Calcium Aluminate Reactive Coatings on Carbon‐Bonded Alumina Filters for Clean Steel Approaches

New carbon‐bonded filters with coatings based on calcium aluminates are developed. The samples are tested for 10 s in contact with a steel melt containing endogenous inclusions at 1650 °C, in order to explore the behavior and impact of these materials on the filtration process. Investigation of the filters after the test is carried out by optical and scanning electron microscopy. In addition, steel samples are analyzed with a special automatic SEM. The population of the detected inclusions is classified in terms of size and chemistry. Both compositions deliver excellent filtration results. Carbon‐bonded alumina filters coated with calcium aluminates are immersed into molten steel at 1650 °C. After 10 s, a thin secondary layer and polyhedral particles containing Ca, Al, and O are found on both samples. In addition, fine endogenous inclusions are collected. The steel analysis after the immersion test indicates that both compositions can deliver excellent filtration efficiencies.