Shear-rate dependence modeling of gelcast slurries: Effects of dispersant content and solid loading

Gelcasting, as a ceramic forming technique, is getting worldwide attention, in that it can be used to make high-quality, complex-shaped ceramic parts with a wide range of powders. However, a model, which can appropriately describe the shear rate dependence behavior of the slurry in casting process simulation, is limited. Therefore, this study mainly sought to investigate the best model representing the behavior of as-prepared gelcast slurry. A premix solution was prepared with monomer/cross linker of AM/MBAM with ratio of 25:1. In this procedure, ammonium polyacrylate sodium (NHPANa) was used as the dispersant and the solid load included Al2O3/20 vol% ZrO2 powder mixture. Series of slurries with different dispersant contents and solid loadings were prepared to investigate Shear-rate dependence behavior, using “Cross”, “modified-Carreau” and “Carreau-Yasuda” models. Results further revealed that Carreau–Yasuda model with variant parameter ‘a’ proved the best fit on rheological behavior of gelcast slurries. Moreover, the results showed that the parameter ‘a’ for gel-cast slurries is around 3, which is much more than “Cross” and “modified-Carreau” models.