Study of Slurry Properties and the Possible Theoretical Prediction for Controlling the Thickness of Nanoparticle Alumina Coat Layers

Abstract

The properties of slurries were examined for controlling the thickness of the coat-layers which were vertically drawn from the pool of catalytic nanoparticle alumina suspension. The present slurries showed non-Newton flow behavior and the thickness increased with the increase of the solid concentration. The pseudoplastic flow at low shear rates changed to the Bingham flow in which the plasticity viscosity was obtained in high shear rate region. The relation among various parameters was checked and examined toward the use of the theoretical relation in the Newton fluid to obtain a layer thickness. We found the possibility of the method that could estimate the thickness of coat layers if the plasticity viscosity of the Bingham flow region was applied. The results showed the partial consistence between experimental and calculated thickness of thin layers. The factors of inconsistence were discussed in details using the schematic model which contained the transition phenomenon between the pseudoplastic flow and the Bingham flow. The film-drawing procedure under the high shear rate condition was suggested for better controlled thickness.