Zirconia
Zirconia Ceramics are a group of technical ceramics that include Cubic Zirconia (ZrO2), Partially Stabilized Zirconia (PSZ) and Tetragonal Zirconia Polycrystal (TZP) that are broadly defined by their high thermal shock resistance. By combing Zirconia with other materials it is possible to increase their toughness and surface finish capabilities.
Cubic Zirconia (ZrO2): Cubic Zirconia is a technical ceramic that is optically clear with low fracture toughness and strength but a very high thermal shock resistance. It has a fine grain size meaning it can provide an excellent surface finish and hold a sharp edge.
Partially Stabilized Zirconia (PSZ): Partially Stabilized Zirconia is Zirconia blended with approximately 10% MgO. It is cream coloured, high in toughness and is able to retain this property at elevated temperatures. PSZ is typically somewhat lower in cost than ZrO2 but also features a larger grain structure.
Tetragonal Zirconia Polycrystal (TZP): Zirconia blended with approximately 3% Yttria are called Tetragonal Zirconia Polycrystal (TZP). They exhibit the highest toughness at room temperature, due to their tetragonal structure, however this degrades severely between 200 and 500 °C. TZP also have the finest grain size.
Zirconia applications:
- Turbocharger components
- Ball bearings
- Cutting tools
- Advanced ceramic tubes
- Valve components
- Nozzles
- Seals, seats and bearings
Property | Cubic Zirconia | PSZ | TZP |
---|---|---|---|
General |
|||
Chemical Formula | ZrO2 | ZrO2-MgO | ZrO2-Y2O3 |
Mechanical |
|||
Density | 5.92 g/cm3 | 5.75 g/cm3 | 6.04 g/cm3 |
Hardness | 7.5 Mohs | 1120 - 1300 Knoop | 1300 - 1600 Knoop |
Modulus of Elasticity | 15 - 30 x 106 psi | 29 - 30 x 106 psi | 29 - 30 x 106 psi |
Flexural Strength | 100 kpsi | 100 kpsi | 130 - 150 kpsi |
Compressive Strength | 174 - 600 kpsi | 268 kpsi | 360 - 700 kpsi |
Poisson's Ratio | 0.22 - 0.32 | 0.23 - 0.31 | 0.23 - 0.32 |
Fracture Toughness | 1 - 8 MPa m1/2 | 12 MPa m1/2 | 7 - 13 MPa m1/2 |
Electrical |
|||
Dielectric Strength | 50 ac V/mil | ||
Dielectric Constant | 20 (@ 1 MHz) | 26.0 (@ 1 MHz) |