Nanoindentation of particulate coatings

A knowledge of the formation and rupture mechanisms for agglomerates is ess ential when seeking to model equipment designed to produce and process such materials. In the work described here, nanoindentation of "two-dimensional " agglomerate films, basically particulate coatings, was carried out to est ablish a means of identifying the generic breakage mechanisms for agglomera tes. Selected applied load and penetration depth data in the range (0.02 mN and 700 nm, respectively) are provided as a function of the loading: time during continuous loading for a model system composed rather of monodispers ed colloidal silica particles (20-24 nm diameter) bound with a poly(methyl methacrylate) at 5 vol%. It is argued that these data enable the sequence o f binder bridge failures to be observed, thus giving an indication of the b reakage mechanism of the agglomerate and also the strength of the individua l junctions. These data are also incorporated into a mechanical model that describes the rupture and deformation behavior of these planar agglomerate systems.