Nanoindentation of particulate coatings

摘要

A knowledge of the formation and rupture mechanisms for agglomerates is essential 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 establish a means of identifying the generic breakage mechanisms for agglomerates. 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 monodispersed 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 of binder bridge failures to be observed, thus giving an indication of the breakage mechanism of the agglomerate and also the strength of the individual junctions. These data are also incorporated into a mechanical model that describes the rupture and deformation behavior of these planar agglomerate systems.