Sintering and characterization of starch consolidated porous mullite bodies

M.H. TALOU; M.A. CAMERUCCI

Portland

Conferencia; 12th International Conference on Ceramic Processing Science; 2013

Among the direct consolidation methods involving gelation, the starch consolidation casting (SCC) is a non-contaminating low-cost technique in which the starch acts as a consolidator/binder of the ceramic suspension and as a pore former at high temperature.  In this work, the processing and microstructures of porous mullite bodies prepared by modifying SCC were studied. The alternative processing route called Mixing Route (MR) was proposed to prevent particles segregation observed in bodies prepared by conventional route, and thus, to develop porous bodies with homogeneous microstructures. Stable aqueous mullite/cassava starch suspensions (0.25 starch volume fraction of 40 vol.% total solids) were prepared by mixing and homogenization. The total starch content was a mixture of ungelatinized/gelatinized native starch in a 9:1 ratio. Mullite porous bodies were obtained by heating (80°C, 2h) the aqueous mullite/starch suspensions into metallic molds, burning out treatment (650°C, 2h) and sintering at 1400, 1500 and 1650°C, 2h. The phase evolution and microstructures were studied by XRD analysis, Hg-porosimetry and SEM. The porosity values (total, open and close) were obtained by water immersion method. The close porosity increased and the total porosity decreased by increasing sintering temperature. At 1650°C, homogeneous porous microstructures (42%) of mullite were obtained. The cavity (10-20mm) and throat sizes (3.3-5.4mm) did not change with the sintering temperature.