(160i) Controlling the Interparticle Forces of Nanoparticles Using Atomic Layer Deposition

The attractive London-van der Waals forces between primary ceramic nanoparticles are modified by coating the nanoparticles with ultrathin alumina films using Atomic Layer Deposition. The deposited alumina films are extremely conformal and uniform. The macroscopic behavior of nanoparticles is compared in dry systems as well as in solution. The improved dispersion, fluidization and flowability of coated particles are also tested using measurements of angle of repose, minimum fluidization velocity, bed expansion, Hausner ratio, zeta potential, viscosity and sedimentation velocity. An Atomic Force Microscope (AFM) is utilized to measure adhesive interactions between reference substrates and nanoparticles before and after coating. Various ceramic nanoparticles (Titania, Silica and Zirconia) were nanocoated in a fluidized-bed reactor at low pressure and under mechanical vibration. The average growth rate of film is only 1.1 Angstroms per coating cycle.