Surface Engineering and Applied Electrochemistry最新文献

A model of heat transfer in the cathode spot region of a vacuum arc of pure metals is constructed and the process of formation of microdrops generated by a cathode spot is described on its basis. Analytical expressions determining the diameter of microdrops and its functional dependences on the parameters of the vacuum arc discharge are obtained.

The results of a study of chip formation during turning of hardened steels 40Kh, SHKh15, and R6M5 with a hardness of 50–65 HRC using a tool based on cubic boron nitride (CBN) are given. The effect of cutting modes and microgeometry of the working surfaces of the blades on the shrinkage and shape of the chip is shown. The change in the morphology of ground and diamond-lapped working surfaces of the blades during the cutting process is considered and the effect of its transformation on the dynamics of the turning process and the quality of the machined surfaces is shown. It is demonstrated that the morphology of the blade surface affects the processes of contact interaction between the tool and the workpiece materials, the shape of the chip and, after finishing, provides tribological contact conditions that reduce thermal stress and dynamic disturbance during a long cutting process.

A method for the synthesis of G-phases (~90 vol % content) at low temperatures and short duration of heat treatment is proposed. Ti₆Co₁₆Si₇, Ti₆Ni₁₆Si₇, Ti₆Al₁₆Fe₇ and Ti₆Al₁₆Co₇ G-phases were synthesized by mechanical alloying of pure constituent elements and subsequent heat treatment at 600 or 900°C for 1 h. The structural-phase state of mechanically alloyed and annealed powders has been studied, and the temperatures of the formation of G-phases have been determined.

Aspects of the theory of metal forming are developed in sections of the theory of cross rolling, its subsection of the theory of cross wedge rolling, the phenomenological deformation theory of metal fracture, and the energy theory of metal fracture during plastic flow.

The article considers the features of the local plasma electrolytic treatment by the jet feed of an electrolyte onto the side surface of a rotating cylinder made of low-carbon steel. The influence of hydrodynamic parameters of the treatment and voltage on the electro- and thermos-physical characteristics of the process was studied. The optimum values of the electrolyte flow rate, the nozzle diameter, and the distance between the sprayer and the treated surface were established that meet the developed conditions for the efficiency of the local plasma electrolytic treatment. Volt-ampere and volt-temperature characteristics of the process that have common patterns with the treatment by the immersion method when the operating voltage range is shifted towards higher values were obtained. A technique for determining the heat flux into a metal sample during the local treatment with an electrolyte jet was developed based on temperature measurements performed outside the heated area, using which the features of the heat exchange in the electrolyte–vapor–gas layer–rotating cylinder-electrode system were studied.

This paper presents the results of the study of the influence of the microwave electromagnetic field on the properties of the epoxy basalt-filled oligomer and the composite obtained on its basis; the relevance of the study is substantiated. The existing technological schemes of microwave modification of thermoplastics and the novelty of the proposed solution are considered. The influence of the electric field strength of the electromagnetic wave on the epoxy basalt-filled oligomer has been established, at which the maximum modifying effect is achieved, which is of great scientific and practical importance for the development of the technology of microwave modification of the oligomer. The results of resistance to various aggressive media have been obtained, which show that the studied physical and mechanical characteristics of the epoxy basalt-filled material after exposure to aggressive media decrease by less than 14%, which corresponds to their good resistance to aggressive media. Thus, the effectiveness and expediency of using a microwave electromagnetic field for the modification of a basalt-filled epoxy oligomer and a composite obtained on its basis has been proven.

The mechanical, physicochemical, chemical, and thermal methods of separating the cathodic material from aluminum foil as one of the stages of lithium-ion battery recycling are considered. It was shown that the most effective methods according to the criteria for the possibility of scaling the technology, as well as material, energy, and labor costs, are chemical and thermal methods, providing the degree of cathodic material extraction up to 100%.

The paper presents a methodology for selecting the ion nitriding mode for parts depending on design documentation, the type of parts, and steel grade. The methodology is developed for equipment having working chambers with water-cooled walls. The criteria for selecting the temperature, pressure, and composition of working gas are set forth.

The source of energy for the generation of electromagnetic radiation by an oscillating charged drop of viscous liquid is discussed. It is shown that the source of electromagnetic radiation is the thermal energy released in the drop during its oscillations due to viscous dissipation of the mechanical energy of oscillations.

The work determines the possibility of induction-thermal vacuum sputtering of a molybdenum target and the formation of molybdenum-containing layers on alumina substrates. In the process of numerical simulation of the inductor–chamber–target–sample system, the influence of the inductor current on the target heating temperature and heat distribution over the cross section of ceramic samples was studied. Modeling consisted in solving problems of electrodynamics and nonstationary heat transfer. Taking into account the results obtained in numerical simulation, technological equipment was manufactured, and the process of forming molybdenum-containing layers on Al₂O₃ was carried out at a residual pressure of the gaseous medium of 55 ± 25 Pa, an inductor current of 6.56 kA, a deposition distance of 5–17 mm, and a process duration of 600 s. It has been established that the oxygen content in the coatings does not exceed 12.20 ± 1.95 at % and the thickness of the formed layers slightly depends on the spraying distance and reaches 5.5 ± 0.26 μm. The rate of formation of molybdenum-containing layers during induction-thermal vacuum sputtering reached 0.8–1.1 μm/min.