Magnesium Filtration with Ceramic Foam Filters and Subsequent Quantitative Microscopy of the Filters

Magnesium alloy AZ91 melts have been filtered through ceramic foam filters in laboratory scale experiments. Inclusion contents in the melts were adjusted by adding fractions of return die cast metal. During the experiments metal flow and metal temperatures were logged. The results show that the transition from depth to cake filtration is quite pronounced. This indicates that depth filtration and cake filtration act in sequence. Some of the filters have been sliced in the flow direction and analyzed for oxide inclusions employing automatic image analysis. The results from the metallographic examinations indicated that the filtration efficiency of the ceramic foam filters was very good. However, the filter life might be considered unacceptable.