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There exists an increasing pressure on the metal-making and metal-using industry to remove solid and liquid inclusions such as deoxidation products (oxides), sulfides, nitrides carbides, etc. and thereby improve metal cleanliness. It is well known that size, type, and distribution of non-metallic inclusions in metal decrease dramatically the mechanical properties and especially the fracture toughness, the tensile strength, the ductility as well as the fatigue of the cast products resulting to excessive casting repairs or rejected castings. [1] In case of the oxide inclusions in steel melts, Wasai et al. [2] assigned the dendritic, maple-like and polygonal inclusions to the group of the primary inclusions generated directly after adding aluminum in the metal melt. In contrast, the network-like, coral-like, and spherical inclusions, which are composed of alumina, hercynite, and wü stite, are classified as secondary inclusions. The secondary inclusions are formed due to the lower solubility of oxygen in the melt as a function of the temperature above the liquidus temperature of the melt. In case of the secondary inclusions, the a-, g-, and d-alumina modification are more frequently detected in steel melts. Below the liquidus temperature tertiary and quartenary inclusions are generated that present the highest impact on fractures toughness of steel casts according to Ovtchinnikov. [3]

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Surface functionalized carbon bonded foam filters have been evaluated with the aid of an industrial steel melt according to their performance to filtrate non-metallic inclusions. Exogenous alumina based nonmetallic inclusions have been introduced in the steel melt in order to distinguish the influence of the filter surface chemistry on the deposition of non-metallic inclusions. The used filters have been examined after casting according to the population and chemistry of the deposited inclusions. Based on the deposition results an alumina coating leads to the highest deposition of alumina inclusions.

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