An AFM study of the interaction between an ?-alumina particle and a flat sapphire surface in high ionic strength electrolyte solutions

Abstract

A colloid probe method has been used to characterize the normal and lateral forces between a hydrophilic ?-alumina particle and a c-sapphire surface (0001) at pH 11 in various KCl electrolyte concentrations. The normal forces are repulsive at all ionic strengths measured. The electrical double layer thickness is compressed at high electrolyte concentrations, which is evident from the decrease in the interaction distances observed in the force-distance curves. At high electrolyte concentrations, the friction forces decrease between the alumina surfaces due to the lubricating effect of the hydrated cations. © 2009 Elsevier B.V., All rights reserved.