The relationships between stresses and strains in metal porous composites manufactured using 3D technologies, as well as in dispersion-strengthened polymer composites with a hereditary relaxation or creep core, are considered. By applying the Volterra matching principle using the Laplace transform, the effective viscoelastic properties of the composite are calculated in the images. The originals of these characteristics were obtained by inverse transformations using the standard operational calculus method. For composites with a polymer matrix, the Yu.N. Rabotnov method of integral operators is used. As a result, effective stress relaxation characteristics were obtained for metal composites. For polymer composites, an effective law of creep under uniaxial loading was obtained. The theoretical results on creep were compared with similar experimental results.

The microstructure and microhardness of the surface layer of the gearwheels produced by laser cutting of 6-mm-thick 30KhGS sheet steel disks at a laser power of 1200 W and a cutting speed of 20 mm/s are studied. The structure of the heat-affected zone is found to have the following structure: a 6-μm-thick white layer forms on the cutting surface; under it, a structure consisting of martensite and a small amount of retained austenite forms at the side facing a gas jet; at the side facing laser radiation, the structure consists of a sorbite–troostite mixture with spheroidized carbide inclusions. Below, the structure is represented by a sorbite–troostite mixture and martensite grains. The modified layer thickness is 100–250 μm, and the hardness of the layer can reach 500–716 HV.

The effect of laser cutting on the microstructure and microhardness of the cutting surface of gears from a gear train made of structural St3 carbon steel is investigated. The structure in the laser-affected zone is found to differ from the initial ferritic–pearlitic structure and to consist of several layers with a total thickness of about 0.35 mm. The microhardness of this zone can be 420–500 HV, which is 2.5–3 times higher than the initial hardness of the steel. The possibility of combining laser cutting of rolled products of a given thickness with surface hardening is confirmed.

Abstract—The structural features and microhardness in the zone adjacent to the edges of the cut during laser cutting of gear blanks from a sheet of 40Kh steel 6 mm thick were studied. The possibility of combining laser cutting with surface hardening is shown. On average, the hardened surface layer in different sections of the cut has a thickness on the order of 150–250 μm with a maximum hardness approximately equivalent to 46–58 HRC, which is quite comparable to the hardening of 40Kh steel with most surface treatments.

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Аннотация В статье рассмотрено взаимодействие водорода с дефектами кристаллического строения в металлах и сплавах.Приведена классификация водородных ловушек с точки зрения их энергетических уровней.Рассмотрены различные виды взаимодействий водо-родных ловушек, в зависимости от их энергии связи.Изучено влияние водородных ло-вушек на коэффициент диффузии водорода в стали

The influence of adding 10 wt % MoS2 particles to a Litol-24 lubricant on the sliding friction of R6M5 steel on grade 45 steel according to the roller–roller scheme is studied at a load of up to 800 N and a rotation speed of 1500 min–1. The determined general laws of sliding friction are shown not to change in comparison with the previously established ones. The dependences of the frictional force on the normal force (load) have two linear sections, in which the Amonton–Coulomb law is valid. In general, the generalized version of the Amonton–Coulomb law also holds true. The addition of MoS2 increases the lubricant viscosity and the bearing capacity of the lubricant layer. In the load range 510–725 N, the critical load increases by ≈1.6 times and the best antifriction characteristics are achieved.

Two variants of the generalized three-component mathematical model of external sliding friction are proposed. This approach involves the Deryagin molecular friction theory and allows describing the dependence of friction force on load under one or more changes in friction modes caused by complex physicochemical and mechanical processes in the friction contact area. The change in friction is shown to have a piecewise linear character, whereas such parameters of frictional interaction as the differential coefficient of friction, the equilibrium force of molecular attraction, and the molecular component of friction force change in a sigmoid manner.

The sliding friction of R6M5 steel on grade 45 steel in the load range from 0 to 700 N in the medium of a plastic Litol-24 lubricant modified with dispersed graphite particles is studied. The dependence of the frictional force on the normal force is found to have a piecewise linear form with two linear sections. Both classical and generalized versions of the Amonton–Coulomb law are shown to be valid for the materials under study. Graphite particles are found to improve the antifriction characteristics in the load range 442–614 N and to increase the critical load from 390 to 540 N and the bearing capacity of the lubricating layer. A mathematical model is proposed to describe the viscosity of plastic lubricants with dispersed additives.

АннотацияЖС6У в дистиллированной воде и осветительном керосине осуществлялась с учетом таких факторов, как напряжение на электродах, емкость разрядных конденсаторов и частота следования импульсов.Согласно проведенной серии опытов определены предельные значения параметра оптимизации по среднему размеру электроэрозионных частиц, которые составили: для дистиллированной воды -50,4 мкм при ёмкости разрядных конденсаторов 65,5 мкФ, напряжении на электродах 200 В, частоте следования импульсов 200 Гц; для осветительного керосина -58,4 мкм при ёмкости разрядных конденсаторов 65,5 мкФ, напряжении на электродах 200 В, частоте следования импульсов 200 Гц.Проведение намеченных мероприятий позволит решить проблему переработки отходов жаропрочного никелевого сплава и повторное их использование при изготовлении ответственных деталей машиностроения.

Analysis of the deformation processes of both long-known and new polymer, composite and synthetic materials used in building structures, parts of apparatuses, machines, as well as power plants revealed their specific properties.It is established that many similar materials have orthotropy of the structure with simultaneous manifestation of deformation anisotropy or heterogeneity.Induced deformation anisotropy or mechanical inhomogeneity is caused by the dependence of stiffness and strength characteristics on the type of stress state.In previous works of the authors, it has been shown that traditional models of deformation of such materials and their mathematical representations lead to gross errors that are clearly manifested in the calculation of various structures.At the same time, the theories of deformation of composite materials with "complicated properties specially developed for them by other authors in the

Протопопов Евгений Александрович -кандидат технических наук

The results of experimental studies aimed at optimizing the process of spark plasma sintering of powders obtained by electroerosive dispersion of waste heat-resistant nickel alloy ZhS6U in distilled water are presented. Optimal values of pressure, temperature and holding time of spark plasma sintering of electroerosive nickel powders providing a nonporous structure of a heat-resistant alloy with maximum hardness have been established.

The level of corrosion resistance and conditions of corrosion cracking of the bush insert of two-layer oil well tubing fabricated from 5Kh13N2MB martensitic stainless steel are found. The average rate of general corrosion under the conditions of autoclave testing is found, which is used for the evaluation of the service life of tubes. It is found that the fabrication technology of two-layer tubes being used has a negative effect on the corrosion properties of the material of the bush insert.

АннотацияОдной из основных проблем использования вольфрамсодержащих твердых сплавов в настоящее время является высокая стоимость вольфрама.Ввиду высокой температуры плавления существует проблема их переработки для вторичного использования.Одним из перспективных методов их переработки в порошки сферической формы является электроэрозионное диспергирование (ЭЭД).К настоящему времени в современной научнотехнической литературе отсутствуют полноценные сведения об использовании диспергированных электроэрозией частиц сплава Т5К10 в качестве шихты для производства вольфрамо-титано-кобальтовых сплавов и режущего инструменты из них.Для этих целей требуется проведение комплексных теоретических и экспериментальных исследований

The sliding friction of R6M5 steel on grade 45 steel at a load of up to 1400 N under the lubrication conditions of Litol-24 grease modified with zinc and cadmium in an amount of 3 and 2 wt

Sliding friction of 35 grade steel against BRAZh9-4 grade bronze has been studied in an environment of Addinol Zylinderöl Z1500 lubricating oil with dispersed particles of magnesium hydrosilicate (serpentinite) at a concentration of 0.5 and 1 wt %. It has been found that the curves of change in sliding friction parameters have both linear parts and parts approximated by exponential and quadratic curves. The average value of the friction force in the range of normal force [800; 1000] upon addition of 0.5 wt % of magnesium hydrosilicate to the lubricating oil exhibits a 69% decrease, whereas upon addition of 1 wt % of magnesium hydrosilicate, a 26% decrease in this parameter is observed.

АннотацияТест с шестиминутной ходьбой (ТШХ) является одним из простых и доступных методов оценки толерантности к физической нагрузке.Вместе с тем до конца еще не изучены вопросы представления и интерпретации его результатов.Известно, что в случае отсутствия формальных законов явления, может быть применен метод анализа размерности.Этот метод, впервые предложенный Фурье и развитый в работах Рэлея, Прандтля, Бакингема и др., довольно успешно применяется в физике, химии, технике, экономике и крайне редко в биологии и медицине