Editing Aluminium oxide (section)

==Applications==
[[Image:2005alumina.PNG|thumb|upright=1.3|Aluminium oxide output in 2005]]
Known as ''alpha alumina'' in [[materials science]], and as ''alundum'' (in fused form) or ''aloxite''<ref name="CI14835">{{cite news| url = http://www.chemindustry.com/chemicals/14835.html| title = Aloxite| publisher = ChemIndustry.com database| access-date = 24 February 2007| url-status = live| archive-url = https://web.archive.org/web/20070625100844/http://www.chemindustry.com/chemicals/14835.html| archive-date = 25 June 2007}}</ref> in [[mining]] and [[ceramic]] communities, aluminium oxide finds wide use. Annual global production of aluminium oxide in 2015 was approximately 115 million [[tonne]]s, over 90% of which was used in the manufacture of aluminium metal.<ref name="azom" /> 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 [[Titanium dioxide|titania]] pigments, and as a fire retardant/smoke suppressant.

Over 90% of aluminium oxide, termed ''smelter grade alumina'' (SGA), is consumed for the production of aluminium, usually by the [[Hall–Héroult process]]. The remainder, termed ''specialty alumina'', is used in a wide variety of applications which take advantage of its inertness, temperature resistance and electrical resistance.<ref>{{cite book|chapter = Properties and uses of aluminium oxides and aluminium hydroxides|first = K. A.|last = Evans|title = The Chemistry of Aluminium, Indium and Gallium|editor-first = A. J.|editor-last = Downs|publisher = Blackie Academic|year = 1993|isbn = 978-0751401035}}</ref>

===Fillers===
Being fairly chemically inert and white, aluminium oxide is commonly used as a filler for plastics. Aluminium oxide is a common ingredient in [[sunscreen]]<ref>{{cite web |title=Alumina |url=https://incidecoder.com/ingredients/alumina |website=INCI Decoder |access-date=20 June 2023 |archive-url=https://web.archive.org/web/20230205144849/https://incidecoder.com/ingredients/alumina |archive-date=5 February 2023}}</ref> and is often also present in cosmetics such as blush, lipstick, and nail polish.<ref>{{cite web |title=Alumina (Ingredient Explained + Products) |url=https://skinsort.com/ingredients/alumina |website=SkinSort |access-date=15 October 2023 |archive-url=https://web.archive.org/web/20231015122803/https://skinsort.com/ingredients/alumina |archive-date=15 October 2023}}</ref>

===Glass===
Many formulations of [[glass]] have aluminium oxide as an ingredient.<ref>{{Cite book|url=https://books.google.com/books?id=C2_LBQAAQBAJ&q=some+glass+contain+aluminum+oxide&pg=PA73|title=Sterile Drug Products: Formulation, Packaging, Manufacturing and Quality|last=Akers|first=Michael J.|date=2016-04-19|publisher=CRC Press|isbn=9781420020564|language=en}}</ref> Aluminosilicate glass 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 its largest scale application, aluminium oxide is the catalyst in the [[Claus process]] for converting hydrogen sulfide waste gases into elemental sulfur in refineries. It is also useful for [[Dehydration reaction|dehydration]] of [[Alcohol (chemistry)|alcohol]]s to [[alkene]]s.

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.<ref>Hudson, L. Keith; Misra, Chanakya; Perrotta, Anthony J.; Wefers, Karl and Williams, F. S. (2002)  "Aluminum Oxide" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a01_557}}.</ref>

===Abrasion===
Aluminium oxide is used for its hardness and strength. Its naturally occurring form, [[corundum]], is a 9 on the [[Mohs scale of mineral hardness]] (just below diamond). It 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, its low heat retention and low [[specific heat]] make it widely used in grinding operations, particularly [[metalworking|cutoff]] tools. As the powdery abrasive mineral [[aloxite]], it is a major component, along with [[silica]], of the [[Cue stick|cue tip]] "chalk" used in [[Cue sports|billiards]]. Aluminium oxide powder is used in some [[Compact disc|CD]]/[[DVD]] [[polishing]] and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste.  It 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===
{{Main|Alumina effect pigment}}
Aluminium oxide flakes are used in paint for reflective decorative effects, such as in the automotive or cosmetic industries.{{citation needed|date=May 2019}}

===Biomedical applications===
Aluminium oxide is a representative of bioinert ceramics.<ref>{{cite book |last1=Ishikawa|first1=K. |last2=Matsuya |first2= S. |date=2003 |title=Comprehensive Structural Integrity |url=https://www.sciencedirect.com/referencework/9780080437491/comprehensive-structural-integrity |publisher=Elsevier Science |volume=9 |pages=169–214 |isbn=978-0-08-043749-1 |access-date=May 27, 2024}}</ref> Due to its excellent biocompatibility, high strength, and wear resistance, alumina ceramics are used in medical applications to manufacture artificial bones and joints.<ref>{{cite web |url=https://www.preciseceramic.com/products/alumina-al2o3.html |title=Alumina (Al2O3), Aluminum Oxide |website=Precise Ceramic |access-date=May 27, 2024}}</ref> In this case, aluminium oxide is used to coat the surfaces of medical implants to give biocompatibility and corrosion resistance.<ref>[https://powder.samaterials.com/aluminum-oxide-game-changer-in-optical-coating-technology.html Aluminum Oxide: A Game Changer in Optical Coating Technology], Stanford Advanced Materials.</ref> It is also used for manufacturing dental implants, joint replacements, and other medical devices.<ref>{{cite web |url=https://www.usgs.gov/media/images/metals-and-minerals-medical-implants|title=Metals and Minerals in Medical Implants |website=USGS |date=15 March 2021 |access-date=May 27, 2024}}</ref>

===Composite fiber===
Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications (e.g., Fiber FP, Nextel 610, Nextel 720).<ref name=mallick>{{cite book|last=Mallick|first=P.K.|title=Fiber-reinforced composites materials, manufacturing, and design|year=2008|publisher=CRC Press|location=Boca Raton, FL|isbn=978-0-8493-4205-9|pages=Ch.2.1.7|edition=3rd ed., [expanded and rev. ed.]}}</ref>  Alumina [[nanofibers]] in particular have become a research field of interest.

===Armor===
Some body armors utilize alumina ceramic plates, usually in combination with aramid or UHMWPE backing to achieve effectiveness against most rifle threats. Alumina ceramic armor is readily available to most civilians in jurisdictions where it is legal, but is not considered military grade.<ref>{{cite web |title=Ballistic Resistance of Body Armor |url=https://www.ncjrs.gov/pdffiles1/nij/223054.pdf |website=US Department of Justice |publisher=NIJ |access-date=31 August 2018}}</ref>

===Abrasion protection===
An aluminium oxide layer can be grown as a protective coating on aluminium by [[anodizing]] or by [[plasma electrolytic oxidation]] (see the "Properties" above). 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<ref>{{cite web|first=Joseph H.|last=Osborn|title=understanding and specifying anodizing: what a manufacturer needs to know|url=http://www.omwcorp.com/understandingano/anoindex.html|website=OMW Corporation|year=2014|url-status=dead|archive-url=https://web.archive.org/web/20161120010024/http://www.omwcorp.com/understandingano/anoindex.html|archive-date=2016-11-20|access-date=2018-06-02}}</ref> 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.{{Citation needed|date=December 2019|reason=removed citation to content from predatory publisher}}

Alumina 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. They are not suitable for areas with high impact forces as these tiles are brittle and susceptible to breakage.

===Electrical insulation===
Aluminium oxide is an electrical [[insulator (electricity)|insulator]] used as a substrate ([[silicon on sapphire]]) for [[integrated circuits]],<ref>{{cite book |last1=Butterfield |first1=Andrew |last2=Szymanski |first2=John |year=2018 |title=Dictionary of Electronics and Electrical Engineering |publisher=Oxford University Press |url=https://books.google.com/books?id=UV9gDwAAQBAJ&dq=Aluminium+oxide+is+an+electrical+insulator+used+as+a+substrate+for+integrated+circuits&pg=PT922 |access-date=Sep 7, 2024 |isbn=9780198725725}}</ref> but also as a [[quantum tunneling|tunnel barrier]] for the fabrication of [[superconducting]] devices such as [[single-electron transistor]]s, superconducting quantum interference devices ([[SQUID]]s) and [[Superconducting quantum computing|superconducting qubits]].<ref>{{cite web |url=https://www.preciseceramic.com/blog/why-aluminum-oxide-is-used-in-tools.html |title=Why Aluminum Oxide is Used in Tools? |date=Jan 31, 2024 |last=Ross |first=Lisa |website=Advanced Ceramic Materials |access-date=Sep 7, 2024}}</ref><ref>{{cite web |url=https://phys.org/news/2021-09-materials-superconducting-qubits.html |title=Materials for superconducting qubits |first=Thamarasee |last=Jeewandara |date=Sep 2, 2021 |website=Phys |access-date=Sep 7, 2024}}</ref>

For its application as 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]], Al<sub>2</sub>O<sub>3</sub> films can be prepared by the chemical exchange between [[trimethylaluminium]] (Al(CH<sub>3</sub>)<sub>3</sub>) and H<sub>2</sub>O:<ref>{{Cite journal|author=Higashi GS, Fleming |title= Sequential surface chemical reaction limited growth of high quality Al<sub>2</sub>O<sub>3</sub> dielectrics |journal=Appl. Phys. Lett.|volume=55 |issue= 19|pages=1963–65 |year=1989 |doi=10.1063/1.102337|bibcode = 1989ApPhL..55.1963H }}</ref>

:2 Al(CH<sub>3</sub>)<sub>3</sub> + 3 H<sub>2</sub>O → Al<sub>2</sub>O<sub>3</sub> + 6 CH<sub>4</sub>

H<sub>2</sub>O in the above reaction can be replaced by [[ozone]] (O<sub>3</sub>) as the active oxidant and the following reaction then takes place:<ref>{{Cite journal|author1=Kim JB |author2=Kwon DR |author3=Chakrabarti K |author4=Lee Chongmu |author5=Oh KY |author6=Lee JH |title= Improvement in Al<sub>2</sub>O<sub>3</sub> dielectric behavior by using ozone as an oxidant for the atomic layer deposition technique
| journal=J. Appl. Phys. |volume=92 |issue= 11| pages=6739–42 |year=2002 |doi=10.1063/1.1515951|bibcode = 2002JAP....92.6739K }}</ref><ref>{{Cite journal|author1=Kim, Jaebum |author2=Chakrabarti, Kuntal |author3=Lee, Jinho |author4=Oh, Ki-Young |author5=Lee, Chongmu |title= Effects of ozone as an oxygen source on the properties of the Al<sub>2</sub>O<sub>3</sub> thin films prepared by atomic layer deposition |journal=Mater Chem Phys |volume=78 |issue= 3| pages=733–38 |year=2003 |doi=10.1016/S0254-0584(02)00375-9}}</ref>

:2 Al(CH<sub>3</sub>)<sub>3</sub> + O<sub>3</sub> → Al<sub>2</sub>O<sub>3</sub> + 3 C<sub>2</sub>H<sub>6</sub>

The Al<sub>2</sub>O<sub>3</sub> films prepared using O<sub>3</sub> show 10–100 times lower leakage current density compared with those prepared by H<sub>2</sub>O.

Aluminium oxide, being a dielectric with relatively large [[band gap]], is used as an insulating barrier in [[capacitors]].<ref name="Belkin">{{cite journal |last1=Belkin |first1=A. |last2=Bezryadin |first2=A. |last3=Hendren |first3=L. |last4=Hubler |first4=A. |title=Recovery of Alumina Nanocapacitors after High Voltage Breakdown |journal=Scientific Reports |date=20 April 2017 |volume=7 |issue=1 |pages=932 |doi=10.1038/s41598-017-01007-9|pmid=28428625 |pmc=5430567 |bibcode=2017NatSR...7..932B }}</ref>

===Other===
[[File:Aluminum Oxide Ice Cream IMG20250316190022.jpg|thumb|Aluminium residue from a '50s vintage ice cream scoop.]]

Before the advent of domestic [[plastics]] aluminium [[ice cream scoop]]s would with wear and tear leave aluminium residue.<ref>{{cite web | url=https://www.budget101.com/tips-n-tricks/4128-how-to-fix-oxidized-kitchen-utensils/ | title=How to Fix Oxidized Kitchen Utensils - by Budget101 | date=22 October 2020 }}</ref><ref>{{cite journal | pmc=5388732 | date=2017 | last1=Stahl | first1=T. | last2=Falk | first2=S. | last3=Rohrbeck | first3=A. | last4=Georgii | first4=S. | last5=Herzog | first5=C. | last6=Wiegand | first6=A. | last7=Hotz | first7=S. | last8=Boschek | first8=B. | last9=Zorn | first9=H. | last10=Brunn | first10=H. | title=Migration of aluminum from food contact materials to food—a health risk for consumers? Part I of III: Exposure to aluminum, release of aluminum, tolerable weekly intake (TWI), toxicological effects of aluminum, study design, and methods | journal=Environmental Sciences Europe | volume=29 | issue=1 | page=19 | doi=10.1186/s12302-017-0116-y | doi-access=free | pmid=28458989 }}</ref> 

In lighting, translucent aluminium oxide is used in some [[sodium vapor lamp]]s.<ref>{{cite web|url=http://www.ge.com/innovation/timeline/eras/science_and_research.html|title=GE Innovation Timeline 1957–1970|access-date=2009-01-12| archive-url= https://web.archive.org/web/20090216233917/http://www.ge.com/innovation/timeline/eras/science_and_research.html| archive-date= 16 February 2009 | url-status= live}}</ref> Aluminium oxide is also used in preparation of coating suspensions in [[compact fluorescent lamp]]s.

In chemistry laboratories, aluminium oxide is a medium for [[chromatography]], available in [[Base (chemistry)|basic]] (pH&nbsp;9.5), [[acid]]ic (pH&nbsp;4.5 when in water) and neutral formulations. Additionally, small pieces of aluminium oxide are often used as [[boiling chips]].

Health and medical applications include it as a material in [[hip replacement]]s<ref name="azom" /> and [[Oral contraceptive pill|birth control pills]].<ref>{{Cite web|url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=75bb0024-8f1a-4036-9acd-006ea430f3b7#|title=DailyMed - JUNEL FE 1/20- norethindrone acetate and ethinyl estradiol, and ferrous fumarate|website=dailymed.nlm.nih.gov|access-date=2017-03-13|url-status=live|archive-url=https://web.archive.org/web/20170313130132/https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=75bb0024-8f1a-4036-9acd-006ea430f3b7|archive-date=2017-03-13}}</ref>

It is used as a [[scintillator]]<ref>{{Cite journal|author=V.B. Mikhailik, H. Kraus |title= Low-temperature spectroscopic and scintillation characterisation of Ti-doped Al<sub>2</sub>O<sub>3</sub>|journal=Nucl. Instr. Phys. Res. A|volume=546 |issue= 3|pages=523–534 |year=2005 |doi=10.1016/j.nima.2005.02.033|bibcode= 2005NIMPA.546..523M}}</ref> 
and [[dosimeter]] for radiation protection and therapy applications for its [[optically stimulated luminescence]] properties.{{citation needed|date=August 2014}}

Insulation for high-temperature furnaces is often manufactured from aluminium oxide.  Sometimes the insulation contains a percentage 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.

It is also used to make [[spark plug]] [[insulator (electricity)|insulator]]s.<ref>{{Cite book|url=https://archive.org/details/aluminiumtheeleme00john|url-access=registration|page=[https://archive.org/details/aluminiumtheeleme00john/page/19 19]|quote=Aluminium oxide is also used to make spark plug insulators.|title=Aluminium|last=Farndon|first=John|date=2001|publisher=Marshall Cavendish|isbn=9780761409472|language=en}}</ref>

Using a [[Plasma spraying|plasma spray]] process and mixed with [[Titanium dioxide|titania]], it is coated onto the braking surface of some [[bicycle]] rims to provide abrasion and wear resistance.{{Citation needed|date=March 2011}}
 
Most ceramic eyes on fishing rods are circular rings made from aluminium oxide.{{citation needed|date=August 2014}}

In its finest powdered (white) form, called Diamantine, aluminium oxide is used as a superior polishing abrasive in watchmaking and clockmaking.<ref>{{Cite book | title=Practical Watch Repair|pages=164 | last=de Carle|first=Donald|publisher=N.A.G. Press Ltd.|isbn=0719800307|language=en|year=1969 }}</ref>

Aluminium oxide is also used in the coating of stanchions in the motocross and mountain bike industries. 
This coating is combined with [[molybdenum disulfide]] to provide long term lubrication of the surface.<ref>{{Cite web|url=http://www.kashima-coat.com/global/service/kashima-coat/|title = Kashima Coat - Products / Services &#124; Next-generation anodize boasting light weight, high lubrication, and superb wear resistance. The answer is Miyaki's Kashima Coat}}</ref>