Zirconium Oxide (ZrO₂)
Unlike other ceramic materials, zirconium oxide (ZrO2 –also known as zirconia) is a material with very high resistance to crack propagation. Zirconium oxide ceramics also have very high thermal expansion and are therefore often the material of choice for joining ceramics and steel.
Another outstanding property combination is the very low thermal conductivity and high strength. In addition, some types of zirconium oxide ceramics can conduct oxygen ions. Components made from this material are significantly more expensive than components made of alumina ceramics.
Application Examples
Due to their biocompatibility, zirconium oxide ceramics are used, for example, as a material for crowns and bridges in the dental industry, as tools for wire forming, as an aid in welding processes, as technical cutters in the textile industry, as an insulating ring in thermal processes and as an oxygen measuring cell in lambda sensors. Other fields of application include electronics, aviation and energy generation, where zirconium oxide is used as an insulator and in high-performance components.
In the future, the material could play a key role in environmental and energy technology, e.g. in fuel cells, which rely on durable and stable materials.
Main Properties of Zirconium Oxide (ZrO₂)
- High thermal expansion (α=11 x 10-6/K, similar to some types of steel)
- Excellent thermal insulation/low thermal conductivity (2.5 to 3 W/mK)
- Very high resistance to crack propagation, high fracture toughness (6.5 to 8 MPam1/2)
- Ability to conduct oxygen ions (used for the measurement of oxygen partial pressures in lambda probes)
Properties and Key Improvements of HTZ500
| Property | ZN40 | MZ429 | HTZ500 |
| Sintering | DB | DB / HIP | DB / HIP |
| Density | 5,79 g/cm3 | 6,06 / 6,07 g/cm3 | 5,95 / 5,96 g/cm3 |
| Zirconia grain size | 35 µm | 0,4 / 0,3 µm | - / 0,5 µm |
| Monoclinic phase content | 3% | ≤ 1% | ≤ 1% |
| Young modulus (GPa) | 210 | 220 | 220 |
| Hardness HV1 (GPa) | 11 | 13 | 13 |
| Toughness K1c (IFR) | n.a. | 5 MPa·√m | 12 MPa·√m |
| Bending strength (4PB) | 500 MPa | 1000 / 1500 MPa | 1000 / 1720 MPa |
| Weibull | 20 | 20 / 10 | 20 / 10 |
| Accelerated aging1 | - | 15% | 13% |
| Thermal expansion coefficient | 10,2 * 10-6·K-1 | 10,5 * 10-6·K-1 | 10,6 * 10-6·K-1 |
| Thermal conductivity (W/m·K) | 3,0 | 3,0 | 3,6 |
1 Monoclinic phase content after 10 h in autoclave at 134 °C and 2 bar
Where HTZ500 outperforms common ZrO₂ Materials
- Very high strength and reliability
- Damage tolerance and fracture toughness (3x higher than standard zirconia, 4x higher than ATZ, 5x higher than standard alumina)
- Increased cutting edge stability
- Grinding resistance, shorter processing times, reduced tool wear, less damage
- Aging resistance (stability under hydrothermal conditions)
- Meets the requirements of ISO 13356
- Strength is more than twice the value required by the standard
