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The study and analysis of the kinetics of crystallization of copper melts showed that the modification of alloys with complex additives leads to a change in the structure of the melt, the conditions of crystallization and the separation of basic and excess phases. These changes consist in an increase in the range of order in the liquid metal, a decrease in the crystallization interval of the alloy due to a decrease in the liquidus temperature, an increase in the growth rate of the solid phase in the initial period of crystallization, a higher density of the modified melt and an increase in its growth rate. It has been established that for copper, a complex modifier in the amount of 0.6 wt. % with a ratio of activating additives and particles of inoculators is 2:1. [ABSTRACT FROM AUTHOR]

A method for pre-treatment of titanium carbonitride powders of modifying complexes is proposed, which consists in the fact that the particles are cleaned using ultrasound in a liquid medium from a melt of metal halide, and the cladding of these particles is carried out with metallizing additives dissolved in this melt. Such treatment of titanium carbonitride powders provides activation of particles and increases their fineness by five times, dimensional stability by seven times, and the number of particles of the nanoscale level increases up to eight times. [ABSTRACT FROM AUTHOR]

The results of a study of the properties of rubbers based on butadiene-nitrile rubbers (NBR) with different content of acrylonitrile (NAC) are presented. The mechanical characteristics of NBR-based rubbers with different NAC content under periodic load with a frequency of 1 Hz in the expected operating temperature range from minus 40°C to plus 60°C are determined. The change in mechanical properties was evaluated before and after thermal aging of rubbers. The conclusion is made about the operability of NBR-based rubbers with different NAC content before and after thermal aging. It is shown that rubber based on NBR-18 rubber at a temperature of minus 40 ° C reaches a plateau of high elasticity, which expands the range of its use in conditions of negative temperatures compared with rubber based on NBR– 40 rubber. [ABSTRACT FROM AUTHOR]

The composition of alloying elements for the basis of the metal composition is analyzed. The chemical composition of economically alloyed maraging steels for operation under conditions of impact-abrasive wear has been determined. The most promising alloying elements are manganese and chromium. The content of manganese up to 7% of the mass and chromium in the amount of 12% of the mass is optimal for surfacing products operating in conditions of impact-abrasive wear. [ABSTRACT FROM AUTHOR]

The tribotechnical characteristics of steel 10G7M3S2AFTYu obtained as a result of surfacing with flux-cored wire are studied. It has been established that the average value of the relative mass wear of such a metal is 0.0004085 g/m, and the average value of linear wear is 0.000882 mm/m. The friction coefficient during the running-in increased to 0.24, then fell to 0.20, and the average value for the test was 0.188. Before testing a polished sample, its greatest depth of profile depressions is 6.955 µm, and the arithmetic mean deviation of the profile is 0.571 µm. After testing, these characteristics are already 23.146 µm and 2.207 µm, respectively, which is 3.33 and 3.87 times higher than the surface before testing. The obtained tribotechnical characteristics show that steel 10G7M3S2AFTYu, obtained by surfacing with flux-cored wire, can be recommended for creating and restoring surfaces operating under conditions of metal-to-metal friction. [ABSTRACT FROM AUTHOR]

The paper presents an assessment of the possibility of increasing the dielectric constant of an epoxy press material by introducing a filler with a high dielectric constant, as well as the possibility of using a composite for the manufacture of an antenna element. Titanium dioxide (TiO2) functions as a filler. Since TiO2 has a high dielectric constant and its introduction makes it possible to obtain composite materials with higher radio technical characteristics, while titanium dioxide increases the strength, heat resistance, and weather resistance of the composite. The effect of TiO2 filling on the permittivity of a composite material based on an epoxy material is studied. The technology of manufacturing composite material samples by mixing components in a sampler pulverizer is described. Experimental samples of a composite material with a content of titanium dioxide – 7, 30, 35 % by weight-were studied. The modes of injection molding of plates and antenna elements made of new composite material are presented. The resulting antenna elements made of composite materials fully met the technical requirements of industry standards. The physicomechanical and dielectric properties of the composite, such as Shore hardness, permittivity, and shrinkage, are given. It is shown that the experimental values of the dielectric permittivity of the samples are consistent with the data calculated by the Lichtenecker formula. Experimental studies have shown that it is possible not only to increase the dielectric permittivity of the press material by introducing titanium dioxide but also to make structural parts with high radio technical characteristics from this material. It is established that the maximum filling of TiO2 increases the dielectric permittivity of the composite material by 60 %. [ABSTRACT FROM AUTHOR]

The article describes the influence of ultrasonic vibrations energy on the submolecular structure and tribotechnical properties of polymer composite materials based on polytetrafluoroethylene. Comparative analysis of the performed experiments showed that the introduction of ultrasonic vibration energy during pressing effects an increase in the wear resistance of polymer composite materials while maintaining low values of the coefficient of friction. In the friction process the submolecular structure changes because of a significant decrease in the size of crystallite blocks due to their fragmentation. [ABSTRACT FROM AUTHOR]

Three methods of improving the uniformity of the distribution of properties over the filtration area of powder filter materials (PFM) at different stages of their manufacturing technologies are considered. It is shown that granulation of metal powders with a pore-forming agent makes it possible to increase the uniformity of permeability distribution over the filtration area by a factor of 2.3-3.5 to produce PFM; dry radial-isostatic pressing provides a high uniformity of property distribution when producing long axisymmetric products: the coefficient of variation of the coefficient of local permeability does not exceed 0.17; radial compression of axisymmetric samples in the form of a disk makes it possible to increase the uniformity of the permeability distribution over the filtration area: the value of the coefficient of variation in this case is 15–22% less than in the original PFM. The choice of the method when used in practice is determined by the shape, size and properties of the manufactured products and initial powders. The considered methods can be used in petrochemical engineering for the manufacture of porous powder products for filtering purposes used to trap catalyst particles, filters for fine and coarse fuel and oil purification. [ABSTRACT FROM AUTHOR]