Microstructure and properties of ceramic filter containing porous MgO coating and its filtration of Al2O3 inclusions in molten steel

Reticulated ceramic filters can be used to remove non-metallic inclusions in molten steel and improve the quality of steel products. In this work, three kinds of new reticulated ceramic filters were prepared by using spinel (MgAl2O4), ZrO2 and SiC reticulated ceramic filters as preforms, respectively, which were all coated with porous MgO coating on their surfaces. The effect of preform type on the phase composition, microstructures, mechanical properties and interaction with molten steel of the filters was studied. The results show that the filter fabricated by spinel preform exhibited the best mechanical properties, which related to the formation of better interface bonding between the spinel preform and the porous MgO coating. Compared with the filters containing ZrO2 and SiC preforms, the porous MgO coating on the surface of the filter containing spinel preform had the highest roughness, which significantly improved the contact area between the filter and the Al2O3 inclusions, thus promoting the adsorption capacity on Al2O3 inclusions. Overall, the filter with spinel preform had the highest cold compressive strength of 0.86 MPa and flexural strength of 0.96 MPa, excellent thermal shock resistance against to molten steel, as well as the best adsorption capacity on Al2O3 inclusions.