Zirconia Ceramic Insert For Tundish Upper Nozzle

Zirconia has a melting point as high as 2,700°C and exhibits exceptional chemical stability at high temperatures. It can withstand long-term corrosion and high-speed erosion from molten steel and slag, with a corrosion rate of ≤0.5 mm/h. Compared to standard high-alumina nozzles, its service life is 2–3 times longer, allowing for stable operation for over 12 hours per pour and reducing the frequency of shutdowns for replacement.

Designed with a low coefficient of thermal expansion and a stabilized crystalline structure, it can withstand ≥30 thermal shock cycles from 1100°C to room temperature. It exhibits no spalling or cracking during casting start-ups, shutdowns, or temperature fluctuations, making it suitable for complex operating conditions such as cold starts and frequent steel grade changes.

The precision streamlined design of the inner cavity, combined with multi-stage stepped flow channels, reduces turbulence in the molten steel. This ensures a constant, fluctuation-free flow, lowering the secondary oxidation rate to below 0.8%. This reduces the formation of inclusions, significantly improves the surface finish and internal density of the ingot, and minimizes defects such as cracks and shrinkage cavities, meeting the demands of high-end steel production.

The high-purity zirconia material does not react with molten steel, eliminating issues with slag adhesion and buildup. The orifice diameter remains stable over extended use, preventing nozzle blockages. Compatible with various flow control systems-including stopper rods and orifice adjusters-it supports custom orifice sizes (φ10mm–φ50mm) to accommodate different steel grades and continuous casting speeds.

The cement-free composite structure ensures a tight bond between the insert and the outer layer, eliminating the risk of molten steel leakage and preventing production accidents. Its long service life reduces spare part consumption and downtime losses, while stable billet quality lowers scrap rates, comprehensively helping enterprises reduce costs and improve efficiency.