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The effect of acidic, alkaline and neutral media on wear kinetics and mechanism for fluoroplastics and polyolefins has been studied. Equations for fluoroplastic and polyolefin wear intensity are obtained based on the thermochemical and mechanical model of their destruction. The values of the activation energies for the surface destruction onset over the entire wear cycle of the polymer surface spherulite are determined.

It has been established that carbon plastics are increasingly used in various industries as structural materials. By the set of their properties, carbon plastics outperform steel, cast iron, alloys of non-ferrous metals. However, the application of these materials for parts of machine friction units is still limited due to the difficult operating conditions of modern tribosystems. This work aims to conduct a comprehensive experimental study of the tribological properties of materials in the tribosystem "carbon plastic-metal" taking into consideration their structure, as well as the mechanical-thermal characteristics. Comparative tests of the dependence of the friction coefficient on load for metal and polymeric anti-friction materials have shown a decrease in the friction coefficient for plastics by 3...4 times (textolite, carbotextolite, and carbon-fiber plastics). The influence of the filler orientation relative to the slip plane on the anti-friction properties of carbon-fiber plastics was investigated; it was found that the direction of fiber reinforcement in parallel to the friction area ensures less carbon-fiber plastic wear. A linear dependence of the wear intensity of carbon-fiber plastics, reinforced with graphite fibers, on the heat capacity and energy intensity of the mated steel surface has been established. Based on the microstructural analysis, a layered mechanism of the surface destruction of carbon-fiber plastics was established caused by the rupture of bonds between the fiber parts, taking into consideration the direction of the fibers' location to the friction surface. The results reported here could provide practical recommendations in order to select the composition and structure of materials for the tribosystem "carbon-fiber plastic-metal" to be used in machine friction units based on the criterion of improved wear resistance

The paper shows the prospects of nitriding in a cyclically switched discharge, the classification of nitriding processes in a glow discharge according to the criteria of the characteristics of the power source is given. A comparison of the advantages and disadvantages of nitriding processes with constant and cyclically switched discharge is given.From a theoretical point of view, the process of nitriding in a cyclically switched glow discharge  is considered based on the concept of an energy model. In accordance with this model, tasks for further theoretical and experimental research are formulated. It is shown that the process of surface modification in a cyclically switched discharge opens up new possibilities associated with variants of the CSD itself, which is characterized by: frequency, period and pulse shape. The implementation of the process of adjusting the switching frequency, pitch - the ratio of the cycle period to the duration of the signal, and the shape of the signal itself opens up wide opportunities to significantly influence the results of surface treatment. The influence of the shape of the discharge power signal on the kinetics of the nitriding process and its results opens up wide opportunities for studying the process itself. The presence of surges at the beginning and at the end of the cycles can, in principle, significantly affect both the nature of the nitriding process itself and the structure and phase composition of the modified surface layer, since short-term and sufficiently powerful voltage surges should lead to intensive surface sputtering. The destruction of the monolayer of nitrides, which has just formed on the surface, will contribute to the increase of the depth of the nitrided layer due to the diffusion of nitrogen particles, as well as to a certain extent leveling off the blocking effect of the surface nitride layers.

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In the paper, based on the analysis of literary sources and own researches of authors, the results of cavitation and erosion wear resistance of structural steels are systematized depending on their thermal processing (structure) and type of environment.The structural structure of steels is based on the analysis of wear resistance during cavitation and erosion fracture of surfaces, and the mechanisms of cavitation fracture of dodectoid, zavectotoid and perlite steels are considered.Destruction of dodectoid steels begins with ferrite, and then extends to perlite grains. The wear resistance of the pearlite grains of the plate-shaped form is higher than that of perlite of the granular form. Cavitation wear resistance of zeutectoid steels is determined mainly by the properties of perlite. The mechanical properties of which depend on the dispersion and shape of the particles of cementite.In perlite steels, reducing the size of its grain increases their erosion resistance, especially in the presence of cementite in the structure of the grid, and not ferrite grids.Using different types of thermal and thermocyclic heat treatment, it is possible to form appropriate structures and, accordingly, increase the cavitation and erosion wear resistance.

One of the most important factors for the development of modern agricultural entrepreneurship is the stable and productive conduct of agricultural production. The main purpose of the article is to study the rate of moisture release after harvesting winter crops and to find the optimal sowing time after harvest. All studies were conducted in real production conditions in accordance with the developed research methodology. Modern devices of different types were used to obtain the most reliable values. An important factor for obtaining high yields is the full disclosure of the potential of available moisture and air in the upper fertile layer of the soil. Gradual movement of climatic zones to the north of Ukraine requires the study of the rate of moisture release from the soil and the determination of the most optimal terms for sowing. In a fairly dry period, the beginning of sowing of winter cereals is necessary immediately after harvest at soil moisture – 17-22 %. All necessary agricultural measures to prepare the soil in summer for winter crops (background and main tillage) should be carried out taking into account the basic principles of the theory of "differentiated humidity", according to which the main amount of soil moisture in the range of GWP (marginal field moisture content) is lost due to the upward movement of water through macro- and micro-wells. One of the methods to reduce moisture loss is to create a loose layer on the soil surface, which prevents capillary leakage of moisture and acts as mulch. The loose layer itself significantly slows down the heating of the surface and interrupts the flow of moisture to the evaporation horizon, so it is recommended immediately after harvest to remove straw from the field for loosening the top layer of soil. Significantly reduce the drying of the soil gives some compaction of the soil in its upper layer, which reduces the loss of steam, by moving balers and bales of straw on the surface of the field.