Research On Properties Of Different Matrix Bonded Purging Plug Materials For Steel Ladle

Purging plug is the major component in the ladle refining argon blowing process.Because of the harsh using condition, it has short lifespan, and affects the lifespan of wholerefractoriness of the ladle.The materials need have both large high temperature strength andgood thermal shock resistance. It is the difficulty and key point of related research. In thispaper, we investigated the effects of the different matrixes composition on cold physicalproperties, high temperature strength and thermal shock resistance of materials thoughadjusting magnesite content and particle size, useing magnesia binder, added TiO₂andnon-oxide to optimize the matrix composition of the materials. Concluded that:（1） Al₂O₃-MgO-Cr₂O₃castables combined by magnesia binder are good at thermal shock resistance,but both the cold intensity of the non-firing castables and HMOR of the castables after sintering were toolow. It would not meet the purging plug application requirementsThe castables were prepared by using tabular corundum, fused white corundum powder,α-Al₂O₃powder, MgO micro-powder, Cr₂O₃micro-powder and Secar71calcium aluminatecement as the main raw materials. It has large bulk density, cold and high temperaturestrength after sintering at1600℃; but thermal shock resistance of materials is general. Thecastables were the most appropriate which the amount of magnesia was about2wt%-3wt%.The bulk density, cold and high temperature strength of the castables are increased byadding fine grinding of fused magnesia. The properties of the material was relatively goodwhich magnesia grain size was10μm or15μm.The spinel through the reaction between finegrinding of magnesia and alumina distributed more evenly in matrix. This reduces the RLC ofthe materials after burning effectively; but there is no obvious improvement in thermal shockresistance of materials.The Addition of TiO₂into the castables, which could promote the sintering, increases thestrength and bulk density of materials significantly. Al₂TiO₅with ultra-low thermal expansioncoefficient which was generated in situ at high temperature improves the thermal shockresistance of materials effectively. The castables which added6wt%TiO₂would have the bestperformance on thermal shock resistance and high temperature strength.（2） The materials would have good performance which were prepared by using tabularcorundum, Al₂O₃powder, fused magnesite and metal aluminum powder as the main rawmaterials, phenolic resin as the binder，was compressed though plastic molding，and sinteredat high temperature in nitrogen atmosphere. When adding2wt%magnesite and10wt%Alpowders, properties of the materials would be best. Compared with aluminum-magnesium（chrome） castables in the previous chapter, the materials made by this method would haveobvious advantages in HMOR and thermal shock resistance. Beside these，non-oxide has thecharacteristics of not wetting with the steel. It has a positive effect on solving the problem ofstoppage of purging plug caused by liquid steel seeping into the slits. The materials have thepotentials in applying to purging plug.