Alumina as an Important Ceramic Material

Aluminium oxide is a chemical compound of aluminium and oxygen.  It has  the chemical formula Al2O3. It is the most commonly occurring oxide of  aluminium. It is commonly called alumina, however, the other names are aloxite, aloxide and alundum depending the function.

It occurs naturally in its crystalline polymorphic form. It is known as corundum which form several varities of precious gemstones sapphire and rubies. It is major use is in the production of aluminium metal. Due to its hardness it is also used as an abrasive material.

Natural occurrence

Its most common naturally occurring crystalline form is Corundum. Corundum forms Rubies and sapphires are gem stones. Its characteristic color is due to the presence of trace impurities. Rubies possess characteristic deep red color by the presence of traces of chromium.

Sapphires come in different colors due to the impurities of iron and titanium. It is also a good refractory material due to its good high melting point.

Essential Properties of Alumina Ceramic:

• Al2O3 is a very good electrical insulator.
• It has a relatively high thermal conductivity for a ceramic material.
• Its hardness makes it suitable for the use as an abrasive.
• It is an important component of cutting tools in machining industry.
• Machining Alumina Ceramic is done for making diamond cutting tools.
• Aluminium oxide is resistant to to weathering.
• Metallic aluminium is very reactive with atmospheric oxygen.
• It shows the properties of corrosion and wear resistance.
• The aluminium oxide generated by anodising is typically amorphous.

Industrial Application of Aluminium Oxide:

The Hall–Héroult process is used for over 90% of the production of aluminium. Ceramic Alumina is used in a wide variety of applications due to  its inertness, temperature resistance and electrical resistance.  Few of the most important industrial application have been mentioned Below:  

1. Filler Material in Industry:

Alumina is chemically inert and white in color. Due to these properties, aluminium oxide is a favored filler for plastic and other industries. It is a common ingredient in sunscreen in the cosmetic industry.  Face blush, lipstick, and nail polish at times also contain Alumina oxide in minimal quantities.

1. Glass Industry:

Many formulations of glass and silica have Al2O3 as an important ingredient.

1. Paint

Aluminium oxide flakes are used in paint for reflective decorative effects.

1. Catalysis

It catalyses a variety of reactions. In its largest scale application, as a catalyst in the Claus process used in refineries. It is for dehydration of alcohols to alkenes. Aluminium oxide serves as catalysis in well known Ziegler-Natta reaction for the polymerization of metals.

1. Abrasive:

Aluminium oxide has a great hardness and strength; therefore it is widely used as an abrasive ceramic material. Machining Ceramic is done as a less expensive substitute for industrial diamond.