2015 Volume 32 Issue 2 Pages 135-147
Recently, there are a few studies of the engineering properties of the aqueous suspension of nano particles (whose diameter is less than 1 μm). The purpose of this study was to investigate the freezing behavior and freeze concentration of the aqueous suspension of nano or micro silica particles. It was confirmed that the average supercooling degree of the aqueous suspension of nano and micro particles decreased with increasing mean particle diameter. The ice crystal grain of aqueous suspension of micro particles by a polarization microscope observation was smaller than that of nano particles at low cooling rate. From the progressive freeze-concentration technology, it was found that the freeze concentration ratio of aqueous suspension of micro and nano particles increased as the freezing percentage increases in the agitating condition, but there was no freeze concentration of aqueous suspension of micro or nano particles in non-agitating condition because of the particle precipitation or the high cooling rate. It was observed that there was no difference of the freeze concentration ratio in case of an increase of particle diameter. In addition, it was noticed that the freeze concentration ratio decreased in decreasing the agitating rotation and increasing the initial concentration of aqueous suspension.
