Ceramic and Glass Materials

2 R.H. Doremus

and cutting tools. The electrical resistance of alumina is high, so it is used pure and

as a component in electrical insulators and components. Alumina has excellent

optical transparency, and along with additives such as chromium and titanium, it

is important as a gem stone (sapphires and rubies) and a laser host (ruby). Because

of its high melting temperature, chemical inertness, and optical transparency, it is

highly useful for containing arcs in street lamps. See Table 1 and also [1, 2] for

more on uses of alumina.

In this review, the processing of alumina is discussed next, and then its properties

are tabulated and described. In a summary future uses of alumina are considered.

2 Processing

2.1 Raw Materials

Bauxite is the name of the ore that is the primary source of alumina; bauxite contains
gibbsite,γ-Al(OH) 3 , which is the stable phase of Al(OH) 3 at ambient temperature and
pressure. The structure of alumina and hydrated alumina phases are listed in Table 2.

Table 1Uses of Alumina

Solid alumina

Furnace components

Catalyst substrates

Electronics substrates

Electrical insulators

Cutting tools

Bearings

Spark Plugs

Arc lamp tubes

Laser hosts

Gem stones

Alumina powders

Abrasives

Catalyst pellets

Alumina coatings

Oxidation protection of aluminum

and aluminum alloys

Capacitors

Transisitors

Bioceramics

Alumina fibers

Thermal insulators

Fire retardation

Alumina as a component of

Ceramics and glasses

Mullite components

Electrical insulators

Porcelains

Durable glasses