Carbide containing cordierite-mullite based filters for liquid metals

In this thesis, production and characterization of cordierite and mullite based filters and the effect of the carbide additives on the properties of these filters have been investigated. The natural raw materials such as Seydişehir alumina, kaolin, quartz, sintered magnesia and gibbsite have been used to produce of cordierite and mullite filters and also silicon carbide has been used as carbide additive. In the selection of suitable sponge, which determines skeleton structure of ceramic filters, properties of the different sponge samples, such as surface quality, structural parameters and thermal behavior, have been investigated. The mixture proportion of raw materials, and sintering parameters to produce cordierite and mullite phases have been determined. Preparation of slurry from these mixtures, and optimization studies of rheological properties of the slurries to suit the replication process, on the basis of solid content, dispersant amount and type, have been performed. Following the initial studies in the shaping stage, the range of silicon carbide addition has been determined on basis of its effect on the rheological properties of the slurry and sintering behavior of the materials. The characterization samples have been obtained by sintering in the phase transformation conditions of cordierite and mullite. Evaluating the results of physical and mechanical tests, and also microstructure and phase analysis, it is concluded that silicon carbide has a significant effect on the shrinkage, density, compressive strength, phase transformation and microstructures of cordierite and mullite foam filters. Effect of silicon carbide on the compressive strength of foam filters is discussed in detail in relation to relative density and strut strength.Keywords: Cordierite, mullite, silicon carbide, replication, ceramic filter