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Material Specification

Zirconia

Background

The fundamental properties of zirconia ceramics which are of interest to the engineer or designer are:

High strength

  • High fracture toughness
  • High hardness
  • Wear resistance
  • Good frictional behaviour
  • Non-magnetic
  • Electrical insulation
  • Low thermal conductivity
  • Corrosion resistance in acids and alkalis
  • Modulus of elasticity similar to steel
  • Coefficient of thermal expansion similar to iron.

    • Types of Zirconias

    There are many different types of zirconias. Some of these materials are listed below along with their typical abbreviations.

    Table 1. The different types of zirconias.

    Material

    Abbrev.

    Partially Stabilised Zirconia

    PSZ

    Fully Stabilised Zirconia

    FSZ

    Alumina Toughened Zirconia

    ATZ

    Zirconia Toughened Alumina

    ZTA

    Materials (oxides) added to stabilise or toughen the zirconia will also be noted as a prefix to the abbreviations listed in table 1. They will sometimes be used in conjunction with numbers which indicate the amount of the stabilising agent added. Typical examples include Y, Ce, Mg and A which correspond to yttria (Y2O3), ceria (CeO2), magnesia (MgO) and alumina (Al2O3) respectively. So a material denoted as 3Y-TZP would tetragonal zirconia polycrystal with an addition of 3mol% Y2O3 as a stabiliser.

    Property Comparison

    Table lists properties for various grades of zirconia and has been compiled from a variety of tests. However, as with most ceramic materials properties are dependent on many factors such as starting powders and fabrication techniques. Most ceramic fabrication techniques have been applied to zirconias such as dry pressing, isostatic pressing, injection moulding, extrusion and tape casting. Addition of impurities during processing may also introduce flaws and degrade properties.

    Table 2. Typical properties of various types of zirconia.

    Property

    Y-TZP

    Ce-TZP

    ZTA

    Mg-PSZ

    3Y20A

    Density (g.cm-3)

    6.05

    6.15

    4.15

    5.75

    5.51

    Hardenss (HV30)

    1350

    900

    1600

    1020

    1470

    Bend Str. (MPa)

    1000

    350

    500

    800

    2400

    Compressive Str. (MPa)

    2000

    -

    -

    2000

    -

    Young’s Modulus (GPa)

    205

    215

    380

    205

    260

    Poisson’s Ratio

    0.3

    -

    -

    0.23

    -

    Fracture Toughness (MPa.m-1/2)

    9.5

    15-20

    4-5

    8-15

    6

    Thermal Exp. Co-Eff (x10-6 °C-1)

    10

    8

    8

    10

    9.4

    Thermal Conductivity (W.m-1.K-1)

    2

    2

    23

    1.8

    3

    Material Specifications

    Material Specifications

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