International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Calculation of thermal diffusion and filtration fluxes at the interface by “traditional” methods requires preliminary determination of the potential values (concentration, moisture content, temperature, pressure) in the four-dimensional space of events. Such methods for solving boundary value problems, which provide “extra” information for technical calculations, are usually very laborous and require the use of numerical methods that are not always convenient in engineering practice. The proposed fieldless calculation method allows one to determine on the boundary of the region the gradients from the transfer potentials and, consequently, energy and material flows in the form of a known functional of the potentials at the interface at their short-term contact directly on the matrix of transfer coefficients of the formalized boundary value problem. This method uses the fractional index differentiation operation (fractional differentiation) and is convenient for solving limiting boundary value problems, i.e. when the characteristic size of the contacting phases in the boundary conditions of boundary value problems tends to infinity or the time of their interaction tends to zero.

Using the methods of systemic, mathematical and numerical analysis, as well as general physicochemical and thermodynamic laws, a complex of theoretical and experimental studies of transfer processes during short-term contact of phases has been carried out. These studies made it possible to fully reveal the regularities of external and internal heat and mass transfer, to find scientifically grounded ways to intensify the processes of vacuum, conductive and combined drying methods. Within the framework of linear nonequilibrium thermodynamics, a mathematical model of filtration-diffusion energy and mass transfer has been developed with a correct estimate of the orders of the terms in the system of differential equations of energy and mass transfer, taking into account the composition of the vapor-air mixture in the capillary-porous body. The limits of applicability of the hypothesis of short-term contact of phases according to the Fourier criterion for the transfer inside and outside the surfaces of the canonical shape (plate, cylinder, sphere) and wedge are estimated from the standpoint of the accuracy of calculating interphase flows. It is shown that in a number of cases the contact is not short-lived due to the curvature and the presence of angles on the contact surface, and not due to the finiteness of the dimensions of the contacting phases.

The paper presents the results of a research focused on the application of laser surfacing of functional surfaces using an additve material in the form of a wire. Cladding is made in a single layer using a robot. The quality of the cladding layer was evaluated by ultrasonic inspection. Possible occurrence of internal defects was assessed. Macrostructures and microstructures were analyzed on metallographic sections using light microscopy. Influence of the used additive material and the cladding parameters on the microhardness behaviour in the individual parts of the test specimens was also evaluated.

The contribution is focused on the analysis of the roughness of metal surfaces after applying a conversion layer using phosphating. The types of basic materials is used in the experiment hot-dip galvanized microalloyed steel HX340LAD+Z. During the application of the conversion layer, changes in surface roughness were studied with respect to the phosphating time, which was 3, 5 and 10 minutes. The paper deals with the evaluation of the relationship between the individual roughnesses parameters of pre-treated surfaces using correlation analysis. Based on the measured roughness values on the surfaces, the standard of statistical significance of the correlation between the observed parameters was determined from them. The achieved results provide information for other technological operations such as the creation of adhesive joints, where the correct anchoring of the adhesive is important for load bearing capacity of joints.

Currently, one of the most important and monitored surface properties is the ability to achieve the highest possible level of adhesion after applying a layer of paint or glue. To guarantee this property, it is extremely important to choose the right surface pretreatment. The paper is focused on chemical surface pretreatment and subsequent evaluation of morphological surface changes after application of various selected types of chemical pretreatment based on roughness parameters.

The main goal of this contribution is study the microgeometry of blasted surfaces. The aim is to design suitable microgeometric characteristics for the description of pretreated surfaces, experimentally verify the influence of blasting agents of various shapes and sizes on the microgeometry of metal surfaces. The following types of evaluation are used to meet this goal: 2D roughness determinat ion and profilograms, 3D surface visualization and surface volume determination. The results of the experimental part will contribute to the optimization of technological parameters of the tearing process.

The paper presents the possibilities of renovation of worn functional surfaces of roll for continuous steel casting. The cylinder was made of steel 24CrMoV55 – DIN 17240. The lifetime of the continuous casting line roll is limited by the quality of their functional surface. The worn roll is decommissioned and the extent of its damage has been assessed. Cracks are a limiting factor in deciding on its renovation. Renovation of functional surfaces of roller from a diameter of ø 200 mm is realized by technology submerged arc welding (SAW). The article presents the results of research into the quality of newly formed cladding layers. Their quality was evaluated using non-destructive and destructive tests. Based on the performed experiments, it can be stated that the used surface renovation procedure is suitable for the renovation of functional surfaces of continuous steel casting rolls.

Surface quality and its evaluation is currently a very important part of surface preparation for all types of technologies involved in surface formation. Knowledge of the new surface formation mechanism is of great importance from the point of view of production, because it allows to understand the nature and properties of the newly created surface and thus gives the opportunity to both improve the processes used and create a smooth process. surfaces. Therefore, any changes that occur in the surface layer of the component can be considered as changes in the surface quality. The paper deals with the expansion of current knowledge in the evaluation of metal surfaces microgeometry in terms of current trends.

The quality of the resulting surface treatment is influenced especially by the pre-treatment of the substrate, the design of the surface treatment such as the choice of the coating system, the method and the quality of application. From a variety of chemical surface pre-treatment methods, Bonderite chemical pre-treatment is at the forefront. This chemical pre-treatment is used at ambient temperature, phosphate-free. It forms a nano-ceramic protective layer on steel, zinc and aluminum surfaces. The use of Bonderite gives the coating a high quality, which shows good adhesion and excellent corrosion protection. Contribution is devoted to the evaluation of these properties

The principles and peculiarities of the molecular layering (ML) method, known often in foreign works under the name of Atomic Layer Deposition, are considered. ML method was created in the middle of the last century by Soviet-Russian scientists V. B. Aleskovskii and his student S. I. Koltsov. Among the first who after Russian scientists began to carry out research on the method of ML were scientific groups from Finland (T. Suntola, S. Hauk, M. Leskela, M. Rital, etc.), the GDR (V. Hanke, G. Olman, B. Horvath and others), Bulgaria (G. Bliznakov, K. Petrov, D. Mekhanjiev, D. Damianov and others). The structural-dimensional effects manifested in products obtained using the ML method are analyzed. The results of practical application of nanotechnology on the principles of the ML method in various high-tech industries are presented: sensor sensors, membrane catalytic processes, catalysts, sorbents, composite materials, alternative energy sources, electret materials etc.

On the basis of modern concepts of condensed matter physics and quantum physics considered the criteria for inclusion ofdispersed particles of different composition, structure, and technological background to nanomodifiers of polymeric, oligomeric and combined matrices. There were proposed an analytical expression for the evaluation of limiting size of the dispersed particles L₀, which characterizes the manifestation of a particular energy state – nanostate.There was implemented the analysis of experimental and literature data confirming the adequacy of the calculated value of the size of particles in nanostate obtained using relation L₀=230•θ_D^-1/2, where θ_D – Debye temperature. It is shown that the provision of effective modification of macromolecular matrices necessary and sufficient condition is the presence of dispersed particles of different composition and structure of nanoscale structural fragments of the surface layer, which ensure the implementation of synergies through a combination of energy and mechanical factors in the formation of boundary layers of the optimal structure.