina

References [edit]

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34. ^ Farndon, John (2001). Aluminum . Marshall Cavendish. p. 19. ISBN9780761409472. Aluminum oxide is also used to make spark plug insulators.
35. ^ de Carle, Donald (1969). Practical Watch Repair. Due north.A.G. Printing Ltd. p. 164. ISBN0719800307.
36. ^ "Kashima Coat - Products / Services | Next-generation anodize boasting low-cal weight, high lubrication, and superb vesture resistance. The reply is Miyaki's Kashima Glaze".

External links [edit]

• CDC - NIOSH Pocket Guide to Chemical Hazards

Aluminum And Iron Iii Oxide,

Source: https://en.wikipedia.org/wiki/Aluminium_oxide

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