China's Refractories

Abstract: The development of refractories with low reactivity to rare earth inclusions is an important direction to solve the problem of the nozzle clogging of rare earth steel. La₂Ce₂O₇, La₂Zr₂O₇, and LaAlO₃ powders were synthesized using the high-temperature solid-state method with La₂O₃, CeO₂, ZrO₂, and Al₂O₃ (particle sizes of 5-10 μm) as raw materials, firing at 1 400 °C for 2 h. Subsequently, La₂Ce₂O₇, La₂Zr₂O₇, and Y₂O₃ powders were pressed into φ30 mm×7 mm substrate samples with PVA as a binder; and equal amounts of La₂O₃, La₂S₃, and LaAlO₃ powders were placed on their surfaces. The samples were then fired at 1 550 °C for 3 h with carbon embedded. The interfacial reaction of the three rare earth oxide refractories (La₂Ce₂O₇, La₂Zr₂O₇, and Y₂O₃) with the main rare earth inclusions (La₂O₃, La₂S₃, and LaAlO₃) in molten rare earth steel was studied. The results show that the La₂Ce₂O₇ sample has poor structural stability and readily reacts with La₂S₃, leading to cracking. The La₂Zr₂O₇ sample reacts with La₂O₃ and LaAlO₃ weakly, but performs poor La₂S₃ corrosion resistance. The Y₂O₃ sample demonstrates the weakest interaction with the three rare earth inclusions as well as the most stable structure, indicating significant potential as a specialized anti-clogging lining material for rare earth steel.

Key words: rare earth oxides, anti-clogging linings, submerged entry nozzles, interfacial reaction