FABRICATION OF RETICULATED POROUS MULLITE REFRACTORIES (RPMR) AS A MOLTEN METAL FOAM FILTER

摘要

In this work commercial polyurethane sponge with open porosity of approximately 20 ppi where chosen as a template to produce the RPMR via Polymeric Sponge Replica Method from a shearthinning multicomponent aqueous slurry which was composed of Alumina, SiC, Colloidal Silica and some different additives. By rolling the polymeric sponge which had been immersed into the slurry, a uniform open-cell structure was produced. A cellular structure was then dried, the polymeric sponge was pyrolyized, and the ceramic foam was allowed to gain its ultimate strength, composition and structure. The thermal transformation sequence of the mixtures, resultant macrostructure and microstructures, relative density, grain morphology, phase compositions, and mechanical strength of sintered sample were investigated. The mechanical properties of struts were investigated by theoretical model. The statistical evaluation was carried out on mechanical strength data of sintered bodies using weibull statistic. It has been shown that high density Mullite can be manufactured via a Transient Viscous Sintering (TVS) of composite powders and also via reaction- bonding route from the powder mixtures of alumina (Al_2O_3) and silicon carbide (SiC) in the present of silica sol as a source of SiO_2. During heat-treatment in air, SiC oxidized to SiO_2, this reacted with Al_2O_3 to form Mullite. This study shows that the RPMR due to its potential properties can use in many applications such as molten metal filter, catalyst supports, and hot gas fitters.