During the synthesis of isopropyl alcohol by the acetone hydrogenation reaction, it is necessary to control the content of impurities in the hydrogen used, since its purity determines the quality of the product, and impurities of CO and CO₂ are catalytic poisons for this reaction. At the «Omsky Kauchuk» plant, the purity of hydrogen is determined by gas chromatography using two different chromatographs — laboratory and flow. A comparison of the results of the parallel determination of hydrogen purity revealed a discrepancy of about 10 % wt., while the flow chromatograph did not detect impurities of CO and CO₂, the content of which, according to the laboratory chromatograph, was 0.10 and 0.016 % wt., respectively; the nitrogen content was significantly underestimated. Based on the conducted research, it was found that the sorbent of the nozzle column of the flow chromatograph is not suitable for the determination of CO₂ that distorts the results of hydrogen determination. In this regard, other options for nozzle columns with a CO₂-selective sorbent are proposed for use with a flow chromatograph, and it is also necessary to periodically warm up the column to remove volatile contaminants.

The processes of Pb and Cd atomization in seawater samples in a rapidly heated (heating rate of 10 °C/msec) graphite furnace with ballast are studied. A method for determination of Pb and Cd in seawater samples using a Zeeman electrothermal atomic absorption (ETAA) spectrometer with tantalum ballast in a rapidly heated graphite furnace without preliminary sample preparation and/or addition of chemical modifiers is developed. The experiments were performed using seawater samples from the Baltic and Black Seas and a model seawater solution with a salinity of 35 g/liter. When the graphite furnace is heated, sample vapors condense on the relatively cold ballast, and then the sample repeatedly evaporates (re-evaporates) from the ballast, when it is heated by the radiation of the furnace walls, into a heated analytical cell. The shift of the atomization process to the region of steady-state and high furnace temperature and the decrease of background absorption during atomization help to decrease the chemical and matrix spectral effects on the analytical signal. To compensate the systematic error of element determination, the standard addition method adapted to the spectrometer conversion function was used. The analytical and metrological characteristics of the technique were established: characteristic masses of Pb — 2.2 pg, Cd — 0.17 pg and characteristic concentrations of Pb — 0.44 μg/liter, Cd — 0.034 μg/liter, detection limits of Pb — 0.20 μg/liter, Cd — 0.02 μg/liter, determination limits of Pb — 0.50 μg/liter, Cd — 0.05 μg/liter, random and systematic components of the error of determination of elements in seawater samples are no more than 10%.

Metrological support for the development of a standard reference material of a feed additive with certified mass fraction of fluorine for the needs of the agro-industrial complex is presented. To select the method of sample preparation, samples of limestone flour and artificial mixtures based on it, as well as feed tricalcium phosphate, were analyzed. It was found that the distillation of fluorine in the form of hexafluorosilicic acid from a solution of sulfuric acid with quartz sand ensures complete extraction of the analyte. Based on the results of the ionometric determination of fluorine (10 measurement series with 5 parallel determinations each), the metrological characteristics of the proposed technique were calculated — the repeatability index, the precision index and the extended measurement uncertainty. It is shown that the proposed technique can be used to certify the material of a feed additive based on mineral raw materials in the range of the mass fraction of fluorine from 0.01 to 0.2%, with a relative expanded uncertainty of 4.2%. The measurement technique (MI 243/20–2024) has been certified and entered into the Federal State Information System «Arshin» under No. FR.1.31.2025.50773. In accordance with the developed technique the batch of tricalcium phosphate samples with a natural fluorine content was certified: fluorine mass fraction was 0.120% with extended measurement uncertainty of 0.006%.

One of the main factors hindering the application of high-dense electropulsing technology is the lack of commercial devices to record the temperature of wrought semi-products and billets under conditions of ultrahigh heating rate and ultrashort annealing time. The paper presents the data on the control of temperature and duration of the stages of heating and cooling of rectangular plates with a thickness of 1 mm and gauge length of up to 92 mm out of cold- and cryo-rolled sheets of the 1560 (Al – 6Mg – 0.6Mn) and 1965 (Al – 8Zn – 2Mg – 2Cu – 0.1Zr – 0.2Sc – 0.1Mn) alloys during a single exposure to millisecond pulses with a current density of up to 90 kA/mm². The temperature changes were recorded using digital thermographic camera THT-600 with a frame rate of 50 Hz. It was found that the temperature measured in the central sample volumes coincides well with the calculated one under heating up to 200°C and weakly depends on their length. The temperature distributions over the width and length of the plates are heterogeneous, and the temperature gradient decreases with their length. The detection of volumes with an increased temperature along the longitudinal edges of the samples was originated by the elecropulsing skin-effect, and those with a reduced temperature near the boundaries of the treated zone were due to intense heat outflow through capture-current traps. The results can be used to improve methods of on-line temperature control of aluminum semiproducts under electropulsing treatment.

With increasing operating speeds and contact loads of structural elements, it is necessary to increase the operational life of friction units, which can be ensured by improving the physical and mechanical properties of the contact surfaces. The paper presents the results of investigations of the properties of coatings formed from nanostructured composite powders of the Ti/TiO₂ system by microplasma spraying. Experimental data on the synthesis of nanostructured powders based on a titanium matrix reinforced with titanium dioxide nanopowders are presented. PTOM-1 titanium powder with a fraction of less than 90 μm and nanoscale titanium dioxide powder with a fraction of 80 – 200 nm were used as starting materials. Mixtures of starting materials with variable TiO₂ content were subjected to preliminary homogenization and subsequent mechanosynthesis. When studying the morphology of the synthesized powders, it was revealed that the shape of the particles is inherited from the matrix powder, and with an increase in the content of the reinforcing component, the surface of the composite powder is more densely reinforced with particles of TiO₂ nanopowder. The determination of the fractional composition showed that the maximum volume fraction of particles (62. 5 % wt.) it corresponds to a size of 10 – 40 μm. Scanning electron microscopy of transverse microspheres revealed that there are no through pores in all coatings. With an increase in the titanium dioxide content to 24 %, porosity increases significantly, and there is also a detachment of the coating material from the substrate. A study of the microhardness of the sprayed coatings showed that the hardest coating (on average 985 HV) was obtained by spraying a synthesized powder with a titanium dioxide content of 16 % by weight. The results obtained can be used to extend the life of, for example, titanium alloy ball valves used in autoclaves for the mining industry.

Accelerators of negative hydrogen ions and deuterons are widely used, for example, in the field of medicine. The particle beam is removed from the accelerators by recharging ions as they pass through a thin carbon foil. The paper presents the results of a study of the longevity of stripper foils. Carbon foils with a thickness of 1 – 4 μm obtained on a glass substrate by vacuum arc sputtering of graphite rods were studied. During the experiments, a laboratory setup was used that simulates the effect of a beam of negative hydrogen ions (energy 18 MeV) using an electron beam (energy 10 keV). The samples were irradiated with a stream of electrons, while each sample retained its integrity. Before and after irradiation, the foil surfaces were analyzed using atomic force microscopy. It was found that irradiation changes the morphology of the surface (roughness parameters deteriorate). The method of electrostatic force microscopy revealed a noticeable difference between the irradiated and non-irradiated parts of the foil not only in thickness, but also in electrical conductivity. The obtained results and the developed research method can be used for prompt changes to the foil forming technology to increase their service life.

Predicting the failure-free operation of petrochemical reactors is an important task that ensures the safe functioning of the petrochemical industry, but in the case of deformation-free brittle failure, it is impossible to make an adequate forecast based on the results of regulated technical control. One of the sources of such failure is hydrogen embrittlement. To solve the problem of forecasting without producing large-sized cuttings from the walls of the equipment, a comparison was made of the mechanical properties of samples cut from the walls of a destroyed petrochemical reactor after long-term operation and samples made from a sheet of the same steel grade and saturated by the cathodic polarization method to the same concentration that was measured in the walls of the studied reactor. The thickness of the sheet metal from which the walls were made was equal to the thickness of the sheet from which the model samples were made. The samples were cut along and across the rolling direction. A comparative study of the behavior of identical model and «operational» samples was conducted, taking into account the development of operational damage, the direction of cutting out standardized samples for mechanical isothermal tests, and the time of sample curing after hydrogenation. A regulated calculation of the residual life of the reactor was carried out based on the mechanical characteristics of the samples cut out from it. A fundamental difference in the mechanical characteristics of the model and «operational» samples was found. The strength and yield strengths of the model samples do not change, while those cut out of the reactor are 30% less than the original ones. This difference does not allow using the saturation of model samples by the cathodic polarization method to predict hydrogen degradation of steel elements of petrochemical equipment. The insufficiency of the regulated non-destructive testing methods in technical diagnostics is shown, since they do not take into account the possibility of forming deformation-free hydrogen cracking of the equipment walls. It is shown that the methodology for the regulated calculation of the residual service life carried out during the examination, both on the basis of the actual strength properties of samples cut from the equipment in operation and using the mechanical characteristics of model hydrogenated samples cut in different directions relative to the rolling direction, requires revision.

The results of a study of the creep of polymethyl methacrylate (PMMA) under cyclic loading are presented. The viscoelastic behavior of PMMA was analyzed under normal operating conditions, before the onset of material damage processes. Creep during continuous deformation is a superposition of two processes: the creep acceleration due to a stress increase and its deceleration over time. During an instantaneous increase of load, only the first process takes place, and during an exposure under constant load, only the second. For each of them, equations of state for viscoelasticity are obtained that relate the acceleration of viscous deformation to the rates of elastic and viscous deformation and to the current level of elastic deformation. These equations are applicable in the stress range from the creep limit to the forced elastic limit, as well as during recovery after complete unloading. Since the equations do not explicitly include time and accumulated viscous strain, they can be used for a process with an arbitrary law of growth of strain or stress. Based on the results of cyclic tests with different rates of deformation at the stages of loading and unloading, equations of state were obtained for various combinations of values and directions of rates of elastic and viscous deformation. These equations were used to model the viscous deformation of PMMA according to a given law of the elastic deformation change. Comparison with experiment confirmed the high accuracy of the modelling. A number of successive stages of viscoelastic deformation have been identified depending on the load level: elastic at stress below the creep limit, instantaneously viscous, viscous and viscoplastic. At the first stage, viscous deformation does not increase, at the second stage it increases only with increasing load, at the third stage it also increases during the holding. When reaching the viscoplastic stage, irreversible deformation accumulates, which persists after the return is completed.

This article deals with the model for applying the 3-parameter Weibull distribution to describe the tensile strength of a bundle of parallel fibers (complex thread). This is important because high-strength fibers are usually produced in the form of strands rather than single fibers. For modelling the fiber bundle, fibers with a deformation diagram similar to linear were selected: carbon, glass and aramid (Kevlar-49). The test data of single carbon and glass fibers were obtained by F. Mesquita and colleagues, and the authors’ data obtained from tests of single Kevlar-49 fibers were used to model the aramid fiber bundle. The test data of single fibers of different types were divided into equal ranges of destructive stress and the number of fibers whose strength fell within a given range of values was calculated. The use of a 2-parameter Weibull distribution to predict the strength of reinforced plastics suggests the possibility of accumulation of breaks from the very beginning of deformation, which further leads to the prediction of the appearance of a cluster of fiber breaks of infinite size in the composite under any load, which contradicts observations. It is shown that the 3-parameter distribution better describes the results obtained, and does not require the assumption of fiber destruction at zero voltage. It was found that in the case of glass fibers, destruction begins almost from the start of loading, and the two-parameter Weibull distribution describes their destruction well.