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Electrostatic Stabilization of Alumina Nanopowder Suspensions

2014-03-01
Çınar, Simge
AKINC, MÜFİT
Electrostatic stabilization has an impact on a broad range of applications. Previous research has shown that concentrated alumina nanopowder suspensions can be stabilized at specific ranges of ionic strength and pH. This study investigated the stability of alumina nanopowder suspensions in terms of viscosity measurements as a function of different electrolyte concentration and suspension pH. Using alumina nanopowders with an average particle size of about 50 nm, stable suspensions were obtained with 0.020 ≤ [NaCl] ≤ 0.040 M or in the range 4 ≤ pH ≤ 7. The observed suspension stability was investigated by zeta potential measurements and explained with the DLVO theory. The effective volume fraction of solids brought about by bound water (or swelling), surface charge, and the compression of the electrical double layer were three plausible control mechanisms for the rheological behavior and electrostatic stabilization of alumina nanopowder suspensions with high solids content.