Aluminum oxide

Aluminum oxide (CAS number 1344-28-1) has the chemical formula Al₂O₃. It is a
common white powder widely used as an abrasive, catalyst, and refractory
material, and exists in various forms (such as activated alumina).
Both rubies and sapphires are primarily composed of aluminum oxide, but their
different colors are due to other impurities. Rubies are red because they
contain chromium oxide, while sapphires are blue because they contain iron
oxide and titanium dioxide.

Aluminum oxide is what makes metallic aluminum resistant to corrosion in air.
Pure metallic aluminum readily reacts with oxygen in the air, forming a thin
film of aluminum oxide covering the exposed aluminum surface. This film
prevents further oxidation of the aluminum. The thickness and properties of
this oxide film can be enhanced through a process called anodizing (anodic
corrosion protection).

Aluminum is a good conductor of electricity and heat, while aluminum oxide is
an insulator of both. The crystalline form of aluminum oxide, corundum, is
suitable for use as an abrasive material and cutting tool due to its high
hardness.

Crystals of aluminum oxide can also be used as a substrate for epitaxy.

Aluminum oxide powder is commonly used as a medium in chromatography.

In August 2004, scientists at 3M in the United States developed a reinforced
glass called transparent alumina, created from an alloy synthesized from
aluminum and rare earth elements.

It can be used in emergency braking systems for high-speed trains (by spraying
alumina powder onto the rails to increase friction). Porous alumina with a high
surface area ratio is called activated alumina and is commonly used as a
catalyst, adsorbent, dehydrating agent, and catalyst carrier. A typical
application is as a catalyst in the Claus reaction.

It is a major component of refractory bricks.

Minimum Order: 1 short tons