Атомістичне моделювання трибологічних явищ у нанорозмірних системах, що містять вуглецеві поверхні

Abstract

The thesis is devoted to theoretical investigation of friction and wear at the atomic level in nano-dimensional systems containing surfaces of diferent allotropic forms of carbon. With this aim, corresponding atomistic models have been developed and classical molecular dynamics simulations have been carried out. The existence of solidlike state was revealed for loads higher than 430 MPa and temperature of 298 K in ultrathin water lm con ned between rigid diamond surfaces. This state is characterized by low value of the difusi- on constant and the presence of ordered con gurations of molecules for the atomically- at surfaces. It was established that the friction force acting on the upper wall obeys the rst Amontons' law under low loads, and saturation is observed at high loads. Exfoliation of graphite as a result of the interaction with adhesive tip at the temperature of 298 K occurs when the interaction energy is greater than or equal to 0.5 eV per atom and the lattice constant a of the tip is equal to 0.3165 nm. It was shown that the nanoasperity flossesf the graphene layer when the energy is 0.25 eV and 0.1 eV for a = 0.3165 and a = 0.1583 nm, respectively. The simulations revealed that the dependence of the friction force acting on Ni and Ag nanoparticles from graphene on the position of their center of mass has sawtooth and random shapes, respectively. The dependence of time-averaged friction force on the contact area is linear, and the slope of linear approximation is 1.21 pN/nm2. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20796