Users and manufacturers are always interested in improving the quality of casted metallic products. Producing high quality and zero defect materials demands an improvement in the degree of purity of casted metals. Therefore a remarkable reduction of inorganic nonmetallic inclusions (such as ceramics) in the melt is necessary. Filtration of the metals can be a method to achieve these high quality demands.
The researchers of the Collaborative Research Center 920, funded by the Deutsche Forschungsgemeinschaft (DFG), at the Technische Universität Bergakademie Freiberg, Germany, are developing new filter materials and studying their effectiveness.
One point of interest is the interaction of the metal melt, e.g. an aluminum alloy, with novel filter materials. Therefore, the wettability and potential chemical reactions between four different filter materials and an aluminum alloy were investigated. The filter materials consisted of oxide ceramics. The picture shows images of aluminum alloy droplets on the different filter materials at the end of the wetting experiments for the measurement of contact angles. The dimension of the contact angles indicates the kind of the wettability.
It could be proven that in three cases, a reaction between the metal and the filter material took place during the tests, and reaction layers consisting of aluminum and oxygen were formed. It can be concluded that in case of the investigated filter materials, the chemistry of the filters influenced the wetting process, while the final values of the contact angles were more influenced by the roughness of the reaction layers formed.
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