Relationship between rheological properties of slurries and pore size distribution of cast and compressed compacts of mullite

Colloidal stability–slip casting behavior relationship in slurry of mullite synthesized by the USP method

“…Electrokinetic studies revealed that the IEP for mullite was at pH 8.9. This is in agreement with the result of a study by Hashi and Senna [21]. Burgos-Montes and Moreno, on the other hand, have reported a pH value of 5.9 for the IEP of mullite produced by the combustion synthesis method in the presence of background electrolyte, 10 À2 M of NH 4 NO 3 [23].…”

“…Consequently, as seen clearly in Fig. 5, the IEP of the mullite powders used in this study corresponds to a pH value of 8.9 which is very close to the IEP (pH 8.7) of crystalline mullite studied by Hashi and Senna [21]. However, there is a significant difference between the IEP values of mullite obtained from spray pyrolysis method used in the present study and the combustion synthesis method (pH 5.9) utilized by Burgos-Montes and Moreno [23].…”

“…The present research aims to contribute to the relevant literature by providing a detailed discussion on the effect of pH on the slip casting behavior of mullite slurry without dispersant, and consequently on the microstructure of green compacts and sintered products manufactured from mullite produced by the USP technique. Another objective of this investigation is to resolve the discrepancy between the IEP values of mullite reported by different researchers [21,23].…”

“…Nevertheless, in order to fully determine the stability and flow characteristics, and explain the stabilization mechanisms of slurries containing different types of minerals, the stabilizing conditions for each constituent in the mixture must be identified. Published researches on the microstructural and physical properties of products manufactured from mullite alone by the slip casting are scanty [21][22][23]. Tkalcec et al investigated the effect of sintering temperature on the mechanical properties and microstructure of products obtained by slip casting of refined mullite powders prepared by the sol-gel technique [22].…”

“…They obtained strong sintered products from mullite slurry with polyacrylic acid dispersant. The work of Hashi and Senna appears to be the only attempt to study the influence of pH on the stability of mullite slurry and in turn on the green and sintered products [21]. They examined the relationship between the pH and the rheology of mullite slurry and pore size distribution of the green compacts.…”