Ceramic Foam Filters (CFF) are widely used in metal melt filtration to obtain high-quality casting products. These filters are characterized by their highly porous, open-cell structures and good mechanical, chemical and thermal stability. The permeability of the filters is a critical parameter because it offers insight into flow characteristics through the filter, which in turn contributes to optimizing filter design, selecting suitable pore sizes, and maintaining consistent metal flow rates during casting. Several correlations for calculating the permeability can be found in the literature. However, these differ greatly in both form and resulting permeability values. In most cases, one or more fitting parameters are used to fit the equation to the data. This results in a lack of transferability to new filters. Comparisons between different equations show large deviations of up to 600% [1]. The reason for this is that the structural properties of the filters vary considerably between different suppliers, even for filters with the same nominal pore size [2]. In addition, the morphological and hydraulic parameters are not uniformly defined or measured across studies, highlighting the need for a systematic approach towards characterizing CFFs.

The present work shows that it is possible to predict the permeability of ceramic foam filters without needing correlations specifically designed for CFFs. Instead, the key to accurately estimating permeability is the precise determination of the structural characteristics of the filters, such as pore size, shape, porosity, and tortuosity. To achieve this, the structural parameters of 10 and 30 ppi filters were investigated using µ-CT measurements. As pore size appears to be the most critical parameter, different equivalent pore size diameters are compared. Experimental permeability values obtained from pressure drop measurements at varying flow rates are used to validate the calculated permeabilities...