Editorial Feature

Zirconia - Physical and Mechanical Property Comparison of the Different Types of Zirconias

Zirconias, when partially stabilized with either Yttria or Magnesia, exhibit excellent mechanical properties at high temperatures and are relatively inert to adverse environments.

They are used in refractory applications, thanks to their good thermal shock and impact resistance. Since zirconias are resistant to attack by most molten metals, they are often used as crucible materials.

Their excellent hardness and wear resistance make them suitable for high temperature nozzles and extrusion dies. At higher temperatures, zirconias become conducting and are therefore used as heating elements. They also find application as thermal barrier coatings for gas turbine blades.

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. These have evolved as researchers and manufacturers sought to exploit the different properties of the various phases. Some of the phases are stable at high temperatures and need to be “frozen” in such that they can be used at room temperatures, while others exploit toughening mechanisms that are only found in these and few other materials. Some of these materials are listed below along with their typical abbreviations.

Table 1. The different types of zirconias.

Material Abbrev.
Tetragonal Zirconia Polycrystals TZP
Partially Stabilised Zirconia PSZ
Fully Stabilised Zirconia FSZ
Transformation Toughened Ceramics TTC
Zirconia Toughened Alumina ZTA
Transformation Toughened Zirconia TTZ

 

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 Al 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 2. lists properties for various grades of zirconia and has been compiled from a variety of sources. 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

Primary author AZoM.com

Comments

  1. Kelly Loyd Kelly Loyd United States says:

    You speak about the different types of Zir. The Zirc Product by Nobel which uses a slurry of zirconia oxide upon an over sized die, is the same process as an In-Ceram? Also what properties are Procera restorations  made from: Ce-TZP, ZTA, Mg-PSZ or 3Y2OA?
    thx kel

    • Ryan izcool Ryan izcool Canada says:

      hey kelly hope you found what you're looking for!!!!!!

  2. Smita Pandey Smita Pandey India says:

    what is modulus of elastisity of monoclinic zirconia

    • Ryan izcool Ryan izcool Canada says:

      Smita your question is beutiful and amazing, just like you! keep up the good work buddy
      love ryan

  3. Ryan izcool Ryan izcool Canada says:

    Pretty good table. Lots of goofs and gavs

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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