Investigation of effective Parameters on Fabrication of Silicon Carbide Ceramic Foam Filters to Application in Cast Iron Foundries

One of the most effective methods to remove inclusions and impurities in metals foundry are the use of porous ceramic filters. In the gating system these filters can remove slags and other types of inclusions and contaminants from melt. In order to make silicon carbide-based ceramic foam filters SiC-(CFF) in the research, we used Polyurethane sponge in ceramic slurry by replica method. Ceramic slurry contain silicon carbide, alumina, ball clay and zircon fine particles in the micron and sub-micron size. To increase the adhesive properties and create thixotropic behavior, other additives such as colloidal silica and carboxymethyl cellulose (CMC) were added to slurry. After making the filters, mechanical and microstructure properties of them were studied. Mullite phase along silicon carbide phase formation in microstructure of filters, is one of the reasons that causes increasing in compressive strength and refractoriness. Existance of, these phases was proved by XRD analysis. Finally to compare the performance of these filters with the imported one, molten ductile iron passed through them and the density of the castings was studied. Results showed that disperse and completely homogenized that these filters performances are as good as the imported ones. Microstructure studies by SEM showed silicon carbide and mullite ceramic phases formed in microstructures of the filters.