Adhesion and Friction between dry coated particles
Xiaoliang Deng, Rajesh N. Davé
New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982, United States
Interparticle adhesion and friction play an important role in controlling the performance of particle materials. Dry coating method to achieve nanoparticle coating based surface modification has been experimentally shown as an efficient technique to manipulate adhesion and friction between coated particles in published literature [1-3]. During the coating process, the nanoparticles (guest particles) are deposited on the surfaces of large particles (host particles), thus forming surfaces with nanoscale roughness. A series of contact models have been developed for estimating the adhesion force interaction between such nanoscale roughness surfaces in contact, including the influence of the nanoparticle surface area coverage and inter-particle loading force [1, 4-6]. However, there is a lack of understanding for their influence on friction properties, which also depends on the adhesion force at contact. In this study, numerical investigations of the adhesion and friction properties of two contacting surfaces with nanoscale roughness have been performed. Depending on the specific properties of contacting particles, Johnson-Kendall-Roberts (JKR), Derjaguin-Muller-Toporov (DMT), and Maugis models are used to describe interaction between individual particles. Simulation results indicate that both adhesion and friction increase with increasing external compressive force. The adhesion and friction forces can be dominated by the host-host (HH), host-guest (HG), or guest-guest (GG) contacts, depending on the extent of surface area coverage (SAC) by nanoparticles. Those simulation results captured the main features observed in the physical experiments. Moreover, we then propose and formulate a probabilistic model capable of predicting the probabilities of HH, HG, and GG contacts as a function of the SAC. The theoretical predications match well with the numerical simulation results.
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