Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Alumina shopping experience:
1. Compare - without doubt the biggest advantage that the Alumina offers shoppers today is the ability to compare thousands of Alumina at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Alumina? Wrong! If the Alumina is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Alumina then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Alumina? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Alumina and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Alumina wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Alumina then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Alumina site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Alumina, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Alumina, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
{{Chembox new| Name = Aluminium oxide| ImageFile = Corundum-unit-cell-3D-balls.png| Section1 = {{Chembox Identifiers| CASNo = 1344-28-1 -->
| Section2 = {{Chembox Properties| MolarMass = 101.96 g/mol| Density = 3.97 g cm−3, solid| Solubility =
insoluble| MeltingPt = 2054 °C| BoilingPt = 2980 °C -->
| Section3 = {{Chembox Structure| Coordination = [octahedral -->
| Section4 = {{Chembox Thermochemistry| DeltaHf = −1675.7 kJ mol−1| Entropy = 50.92 J mol−1 K−1 -->
| Section7 = {{Chembox Hazards| EUClass = Not listed.| FlashPt = non-flammable -->
| Section8 = {{Chembox Related| OtherAnions =
aluminium hydroxide
[gallium oxideindium oxide
thallium oxide-->-->
Aluminium oxide is an amphoteric oxide of aluminium with the
chemical formula 23. It is also commonly referred to as
alumina in the mining,
ceramic and
materials science communities.
Properties
Aluminium oxide is an electrical Electrical insulation but has a relatively high thermal conductivity. In its most commonly occurring crystalline form, called corundum or α-aluminum oxide, its hardness makes it suitable for use as an
abrasive and as a component in cutting tools.
Aluminium oxide is responsible for metallic aluminium's resistance to
weathering. Metallic aluminium is very reactive with atmospheric oxygen, and a thin passivation layer of alumina quickly forms on any exposed aluminium surface. 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 alumina generated by anodising is typically amorphous, but discharge assisted oxidation processes such as
plasma electrolytic oxidation result in a significant proportion of crystalline alumina in the coating, enhancing its
hardness.
Aluminium oxide was taken off the United States Environmental Protection Agency's chemicals lists in 1988. Aluminum oxide is on EPA's TRI list if it is a fibrous form.
Natural occurrence
Corundum is the naturally occurring
crystalline form of aluminium oxide. ruby and
sapphires are gem-quality forms of corundum with their characteristic colors due to trace impurities in the corundum structure.
Crystal structure
The most common form of crystalline alumina, α-aluminum oxide, is known as
corundum and has a
close-packing (HCP) lattice structure.
Industrial Fabrication Process
Aluminium
oxide, also known as alumina, is the main component of
bauxite, the principal ore of aluminium. The largest
manufacturing in the world of alumina are
Alcoa,
Alcan and
Rusal. Companies which specialise in the production of speciality aluminium oxides and aluminium hydroxides include Alcan and Almatis, Inc.. The bauxite ore is made up of impure Al2O3, Fe2O3, and SiO2. These are then purified by the
Bayer process:
Al2O3 + 3H2O + 2NaOH + heat → 2NaAl(OH)4
The Fe2O3 does not dissolve in the base. The SiO2 dissolves as silicate Si(OH)62-. Upon filtering, Fe2O3 is removed. When the Bayer liquor is cooled, Al(OH)3 precipitates. The silicate remains in solution. Then:
2Al(OH)3 + heat → Al2O3 + 3H2O
The formed Al2O3 is alumina.
In 1961, GE developed "Lucalox", a transparent alumina used in
sodium vapor lamps.
In August
2004, scientists in the United States working for
3M developed a technique for making an alloy of aluminium oxide and
rare earth elements to produce a strong
glass called
transparent alumina.
As discussed above (in the "Properties" section), alumina can be grown as a
coating on aluminium by anodising or by plasma electrolytic oxidation.
Uses
Annual world production of alumina is approximately 65 million tonnes, over 90% of which is used in the manufacture of aluminium metal. Major uses for aluminium hydroxide include the manufacture of water treatment chemicals such as aluminium sulphate, Poly Aluminium Chloride and sodium aluminate. Large tonnages are also used in the manufacture of zeolites, coating titania pigments and as a fire retardants/smoke suppressant. The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications. Minor uses include use in toothpaste formulations, and as a medium for
chromatography. In this latter application alumina is available in the so-called Brockmann types neutral, basic (
pH 9.5) and acidic (pH 4.5 when in water). Aluminium oxide is also used in preparation of coating suspensions in
compact fluorescent lamps.
Al2O3 is also used in fluoride water filters. It is one of the few methods available to filter water soluble fluorides out of water.
Aluminum oxide is also used as a material in hip replacements.
Commercial uses
Because of aluminium oxide's position on the
Mohs scale of mineral hardness, (9), it is very widely used as an
abrasive as a significantly less expensive replacement for industrial diamonds. Many types of
sandpaper use aluminium oxide crystals. In addition, its low heat retention and specific heat makes it widely used in almost all grinding operations, particularly metalworking tools.
Aluminium oxide is used in certain
CD/DVD cleaning kits. Alumina will polish the media surface, leaving it clean and relatively scratch-free.
Alumina is also the
byproduct of hydrogen generation for the purposes of fuel generation when water is added to pellets comprised of aluminum and gallium. The other byproduct of the reaction is gallium.
Most pre-finished wood
flooring now uses aluminum oxide as a hard protective
coating.
See also
References
-->
External links
- International Chemical Safety Card 0351
- PhysicsWeb article on Transparent alumina
{{Chembox new| Name = Aluminium oxide| ImageFile = Corundum-unit-cell-3D-balls.png| Section1 = {{Chembox Identifiers| CASNo = 1344-28-1 -->
| Section2 = {{Chembox Properties| MolarMass = 101.96 g/mol| Density = 3.97 g cm−3, solid| Solubility =
insoluble| MeltingPt = 2054 °C| BoilingPt = 2980 °C -->
| Section3 = {{Chembox Structure| Coordination = [octahedral -->
| Section4 = {{Chembox Thermochemistry| DeltaHf = −1675.7 kJ mol−1| Entropy = 50.92 J mol−1 K−1 -->
| Section7 = {{Chembox Hazards| EUClass = Not listed.| FlashPt = non-flammable -->
| Section8 = {{Chembox Related| OtherAnions = aluminium hydroxide
[gallium oxide
indium oxide
thallium oxide-->-->
Aluminium oxide is an
amphoteric oxide of
aluminium with the chemical formula 23. It is also commonly referred to as
alumina in the mining, ceramic and
materials science communities.
Properties
Aluminium oxide is an electrical Electrical insulation but has a relatively high thermal conductivity. In its most commonly occurring crystalline form, called
corundum or α-aluminum oxide, its hardness makes it suitable for use as an abrasive and as a component in
cutting tools.
Aluminium oxide is responsible for metallic aluminium's resistance to
weathering. Metallic aluminium is very reactive with atmospheric
oxygen, and a thin
passivation layer of alumina quickly forms on any exposed aluminium surface. 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 alumina generated by anodising is typically amorphous, but discharge assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline alumina in the coating, enhancing its
hardness.
Aluminium oxide was taken off the United States Environmental Protection Agency's chemicals lists in
1988. Aluminum oxide is on EPA's TRI list if it is a fibrous form.
Natural occurrence
Corundum is the naturally occurring
crystalline form of aluminium oxide.
ruby and
sapphires are gem-quality forms of corundum with their characteristic colors due to trace impurities in the corundum structure.
Crystal structure
The most common form of crystalline alumina, α-aluminum oxide, is known as corundum and has a close-packing (HCP) lattice structure.
Industrial Fabrication Process
Aluminium
oxide, also known as alumina, is the main component of bauxite, the principal
ore of aluminium. The largest manufacturing in the world of alumina are Alcoa, Alcan and Rusal. Companies which specialise in the production of speciality aluminium oxides and aluminium hydroxides include Alcan and Almatis, Inc.. The bauxite ore is made up of impure Al2O3, Fe2O3, and SiO2. These are then purified by the Bayer process:
Al2O3 + 3H2O + 2NaOH + heat → 2NaAl(OH)4
The Fe2O3 does not dissolve in the base. The SiO2 dissolves as silicate Si(OH)62-. Upon filtering, Fe2O3 is removed. When the Bayer liquor is cooled, Al(OH)3 precipitates. The silicate remains in solution. Then:
2Al(OH)3 + heat → Al2O3 + 3H2O
The formed Al2O3 is alumina.
In 1961, GE developed "
Lucalox", a transparent alumina used in sodium vapor lamps.
In August 2004, scientists in the United States working for 3M developed a technique for making an alloy of aluminium oxide and rare earth elements to produce a strong glass called transparent alumina.
As discussed above (in the "Properties" section), alumina can be grown as a
coating on aluminium by
anodising or by
plasma electrolytic oxidation.
Uses
Annual world production of alumina is approximately 65 million tonnes, over 90% of which is used in the manufacture of aluminium metal. Major uses for aluminium hydroxide include the manufacture of water treatment chemicals such as aluminium sulphate, Poly Aluminium Chloride and sodium aluminate. Large tonnages are also used in the manufacture of
zeolites, coating titania pigments and as a fire retardants/smoke suppressant. The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications. Minor uses include use in toothpaste formulations, and as a medium for
chromatography. In this latter application alumina is available in the so-called
Brockmann types neutral, basic (pH 9.5) and acidic (pH 4.5 when in water). Aluminium oxide is also used in preparation of coating suspensions in compact fluorescent lamps.
Al2O3 is also used in fluoride water filters. It is one of the few methods available to filter water soluble fluorides out of water.
Aluminum oxide is also used as a material in
hip replacements.
Commercial uses
Because of aluminium oxide's position on the
Mohs scale of mineral hardness, (9), it is very widely used as an abrasive as a significantly less expensive replacement for
industrial diamonds. Many types of sandpaper use aluminium oxide crystals. In addition, its low heat retention and specific heat makes it widely used in almost all grinding operations, particularly
metalworking tools.
Aluminium oxide is used in certain
CD/
DVD cleaning kits. Alumina will
polish the media surface, leaving it clean and relatively
scratch-free.
Alumina is also the byproduct of hydrogen generation for the purposes of fuel generation when water is added to pellets comprised of aluminum and gallium. The other byproduct of the reaction is gallium.
Most pre-finished
wood flooring now uses aluminum oxide as a hard protective
coating.
See also
References
-->
External links
- International Chemical Safety Card 0351
- PhysicsWeb article on Transparent alumina
Aluminium oxide - Wikipedia, the free encyclopedia
Aluminium oxide is an amphoteric oxide of aluminium with the chemical formula Al 2 O 3. It is also commonly referred to as alumina or aloxite [2] in the mining, ceramic and ...
Definition: alumina from Online Medical Dictionary
The Online Medical Dictionary is a searchable dictionary of definitions from medicine, science and technology.
alumina - Hutchinson encyclopedia article about alumina
Hutchinson encyclopedia article about alumina. alumina. Information about alumina in the Hutchinson encyclopedia.
alumina definition of alumina in the Free Online Encyclopedia.
Encyclopedia article about alumina. Information about alumina in the Columbia Encyclopedia, Computer Desktop Encyclopedia, computing dictionary.
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