Study on Rheological Behavior of Nanosized CeO_2 Suspension

The rheological behavior of polishing slurry plays an important role in the chemical mechanical polishing.In this research,the rheology property of nano-ceria slurry is investigated.The effects of pH,particle concentration,temperature and electrolyte concentration are discussed.It is shown that a lower zeta potential gives rise to a higher apparent viscosity and results in the observed shear thinning property.In the suspension if the particle concentration is below 17.4wt%,the nano-ceria slurry exhibits Newtonian behavior and further addition of CeO2,higher apparent viscosity and shear-thinning behavior is observed.The influence of temperature on rheology property of CeO2 slurry appears more complex.When the temperature is lower than 35 ℃,the apparent viscosity of the CeO2 slurry decreases with temperature increases.But when the temperature is higher than 35 ℃,increasing temperature results in the apparent viscosity increasing.If the electrolyte is added into the slurry,a shift of apparent viscosity to a higher value is observed due to the decreased zeta potential.