Preparation of resin coated alumina aggregate and its effect on the properties of alumina-spinel castables for purging plugs

Abstract

Secondary refining processes were indispensable for high-quality steel in the modern steelmaking process, and refining processes in ladles were necessarily performed by argon bubbling through purging plugs, therefore properties and service life of purging plugs were directly impacted on the production efficiency and cleanliness of steel products. To date, purging plugs with slots have been widely used in steel ladles because of their higher strength, stable permeability and higher service lifes. However, poor thermal shock resistance limited their application and enhancement of service life, it is of great significance to improve their thermal shock resistance. In this manuscript, coated aggregates were prepared by coating with phenolic resin on tabular alumina aggregates, and effect of coated aggregates on the properties of alumina-spinel castable was studied. The results show that apparent porosity and permanent linear change rate increase, cold strength and hot strength decrease, and residual strength ratio markedly increase with rising of coating layer thickness of the aggregates, indicating that thermal shock resistance of the sample is significantly improved. The improvement mechanism in the thermal shock resistance of the castables was also discussed in details. The alumina-spinel castables containing microspaces with enhanced thermal shock resistance can be utilized to fabricate longeval purging plug materials for steel ladles.