Lateral force microscopy study of the friction between silica surfaces

The friction between a single silica glass sphere and a flat silica glass s urface has been investigated using lateral force microscopy. Two types of s ilica surface were investigated, one fully hydroxylated and the other parti ally dehydroxlated. These samples have markedly different wetting propertie s and are known as hydrophilic and hydrophobic silica, respectively. The la teral friction force as a function of applied normal load has been collecte d for five different-sized spheres for both surface types. Analysis of the friction versus load data indicates that the hydrophilic surfaces have a mo lecularly smooth contact. For the hydrophobic surfaces, it is not clear whe ther the friction-load response is caused by a smooth or an asperity-domina ted contact zone. (C) 2000 Academic Press.