What causes damage to zirconia nozzles?
Oct 25, 2025
Zirconia nozzles are a common type of tundish nozzle. Made from high-temperature–resistant zirconia, they can withstand molten steel without easily suffering damage. However, continuous steel casting is a complex process - even a high-performance zirconia nozzle may be damaged if casting operations are not properly controlled. The main causes of zirconia nozzle damage can be divided into physical damage and chemical damage.
Physical Damage
Thermal Shock Damage:
During the steel casting process, zirconia nozzles are exposed to high temperatures and rapid heating. Uneven internal temperature distribution subjects the nozzle to severe thermal shock. This structural stress reduces the nozzle's strength and erosion resistance, making it easier for molten steel and slag to penetrate and corrode the material.
Mechanical Erosion Damage:
The mechanical erosion caused by molten steel flow is also a major factor. Although molten steel is viscous, its high density, temperature, and velocity create strong thermal and mechanical impacts on the nozzle wall. The resulting temperature gradient across the nozzle section weakens the wall strength where it contacts the steel.
Chemical Damage
Zirconia Dissolution:
The main chemical composition of a zirconia nozzle is ZrO₂ with small amounts of stabilizers (CaO, MgO, Y₂O₃, etc.) and trace impurities. Pure zirconia undergoes a martensitic phase transformation between the monoclinic and tetragonal crystal phases at 900–1200 °C, which causes volume changes and makes it impossible to produce pure zirconia products.
In addition to zirconia nozzles, there are many other types of nozzles, such as measuring nozzles and quick-change measuring nozzles. To improve casting efficiency, quick-change nozzle technology has also been widely adopted.
Depending on the specific casting conditions, the specifications and types of zirconia nozzles used will vary to ensure optimal performance.
Our company supplies various types of zirconia nozzles.
If you are interested in purchasing high-temperature zirconia products, please email us at zhang@ayctgy.com. We will reply to your inquiry as soon as possible.
