Journal of Machinery Manufacture and Reliability最新文献

This article discusses a technology that uses pressure as an additional thermodynamic parameter, which, along with the concentration of alloying elements, temperature, and time, creates a space of variable states for the melt. This allows for the transition of the melt into a strongly nonequilibrium state, significantly increasing the number of possible scenarios for transitioning to a solid state compared to traditional technologies. To achieve the set goals, a control system algorithm has been developed, proposing that the crystallization process be managed according to a model in the coordinate space: temperature, pressure, time. Using the alloy V95 as an example, it was established that, by stopping the process at different stages, alloys with varying combinations of structural and, consequently, physicomechanical properties can be obtained.

Based on experimental studies aimed at investigating the microstructure and elemental composition of titanium powders for additive machines, obtained by electrodissolution of ОТ4 alloy metal waste in water, it was shown that the rapid crystallization process of molten ОТ4 in a liquid working medium contributes to the spherical shape of the particles, containing the main elements Ti and Al. Spherical titanium powder materials obtained from the electroerosive dispersion of ОТ4 titanium alloy waste can be effectively used for additive machines.

This article discusses methodological, theoretical, and procedural frameworks for studying complex safety issues within the engineering and technical direction of higher education. Based on an analysis of contemporary scientific literature, conclusions are drawn that relevant approaches include: a comprehensive approach reflecting the interrelationship of social aspects and technical systems in the safety of engineering and technological industries; competency-based and knowledge-based approaches aimed at developing students’ ability to apply constructive knowledge, skills, and abilities in engineering activities when creating new products and systems. Significant for studying safety issues is project-oriented education, the “project engineering” approach, and the application and development of morphological methods in technological systems to ensure the development of flexible (interdisciplinary) and professional competencies in engineering education.

The features of brittle fracture of pistons in an internal combustion engine (ICE) of a combined metal have been determined: aluminum cast alloy reinforced with a bandage insert of heat-resistant cast iron. Fractographic analysis of fractures reveals defects in the fusion of the base metal of the pistons and the embedded bandage ring. The cause of the incident is due to the constraint of significant temperature–force deformations during thermal cyclings of a dissimilar metal with different thermal–physical properties and an unsuccessful shape of the cast iron insert. It is complex in nature, combining a low level of piston design and the manufacturing of reinforced castings, in which, during operation, high temperature stresses occur in the metal of the piston and the embedded part.

The dependence of the reaction rate on temperature and pressure is considered from the standpoint of chemical kinetics, and an attempt is made to explain the increase in friction force after a decreasing load on the contacting surfaces and attaining the minimum with an increase in the sliding velocity. Thermodynamic aspects of the transition state theory and the cases wherein the reaction itself causes resulting deviations from equilibrium are considered.

The results of this study are presented, aimed at justifying, including through experimental methods, the feasibility and prospects of using a high-concentration energy flow (ultrashort pulse laser) for the preparation of surfaces of worn parts for subsequent application of protective coatings by plasma methods. The relevance of solving the tasks related to improving the quality of surfaces processed with high-concentration energy flow has been demonstrated. The results of tests on samples made from traditional materials used in the manufacturing of technological equipment are provided. The influence of the angle of inclination and the power of the ultrashort pulse laser on the roughness of the processed surface is shown. The main research directions, supported by positive results from preliminary experimental data, are formulated. Practical recommendations for using the ultrashort pulse laser for the preparation of surfaces of worn parts are given.

Experimental studies of the temperature and pressure of the lubricant layer between friction surfaces are discussed. A description of the experimental setup is provided, which allows measuring the oil temperature, friction surface temperatures, and lubricant layer pressure.

The magnesium alloy ZK60, which is processed using laser shock processing technology at different laser energies, is examined. Finite element modeling of the laser shock processing technology was carried out to study fretting–corrosion wear of the magnesium alloy ZK60 in an environment simulating body fluids (Hank’s balanced salt solution, HBSS). The mechanical characteristics and fretting–corrosion wear of the magnesium alloy before and after processing using the laser impact hardening technology were investigated. The results showed that the maximum reduction in fretting corrosion wear using the laser impact hardening technology was approximately 73.4%. It is shown that this technology can be applied successfully to reduce the rate of corrosion and fretting–corrosion wear of ZK60 magnesium alloys operating in the HBSS environment.

A project for the development of oil and gas fields, which provides for several systems, including a system for collecting, preparing, and transporting natural and associated petroleum gas through field gas pipelines, is discussed. The main results of the scientific approach to the influence of gas-dynamic forces on the characteristics of a field gas pipeline are presented. The influence of the physical, chemical, thermodynamic, and technological parameters of natural or associated petroleum gas during its movement on the properties of the gas and the characteristics of the field gas pipeline is also considered.

This article discusses the development of a mathematical model and experimental study of a modified design of a radial sliding bearing. The peculiarity of the bearing design is the nonstandard support profile, on the surface of which a polymer coating with a groove is applied. Special attention is paid to accounting for the compressibility of the lubricant material in a turbulent flow regime. The results can be used for further improvement of bearing designs, which will increase their reliability and durability in various industries.