Rheological properties and gelcasting of concentrated aqueous silicon suspension

Zeta potential and rheological properties of silicon suspensions have been measured in this work. The results show that the isoelectric point of silicon particles is at the pH of 1.6. It is also found that silicon particles are suitable for suspending in basic solution, provided that a proper pH value is chosen. Silicon suspension with 46 vol.% particles displays a minimum viscosity at the pH of 9.6. The influence of particle concentration on the rheological properties of aqueous silicon suspensions is investigated under steady and oscillatory shear conditions. Furthermore, gelcasting of high concentrated aqueous silicon suspension is also discussed in this paper. By vacuum pumping, controlling pH values of suspensions, high volume fraction green bodies with uniform structure and certain strength were produced.