Zirconia
Properties:
Zirconia is an extremely refractory material. It offers
chemical and corrosion inertness to temperatures well above the melting point
of alumina. The material has low thermal conductivity. It is electrically
conductive above 600°C and is
used in oxygen sensor cells and as the susceptor (heater) in high temperature
induction furnaces. With the attachment of platinum leads, nernst glowers used
in spectrometers can be made as a light emitting filament which operates in
air.
Key
Properties of Zirconium Oxide
1.Use
temperatures up to 2400°C
2.High
density
3.Low
thermal conductivity (20% that of alumina)
4.Chemical
inertness
5.Resistance
to molten metals
6.Ionic
electrical conduction
7.Wear
resistance
8.High
fracture toughness
9.High
hardness
Application:
1.The
most important zirconium compound, the zircon, is used as refractory material
for mould-casting, as abrasive and as constituent of insulating
materials, enamels and other resistant to the temperature materials.
2.It
is also used as an artificial semi-precious stone, imitating diamond. Zirconium
oxide is used as refractory material in the production of piezoelectric
crystals and rings of high frequency induction reels, due to its low resistance
to high temperature.
3.It
is still used as pigment in the ceramic industry. More than 80% of the produced
zirconium is consumed in the form of these two compounds.
4.Other
zirconium compounds have interesting properties and important applications.
Thus, the carbide and the nitride with their high hardness, are used in
producing abrasives and sharp edged instruments; the hydride is an hydrogen
source and can be used as moderator in nuclear reactors; the double ammonium
carbide and zirconile are used in preparing hydrophobic fluids and water-proof
coatings; the phosphate, the molybdate and the tungstate are used as ion
permuters, especially selective for alkali metals.
5.Metallic
zirconium is the best construction material for nuclear reactors due to its low
neutron cross section, high mechanical and chemical resistance and appropriate
thermal conductivity.
6.It
is also used in the manufacture of zircaloy alloys that contain tin, iron and
chromium in small amounts. Other smaller applications include flash production
for photography, explosive, fireworks, tracer bullets, small rockets, etc.
