Mechanical surface preparation is a common technique for removing contaminants from surface metal layers. Unlike chemical preparation, it does not require special safety measures, including those for disposal of by-products or toxic materials, thus making it more accessible for different industries. We investigated tribological testing as the experimental method to determine the quality of the coating and the influence of the initial mechanical surface treatment. Samples were made of aluminium alloy EN AW 5083 H111 that was shot blasted with white cast aluminium with resulting surface roughness of Rz=38.908 μm. Samples were further coated with Lankwitzer EvoCor 164 2-component epoxy primer. Tribological test realised on nanotribometer is described and output parameters have been analysed: friction coefficient and penetration depth. Ball-on-flat, dry contact tribological setup was used, with 100 mN normal load, under linear reciprocating motion. Dynamic friction coefficient and penetration depth curves during one tribological test were analysed indicating the moment when the coating exhibited first failure. The test has shown that tribological tests with low loads can be used for quality testing of thin coatings, including the influence of the mechanical surface preparation on the coating adhesion.

Deterministic and stochastic models of Brownian motion in ferrofluids are of interest to researchers, especially those related to drug delivery systems. The Brownian motion of nanoparticles in a ferrofluid environment was theoretically analyzed in this research. The state of the art in clinical drug delivery systems using ferromagnetic particles is briefly presented. The motion of the nanoparticles in an external field and as a random variable is elaborated by presenting a theoretical model. We analyzed the theoretical model and performed computer simulation by using Maple software. We used simple low-dimensional deterministic systems that can exhibit diffusive behavior. The ferrofluid in the gravitational field without the presence of an external magnetic field in the xy plane was observed. Control parameter p was mapped as related to the fluid viscosity. Computer simulation showed that nanoparticles can exhibit deterministic patterns in a chaotic model for certain values of the control parameter p. Linear motion of the particles was observed for certain values of the parameter p, and for other values of p, the particles move randomly without any rule. Based on our numerical simulation, it can be concluded that the motion of nanoparticles could be controlled by inherent material properties and properties of the surrounding media, meaning that the delivery of drugs could possibly be executed by a ferrofluid without an exogenous power propulsion strategy. However, further studies are still needed.

A focus of frontline interdisciplinary research today is the development of the conceptual framework and the experimental background of the science of nanostructured materials and the perspectives of its technological applications. G. Guisbiers and L. Buchaillot found out the general equation (GBE) which was based only on the surface area to volume ratio of nanostructures and statistics (Fermi-Dirac or Bose-Einstein) followed by the particles involved in the considered phenomena (melting, ferromagnetism, vibration and superconductivity). In this paper, we consider another phenomenon, the regularity-chaos transition, and find its connection with GBE. We have performed the computational experiments with one hydrogen molecule and one graphene sheet. H 2 -C interactions are described by Lennard-Jones potential. The main goal of our experiments is find out the critical temperatures of regularity-chaos transition. The results of computation derived using Runge-Kutta-Fehlberg method show approximate agreement with GBE.

A model of the AFM (atomic force microscope) with certain tip-nanostructure interaction, cantilever elasticity and damping of its oscillations is proposed. Stable and unstable motion of the AFM tip interacting with the graphene sheet is investigated by the Lyapunov exponent computation. In our approximation, a hundred Si atoms (top of the AFM tip) interact with C atoms of the nanostructure. Тhis interaction is described by Lennard-Jones potential, and the distance between the top and the center of the cantilever mass is a constant. Complex influence of the initial tip-nanostructure distance and nanostructure size on stability has been examined. We discuss a possible new mode of the AFM operation based on the Lyapunov exponent computation. Maxima and minima of the Lyapunov exponent show where certain parts of the elementary cells are placed.

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