Inclusion removal using ceramic foam filtration in the casting industry is well known, however the effect of ceramic foam filters on removing inclusions from 'clean' metal is not so well documented. This communication provides a preliminary report of the findings to date. Ceramic foam filters have been used in the production of approximately 3.3 tonne casts using the new VIDP furnace at Special Melted Products Ltd. Clean metal is supplied by the use of a specially designed launder system preheated to 900°C prior to teeming.
Examination of impregnated filter cross sections from an alloy 718 and FV458 casts have revealed the ability of ceramic foam filters to remove inclusions in the <20 μm size range.
The types of inclusion that are removed using this method include, from alloy 718, Titanium Nitride and Primary deoxidation products containing aluminium and magnesium. Examination of FV458 shows deoxidation products containing aluminium and calcium.