(7c) Controlling the Interparticle Forces of Nanoparticles Using Atomic Layer Deposition

The adhesive 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. An Atomic Force Microscope (AFM) with a chemically modified tip 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. The improved dispersion, fluidization and flowability of coated particles are also tested.