FreeShip- Alumina Oxide, Calcined- (Prompt rebate on orders with 3 or more FreeShip items!)

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Note this is a calcined alumina oxide for ceramic use. It is not an abrasive.
Not all sizes are pictured.

This 325 mesh alumina oxide is a variety of the material more commonly called "aluminum oxide", Al2O3. It's one of those materials which have very many varieties and names, depending on the purity and the manufacturing process. This is a type that has the word "alumina" in it. Usually the descriptor "alumina" is an indicator that the material is a high fire ceramic or refractory, which this material is. Aluminas are also usually calcined, as is this material. Aluminum oxide and alumina have the same chemical name (Al2O3), but they differ in the way they are processed, in physical properties, and in appearance.
Although there's no reason this could not be called aluminum oxide, that term is usually reserved for the abrasive type of Al2O3, most often dark brown or black, very tough, hard, and with sharp particle shapes (although there is also an abrasive type that's white). "Corundum" is a natural alumina mineral (AlO3) which, if in single pure crystals are called ruby and sapphire.
But alumina oxide for art and industrial ceramics is almost all refined from the ore bauxite from which comes both hydrated alumina (ATH, Alumina Trihydrate), pure alumina (AlO3), and the metal aluminum.

Alumina is in clays, and usually the more alumina a clay has, the higher its firing temperature. It's also used in ceramic glazes in which it influences the appearance, vitrification, and strength of the glaze. It also stabilizes flux in glazes and helps prevent devitrification. In clay bodies it is used for the hardness, strength, toughness, and vitrification it imparts. High temperature porcelains contain alumina. Special industrial ceramics contain high amounts of alumina to impart special properties.
Pure alumina is a relatively expensive raw material. In ceramics the need for high physical properties must be balanced with cost, both for the material and the energy necessary to fire it to the high temperatures needed.

The terminology used to describe aluminum oxide or alumina is highly variable. "Aluminum oxide" is a loose term. It can be: 1) "fused aluminum oxide", 2) "fused white aluminum oxide", 3) "calcined aluminum oxide", or 4) an "alumina" of some type. Fused aluminum oxide is the one that is a common abrasive and is usually dark colored. Fused white aluminum oxide is a white Al2O3 that is also an abrasive that is purified, but is less common and more expensive. Calcined aluminum oxide or alumina usually implies a material with a higher alumina content and which has been processed at higher temperatures (calcined).
In the real world vernacular, "aluminum oxide" will usually refer to the dark brown to black Al2O3 abrasive (fused aluminum oxide). The term "alumina" will usually refer to the white Al2O3 that is not an abrasive and is associated with refractory or other ceramic applications where high physical properties are required. The latter term has the most variations. You will see it as just "alumina", "alumina oxide", "calcined alumina", "calcined alumina oxide", "calcined aluminum oxide", and possibly others. Adding to the confusion of which "Al2O3, aluminum oxide" you're dealing with, is the fact that the above terminology can vary by manufacturer and meanings can be mixed depending on who is describing a type of Al2O3, and what it's been used for in the past.
There are several names for "Fused aluminum oxide" that differ from appearance and place to place. There is a "Brown Fused Alumina" and a "Black (Fused) Aluminum Oxide", and also an "Artificial Corundum", and of course "Fused alumina oxide".
The abrasive Al2O3 "Fused aluminum oxide" is made by mixing it with iron in an electric arc furnace and taking it to very high temperatures. It comes out a brown/black color and is crushed to make tough (fused) "aluminum oxide" abrasive particles.

The Digital Fire ceramics resource says this about alumina { https://digitalfire.com/4sight/material/alumina_40.html } :
"Alumina (properly called aluminum oxide) powder as used in ceramics can be a white granular material (like table salt) or an exceptionally fine silky white and dense powder...
Alumina oxide ceramics have very high melting temperatures and hot and cold mechanical strength and are good for abrasion and corrosion resistant applications where heat resistance is also important (compressive strength may average 250,000 psi but high purity mixes can be up to 500,000 psi!). They are among the strongest, hardest and most abrasion resistant of all ceramic materials. The strength of alumina ceramics is exceeded only by silicon carbide, boron carbide and diamond; the abrasion resistance only by diamond. They also have outstanding electrical and thermal properties (like high dielectric strength, high electrical resistance, low dielectric loss). Spark plugs, for example, are made using a high alumina porcelain (about 90%) for its insulating properties coupled with its strength, heat and thermal shock resistance. High alumina ceramics (99%+) can provide such good resistance to chemical attack that they can resist hydrofluoric acid and molten alkalis and alkali vapors. The chemical inertness of these same bodies make them ideal for making valves and seals exposed to severe corrosive and abrasive conditions. Alumina ceramics also resist the effects of radiation that can destroy other materials. Further, alumina ceramics maintain most of the above properties at elevated temperatures. Many of alumina's outstanding properties can be further enhanced by specific manufacturing methods and additives.
Since alumina is by nature refractory, alumina ceramics and alumina refractories might seem like redundant terms. However the former refers to alumina containing bodies that have a fine grain structure and dense matrix and whose purpose is more than just resistance to temperature. The term 'high alumina ceramics' generally refers to mixes containing 85+% alumina. Some high demand applications such as furnace tubes and labware cross the boundaries of both alumina ceramics and alumina refractories, these are often made from 99.8% alumina mixes. 99.9% aluminas are used in super duty applications like nuclear ceramics and cutting tools...High alumina bodies lack forming properties so organic and inorganic lubricants, binders, electrolytes and plasticizers are used.
While greater quantities of alumina often improve the properties of mixes in which they are being used alumina is expensive and greater quantities require higher firing. Thus a compromise between performance and cost must be reached.
The mineral corundum yields native alumina while the hydrated minerals gibbsite, diaspore, and boehmite are also found in nature. Alumina occurs as silicates in clays, feldspars, kyanite, and many other minerals. However, the principle sources of purified and hydrate alumina are native bauxite and laterite deposits."-
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Reviews

Reviews (5)

Average:

Jul 11, 2022

Thank you so much! Lightning fast delivery and expertly packaged!

Dean Schmidt

Mar 18, 2022

Kayden

Nov 16, 2021

Its pure 👍🏻 not sure what else to say… itll do what i need it for

Ty

Mar 13, 2021

Excellent product. Worked very well for home made rubies.

cchristopher01

May 12, 2020

Thank you, as shown and work well :)

Amy Longwell