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Thie page is in need of some organization, even if its a short article. I put the industrial fabrication stuff on the bottom with a header. Fresheneesz 02:08, 25 November 2005 (UTC)
IS Al2O3 ionic or covalent?
Altough a category "Suppliers" exists in other pages, Aldrich is here linked in the section for normal links. How can I decide, if this link is advertisment, neutral or that someone has been paid for adding this link?
http://en.wikipedia.org/wiki/User_talk:213.188.227.119
Best regards
Does anyone know how to break this stuff down without using a thermic lance?
Depends how much you want to break down. If you just want to break down the surface oxide on the metal to make the metal react you can just place it in a weak salt (NaCl) solution!
I am curious as to the health risk with aluminium oxide. We probably all have heard the stories about aluminium pans and rhubarb. I saw a mention that aluminium pans haven't been confirmed as a health risk at all in the Al. page.
When was aluminium oxide first dicovered or first made, i just need to know dates and names! pls...
Grinding wheels . . .
have been around since man first used them to convert wheat into flour . . .
and aluminum is an integral part of its history . . .
This was the best source I could find about the history of the aluminum as grinding material and probably as close as you will ever get to the truth about the originators of aluminum . . .
grinding wheels @ Answers Dot Com
Morehugh 19:16, 16 January 2007 (UTC)
No! This is a chemistry article about the chemical, corundum is a mineralogy article about the naturally occurring mineral. Vsmith 15:32, 8 January 2006 (UTC)
Oppose merger I agree with the above poster. Would an article about diamond or charcoal be merged with an article about carbon?-- 24.217.183.224 08:21, 9 January 2006 (UTC)
Maybe I will get to this sometime but if someone else wants to distill the below to add it might be good.
- What about the various phases of alumina (alpha, gamma, etc) and what temps they form at
- What about its uses in the field of catalyst research, ceramics, biomedicine, and pottery
hi
sources:
http://ceramic-materials.com/cermat/material/41.html http://ceramic-materials.com/cermat/oxide/al2o3.html http://www.azom.com/details.asp?ArticleID=52
I would like to see more about the Crystal Structure and bonding. Also Alumina has a very high melting point and therefore it is commonly used as a refractory material.
Thermal conductivity of pure alumina should be around 25-35 W/(m.K).
This picture of Al2O3-based plastics seems like a poor addition to the article. It doesn't show the common mineral form, and it's a poorly-taken photo to boot. Any objections to removing it? Anyone have a better example? Alvis 06:15, 2 August 2006 (UTC) (moved to bottom of page Dirk Beetstra T C 07:19, 2 August 2006 (UTC))
Two people showing support (2 weeks), I have removed the image. Too bad no better image is available. -- Dirk Beetstra T C 16:10, 16 August 2006 (UTC)
From the article:
The most common form of crystalline alumina, α-aluminum oxide, is known as corundum and has a hexagonal close packed (HCP) lattice structure. The table on this page lists it as cubic, which is incorrect.
... if the sidbar is wrong, why isn't it corrected. This might need some attention from some wikipedians (I'm just a passer-by.) 129.241.129.67 13:15, 6 May 2007 (UTC)
In the Properties section I'm surprised by the statement:
Aluminium oxide is a good thermal insulator and electrical insulator.
I thought that alumina was a relative good conductor of heat for an electrical insulator. See for example http://www.accuratus.com/alumox.html (from the numbers given for the thermal conductivity appears to be very sensitive to impurities). 155.198.213.89 09:49, 26 September 2007 (UTC)
Alumina fiber is a good thermal insulator.
Thermal conductivity of pure alumina should be around 25-35 W/(m.K).
It says in this article that "aluminium oxide is the main component of bauxite". However, the bauxite article says that "It consists largely of the minerals gibbsite Al(OH)3, boehmite and diaspore AlOOH, together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2." No aluminium oxide there. So which is correct?-- BillFlis 06:56, 27 October 2007 (UTC)
The description of the bayer process chemistry in the alumina article is inconsistent with the description in the bayer process article. In particular, the alumina article claims that both the aluminium oxides and the silicon dioxide (ie quartz ) disolve in the NaOH solution, wheras the bayer process article does not claim that the SiO2 dissolves. The latter is probably correct. I don't think common sand dissolves in caustic soda even at 175 C. Eregli bob ( talk) 04:27, 15 December 2007 (UTC)
Outside the context of these industrial processes, silica does indeed dissolve in alkali. That's one of the mechanisms by which a base bath (sat. KOH/NaOH in IPA/EtOH) cleans laboratory glassware - it removes a thin film of the glass by dissolving silica to give silicates. -- Rifleman 82 ( talk) 13:56, 15 December 2007 (UTC)
Is "alundom" also alumina? I see it mentioned in old texts, but cannot find a defintion of what it is. DonPMitchell ( talk) 01:38, 16 July 2008 (UTC)
Anyone know the zero-point of charge of alumina? Need to perform SEM. —Preceding unsigned comment added by Bottiglieri1 ( talk • contribs) 20:07, 30 July 2008 (UTC)
This product should not be used for polishing titanium products, as it will cause corrosion. —Preceding unsigned comment added by 81.130.21.26 ( talk) 12:27, 1 September 2009 (UTC)
that model doesn't make sense, it looks like a hundred times that M. C. Escher thing :-) I can't imagine how this looks in reality. -- androl ( talk) 18:10, 5 October 2009 (UTC)
An image used in this article,
File:CM Furnaces 1700C Box Furnace.jpg, has been nominated for speedy deletion at
Wikimedia Commons for the following reason: Copyright violations
Don't panic; deletions can take a little longer at Commons than they do on Wikipedia. This gives you an opportunity to contest the deletion (although please review Commons guidelines before doing so). The best way to contest this form of deletion is by posting on the image talk page.
This notification is provided by a Bot -- CommonsNotificationBot ( talk) 11:09, 30 December 2011 (UTC) |
The table to the right of the article says it's white, but abrasive paper and old aluminium cookware surface 'oxide' appears very much dark grey, so i'm confused. — Preceding unsigned comment added by 79.66.215.175 ( talk) 17:39, 9 August 2012 (UTC)
Hi I guess that it will be useful to enter " Thermal expansion coefficient of Aluminum Oxide " in this article with the same units of measure in " Aluminum " article .
Thermal Expansivity, 20 - 1000 C : 8.0 um/mK (reference:
http://www-ferp.ucsd.edu/LIB/PROPS/PANOS/al2o3.html)
I looked up alumina, not "aluminia," so why does this article use the hypercorrection "aluminium oxide" instead of plain aluminum oxide? 96.231.17.143 ( talk) 18:45, 2 August 2014 (UTC)
According to Chemical Abstracts, 608,616 reports mention alumina, of which 23347 appeared since the year 2018, of which 265 were reviews (i.e. suitable for WP:SECONDARY). Preliminary conclusion: citations to primary literature are not feasible or suitable.-- Smokefoot ( talk) 22:18, 9 April 2018 (UTC)
This comment, posted by Sapphireringco was completely unrelated to the article, and appeared to be a promotion for a company. Deleted by Dinithi2 ( talk) 01:58, 8 October 2018 (UTC)
Does it become an electrical conductor when molten ? if so, why/how ? - Rod57 ( talk) 14:44, 20 October 2018 (UTC)
I came to this article looking for the hardness of aluminium oxide, as it is an abrasive. There are passing mentions, but I cannot find anything like a clear statement of its hardness. Please would someone knowledgeable add this information or clarify the subject ? Many thanks ! Darkman101 ( talk) 06:15, 1 January 2019 (UTC)
There's a boiling point listed for Al2O3, and it's not listed as "decomposes", but I recall this from John D. Clark's book "Ignition":
"As an example of the first, calculations were made for years on systems containing aluminum, using thermodynamic data on gaseous Al2O3 calculated from its assumed structure. And the results didn't agree too well with the experimental performances. And then an inconsiderate investigator proved that gaseous Al2O3 didn't exist. Red faces all over the place."
I've also not seen any reference to gaseous Al2O3 in modern literature regarding the topic (e.g. regarding the ongoing attempts to develop a working carbothermic method of refining aluminium metal, which due to the extreme temperatures involved must consider gaseous species such as aluminium vapour and Al2O).
Should it therefore be listed as "decomposes"? Magic9mushroom ( talk) 03:46, 24 August 2019 (UTC)
The article does mention its use in capacitors, and otherwise as an insulator, but doesn't give its dielectric strength. That is, the volts per (length unit) that it can stand before dielectric breakdown. And specifically the hydrated form in electrolytic capacitors. Gah4 ( talk) 18:39, 29 March 2022 (UTC)
This
level-5 vital article is rated B-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||||||||||
|
Thie page is in need of some organization, even if its a short article. I put the industrial fabrication stuff on the bottom with a header. Fresheneesz 02:08, 25 November 2005 (UTC)
IS Al2O3 ionic or covalent?
Altough a category "Suppliers" exists in other pages, Aldrich is here linked in the section for normal links. How can I decide, if this link is advertisment, neutral or that someone has been paid for adding this link?
http://en.wikipedia.org/wiki/User_talk:213.188.227.119
Best regards
Does anyone know how to break this stuff down without using a thermic lance?
Depends how much you want to break down. If you just want to break down the surface oxide on the metal to make the metal react you can just place it in a weak salt (NaCl) solution!
I am curious as to the health risk with aluminium oxide. We probably all have heard the stories about aluminium pans and rhubarb. I saw a mention that aluminium pans haven't been confirmed as a health risk at all in the Al. page.
When was aluminium oxide first dicovered or first made, i just need to know dates and names! pls...
Grinding wheels . . .
have been around since man first used them to convert wheat into flour . . .
and aluminum is an integral part of its history . . .
This was the best source I could find about the history of the aluminum as grinding material and probably as close as you will ever get to the truth about the originators of aluminum . . .
grinding wheels @ Answers Dot Com
Morehugh 19:16, 16 January 2007 (UTC)
No! This is a chemistry article about the chemical, corundum is a mineralogy article about the naturally occurring mineral. Vsmith 15:32, 8 January 2006 (UTC)
Oppose merger I agree with the above poster. Would an article about diamond or charcoal be merged with an article about carbon?-- 24.217.183.224 08:21, 9 January 2006 (UTC)
Maybe I will get to this sometime but if someone else wants to distill the below to add it might be good.
- What about the various phases of alumina (alpha, gamma, etc) and what temps they form at
- What about its uses in the field of catalyst research, ceramics, biomedicine, and pottery
hi
sources:
http://ceramic-materials.com/cermat/material/41.html http://ceramic-materials.com/cermat/oxide/al2o3.html http://www.azom.com/details.asp?ArticleID=52
I would like to see more about the Crystal Structure and bonding. Also Alumina has a very high melting point and therefore it is commonly used as a refractory material.
Thermal conductivity of pure alumina should be around 25-35 W/(m.K).
This picture of Al2O3-based plastics seems like a poor addition to the article. It doesn't show the common mineral form, and it's a poorly-taken photo to boot. Any objections to removing it? Anyone have a better example? Alvis 06:15, 2 August 2006 (UTC) (moved to bottom of page Dirk Beetstra T C 07:19, 2 August 2006 (UTC))
Two people showing support (2 weeks), I have removed the image. Too bad no better image is available. -- Dirk Beetstra T C 16:10, 16 August 2006 (UTC)
From the article:
The most common form of crystalline alumina, α-aluminum oxide, is known as corundum and has a hexagonal close packed (HCP) lattice structure. The table on this page lists it as cubic, which is incorrect.
... if the sidbar is wrong, why isn't it corrected. This might need some attention from some wikipedians (I'm just a passer-by.) 129.241.129.67 13:15, 6 May 2007 (UTC)
In the Properties section I'm surprised by the statement:
Aluminium oxide is a good thermal insulator and electrical insulator.
I thought that alumina was a relative good conductor of heat for an electrical insulator. See for example http://www.accuratus.com/alumox.html (from the numbers given for the thermal conductivity appears to be very sensitive to impurities). 155.198.213.89 09:49, 26 September 2007 (UTC)
Alumina fiber is a good thermal insulator.
Thermal conductivity of pure alumina should be around 25-35 W/(m.K).
It says in this article that "aluminium oxide is the main component of bauxite". However, the bauxite article says that "It consists largely of the minerals gibbsite Al(OH)3, boehmite and diaspore AlOOH, together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2." No aluminium oxide there. So which is correct?-- BillFlis 06:56, 27 October 2007 (UTC)
The description of the bayer process chemistry in the alumina article is inconsistent with the description in the bayer process article. In particular, the alumina article claims that both the aluminium oxides and the silicon dioxide (ie quartz ) disolve in the NaOH solution, wheras the bayer process article does not claim that the SiO2 dissolves. The latter is probably correct. I don't think common sand dissolves in caustic soda even at 175 C. Eregli bob ( talk) 04:27, 15 December 2007 (UTC)
Outside the context of these industrial processes, silica does indeed dissolve in alkali. That's one of the mechanisms by which a base bath (sat. KOH/NaOH in IPA/EtOH) cleans laboratory glassware - it removes a thin film of the glass by dissolving silica to give silicates. -- Rifleman 82 ( talk) 13:56, 15 December 2007 (UTC)
Is "alundom" also alumina? I see it mentioned in old texts, but cannot find a defintion of what it is. DonPMitchell ( talk) 01:38, 16 July 2008 (UTC)
Anyone know the zero-point of charge of alumina? Need to perform SEM. —Preceding unsigned comment added by Bottiglieri1 ( talk • contribs) 20:07, 30 July 2008 (UTC)
This product should not be used for polishing titanium products, as it will cause corrosion. —Preceding unsigned comment added by 81.130.21.26 ( talk) 12:27, 1 September 2009 (UTC)
that model doesn't make sense, it looks like a hundred times that M. C. Escher thing :-) I can't imagine how this looks in reality. -- androl ( talk) 18:10, 5 October 2009 (UTC)
An image used in this article,
File:CM Furnaces 1700C Box Furnace.jpg, has been nominated for speedy deletion at
Wikimedia Commons for the following reason: Copyright violations
Don't panic; deletions can take a little longer at Commons than they do on Wikipedia. This gives you an opportunity to contest the deletion (although please review Commons guidelines before doing so). The best way to contest this form of deletion is by posting on the image talk page.
This notification is provided by a Bot -- CommonsNotificationBot ( talk) 11:09, 30 December 2011 (UTC) |
The table to the right of the article says it's white, but abrasive paper and old aluminium cookware surface 'oxide' appears very much dark grey, so i'm confused. — Preceding unsigned comment added by 79.66.215.175 ( talk) 17:39, 9 August 2012 (UTC)
Hi I guess that it will be useful to enter " Thermal expansion coefficient of Aluminum Oxide " in this article with the same units of measure in " Aluminum " article .
Thermal Expansivity, 20 - 1000 C : 8.0 um/mK (reference:
http://www-ferp.ucsd.edu/LIB/PROPS/PANOS/al2o3.html)
I looked up alumina, not "aluminia," so why does this article use the hypercorrection "aluminium oxide" instead of plain aluminum oxide? 96.231.17.143 ( talk) 18:45, 2 August 2014 (UTC)
According to Chemical Abstracts, 608,616 reports mention alumina, of which 23347 appeared since the year 2018, of which 265 were reviews (i.e. suitable for WP:SECONDARY). Preliminary conclusion: citations to primary literature are not feasible or suitable.-- Smokefoot ( talk) 22:18, 9 April 2018 (UTC)
This comment, posted by Sapphireringco was completely unrelated to the article, and appeared to be a promotion for a company. Deleted by Dinithi2 ( talk) 01:58, 8 October 2018 (UTC)
Does it become an electrical conductor when molten ? if so, why/how ? - Rod57 ( talk) 14:44, 20 October 2018 (UTC)
I came to this article looking for the hardness of aluminium oxide, as it is an abrasive. There are passing mentions, but I cannot find anything like a clear statement of its hardness. Please would someone knowledgeable add this information or clarify the subject ? Many thanks ! Darkman101 ( talk) 06:15, 1 January 2019 (UTC)
There's a boiling point listed for Al2O3, and it's not listed as "decomposes", but I recall this from John D. Clark's book "Ignition":
"As an example of the first, calculations were made for years on systems containing aluminum, using thermodynamic data on gaseous Al2O3 calculated from its assumed structure. And the results didn't agree too well with the experimental performances. And then an inconsiderate investigator proved that gaseous Al2O3 didn't exist. Red faces all over the place."
I've also not seen any reference to gaseous Al2O3 in modern literature regarding the topic (e.g. regarding the ongoing attempts to develop a working carbothermic method of refining aluminium metal, which due to the extreme temperatures involved must consider gaseous species such as aluminium vapour and Al2O).
Should it therefore be listed as "decomposes"? Magic9mushroom ( talk) 03:46, 24 August 2019 (UTC)
The article does mention its use in capacitors, and otherwise as an insulator, but doesn't give its dielectric strength. That is, the volts per (length unit) that it can stand before dielectric breakdown. And specifically the hydrated form in electrolytic capacitors. Gah4 ( talk) 18:39, 29 March 2022 (UTC)