Impact of spinel forming systems (Fe-/Mg-/Mn-Al-O) as functional coating materials for carbon-bonded alumina filters on steel melt filtration

Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel melts. In order to attain a significant improvement of the filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400?°C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest filtration efficiencies.