Overview of the Possibilities and Limitations of the Characterization of Ceramic Foam Filters for Metal Melt Filtration

Abstract

The filtration of molten metal using ceramic foam filters (CFF) is a purification method often used by the aluminum industry to meet the increasing demands the melt quality. CFFs are in most cases produced by the replica method using polyurethane foam templates, which are coated with a ceramic slurry of targeted composition before being sintered into its final structure. Despite the key role of CFFs in view of metal cleanliness, there are only a few quality parameters for their evaluation. In the present study, an overview of the different material properties essential for CFFs, suitable measurement methods, and their limitations are presented. The focuses of this work are the different densities of ceramic foams and the thermal expansion coefficient measured by dilatometry, as well as the filter porosities and microstructure measured through mercury intrusion porosimetry and computer tomography, respectively. Moreover, elastic (Young’s Modulus) and mechanical properties (compressive strength) are discussed.