Determination of impurities in Ta- and Nb-based materials is a necessary operation in supporting technological processes. The existing approaches involve the transfer of a sample into a solution with subsequent isolation of impurities. This procedure is rather complicated and takes a lot of time. For this reason, it is of interest to study the possibilities of direct analysis of solid-phase samples of materials, e.g., X-ray fluorescence analysis (XRF). The usual scheme of X-ray fluorescence analysis, which involves the experimental construction of calibration characteristics for each element to be determined, requires using a large number of reference samples containing a rather wide range of impurities. We present the results of preliminary characterization of samples of technical-grade tantalum and niobium and products on their base. It is shown that for starting materials, only a significant absence of impurities can be determined using XPA, but even for sintered niobium hydride and Ta powder, XPA can be used as a method for rapid assessment of the composition. A SPECTROSCAN MAX GVM crystal-diffraction spectrometer can be used for analysis and a standard software that implements the fundamental parameter method (FPA) can be used for calibration. In this case, the obtained values of the content of impurities may differ by 1 – 2 orders of magnitude from the reference values. However, such an accuracy is often enough to correct technological processes. The limits of detecting impurities by XRF in Ta- and Nb-based materials are revealed: for elements determined by K-series (from Ti to Co), the detection limits lie in the range from 30 to 60 ppm, whereas for the elements determined by M-series (Ta) the detection limit is approximately 200 ppm and for L-series (Nb) the detection limit is in the range from 100 to 150 ppm.

A method of gas chromatography-mass spectrometry (GC-MS) in combination with pre-concentration on a sorbent with BPA molecular imprints (dosage of sorbent — 50 mg, sorption time — 10 min, pH — 3, desorption with methanol) is used to determine bisphenol A (BPA). The sorbent extracts about 96% of BPA from aqueous solutions with a single sorption and is characterized by a high imprinting factor reaching 7.1. The samples of soils of urbanized territories, as well as typical chernozems and residual carbonate chernozems outside the large cities of the Voronezh region were studied. The limit of BPA detection was 0.07 μg/kg (in terms of dry soil), the range of the linearity of the calibration graph was 0.3 – 35 μg/kg. Determination of bisphenol is hindered by soil contamination with petroleum products, which can be eliminated by washing with heptane. It has been revealed that pH of soils has a significant effect on the BPA migration of along the soil profile. The concentration curves of the BPA distribution over the soil profile up to a depth of 1 m were plotted. The maximum BPA concentrations in the soils of urbanized territories depend on the contamination of the territory with polymer waste. The maximum BPA concentrations (29.84 μg/kg) were determined at a depth of 20 cm in samples taken near the landfill of municipal solid waste. At other points within the city limits, the maximum concentrations range within 5.38 – 8.77 μg/kg. Outside the city of Voronezh, the mobility of BPA increases in more alkaline typical and residual-calcareous chernozems and significant concentrations of the pollutant were found at a depth of 50 – 80 cm. The developed scheme can be applied to targeted screening and monitoring of the BPA content. The method can be used for BPA determination in soil horizons for various soil types, meteorological conditions (precipitation, annual temperature regime), and contamination of the territory (the presence of unauthorized landfills, MSW landfills, sewage treatment facilities near the sampling point).

The study is aimed at developing highly sensitive methods of laser analytical spectroscopy. The physical mechanisms of forming useful signals (selective ionization signal and cavity ring-down signal) were identified that provided registration of parameters of atomic and aerosol systems in the intensive pulsed laser field. High-sensitive laser methods of laser resonance ionization spectroscopy in vacuum, laser-enhanced ionization spectrometry in flame, and cavity ringdown laser absorption spectroscopy (CRLAS) are used for the determination of ultra-small concentrations of atoms in different phase states of the substance. Samples of aqueous standard solutions and solid metals of s (Li, K, Na, Ca, Cs), p (Al, In), d (Cr, Mn, Fe, Co, Ni, Cu, Ag, Au, Pt, Zn, Hg), f (Yb) elements, aluminum alloys, especially pure solvents, crystals (NH4F, NaF), semi-conductor materials (GaAs, Si) and various aerosols of salts (NaCl, CsCl, NaI, NaF, KCl AgNO₃), chemicals, organic dyes, alloys, soils and rocks were studied. The new mechanisms of getting free particles are revealed and new methods increasing the efficiency of atomization, selective ionization and excitation of atoms in systems «flame», «rod – flame», in atomizer «graphite – furnace» are proposed. The particle size distribution of aerosols formed under the impact of high-power laser radiation on the surface of a solid sample has been studied. The dependence of the absolute concentration of aerosol particles on their size has been determined. Aerosol extinction coefficients and extinction efficiency have been measured using intracavity laser spectroscopy. For the first time new parameters of aerosols are revealed by physical and chemical properties of aerosol plumes from solid surfaces and aerosols of salt of metals and organic aerosols. Methods of additives and calibration curve were used to examine the effects of the matrix on the analytical signal of the studied atoms.

Bronze alloys, due to their resistance to mechanical abrasion and high corrosion resistance, are used for the manufacture of machine parts and mechanisms that are subject to friction during operation. We present the results of studying the effect of shock-wave loading on the structure and properties of bronze alloys of grades BrAZh9-4 and BrAMts9-2. Shock-wave loading experiments were carried out by throwing the flyer plate onto cylindrical samples and compressing by a sliding detonation wave. The method of throwing a flyer plate accelerated by the energy of an explosion is often used to determine the spall strength of materials and the method of compression by a sliding detonation wave is used to create a large dynamic pressure inside the material. It is shown that at a throwing speed of a flyer plate of 2.4 km/sec, the impact pressure of the plate with the sample is 15 – 16 GPa, which exceeds the bronze shear strength. Under indicated loading conditions, the hardness of bronze increases by 53 and 25% for BrAZh9-4 and BrAMts9-2, respectively. Studies of the microstructure using scanning electron and optical microscopy revealed multiple cracks and micropores present on the surface of transverse sections forming a zone of spall fracture and areas turning into bands of localized deformation. Moreover, it is shown that when the samples are loaded with a flyer plate in a clip and without it, a greater number of cracks and shear areas are observed. Compression by a sliding detonation wave with a different amount of explosive charge revealed small defects present in the structure at the grain boundaries. The results obtained can be used to developed technologies for modifying and restoring the properties of bronze parts subject to shock-wave destruction.

We present the results of measuring the volume of polyvinyl alcohol polymer granules crosslinked with epichlorohydrin in water and in aqueous solutions of KCl, MgCl₂ and their mixtures, obtained by optical micrometry, and consider the main sources of errors in the measurement errors. The purpose of this study is to analyze and evaluate the effect of the main sources of errors on the accuracy of determining the relative volumes of granules, as well as to search for techniques that can minimize the resulting measurement errors. The diameters of the granules were determined using specialized software implementing machine vision algorithms from the images obtained by optical microscopy. Their volumes were calculated using the formula for the volume of the ellipsoid of revolution. The maximum accuracy of volume determination is known to be achieved when the measured granule has a sphere shape. It is shown that deviation from this shape, for example, in case of an ellipsoid, gives errors in determining the third axis of the ellipsoid, invisible in the image, which creates an error in determining the relative volume of the granule. The instrument error is determined and a statistical estimate of the error attributed to the non-sphericity of the granules is given. It is shown that a typical instrument error in determining the relative volumes of granules is 0.4%. The non-sphericity of the measured granules increases the measurement error up to 3.5%. The error for a single granule can be reduced to 2.3% by combination of methodological techniques and statistical processing of the results, whereas and for an ensemble of at least 5 granules — up to 1.5%. The reproducibility of the properties of polymer granules in cyclic measurements was studied. It is shown that the degree of swelling the granules is reproduced with an error of 1%, which allows the sensor to be used repeatedly. The results obtained can be used in experiments and data processing for analytical applications.

The impact of residual stresses in a DN850 pipe (steel 10GN2MFA) with austenitic cladding, welding stresses in the mounting annular seam of the pipeline, and residual stresses arising in a curvilinear branch DN350 (steel 08Kh18N10T) during manufacture by plastic deformation on the opening and stability of through cracks is considered. Calculations of residual stresses are performed using the finite element method (FEM). It is shown that residual stresses cause a change in the size and shape of the outflow channel, the coolant flow rate, and the value of the J-integral at the crack tip. In case of short cracks and relatively low operating stresses, the crack edges can close on the inside of the pipe wall due to the action of residual stresses thus leading to a decrease or cessation of the leak. A reversed effect of residual stresses on extended cracks is observed at rather high operating stresses: change in the shape of the outflow channel (an increase in the opening of the crack edges on the outer surface of the pipe) leads to a decrease in the friction of the coolant flow against the crack edges and, hence, to an increase in the leak volume. The results of testing full-scale models of elements of a straight section of the pipeline with a welded seam and a curvilinear branch DN350 with artificially created defects by internal pressure and bending moment are presented. It is shown that local through cracks develop from initial defects, which remain stable at maximum design loads (normal operating conditions plus maximum design earthquake) which matches the calculation results and meets the requirements of the applicability of the concept of «leak before break».

The residual life of the runners of hydraulic turbines in the presence of operational defects is estimated. The main problems of the operation of hydraulic turbines associated with technological defects and exhaustion of the standard resource are described. The main requirements for initial data to be used in estimation of the residual resource and the requirements for predicting the residual resource of runners based on the results of surveys and analysis of their technical condition are specified. We have classified and briefly described the applied approaches and techniques used in estimation of the residual resource. The main damaging factors affecting the residual life of the runners are revealed: deformation aging of the metal, cavitation, corrosion and fatigue damage to the elements of runners. The most characteristic defects are divided into three groups: zones of cavitation erosion; corrosion-fatigue cracks; and weld defects. Particular attention is paid to corrosion-fatigue cracks identified using flaw detection. The mechanism of crack formation and the most probable location of the cracks in the runner are shown. Statistical data on the number of cracks at the onset of the runner operation and at the time of shutdown maintenance are presented. The main statistical parameters of the sample and the parameters of crack size distributions including the distribution law are determined. The distribution law is exponential for the crack length parameter; whereas for the crack opening width it is log-normal. The revealed multidirectional cracks are located at the surface, subsurface or inner layer of the metal. They arise from operational defects (ulcers, craters, undercuts or delamination) and grow during operation of the turbine units. We also present the design schemes of elements with cracks used for quantification of resources according to the criteria of fracture mechanics. The results of calculations for static and dynamic crack resistance are presented as the dependence of stress intensity factors on the crack size. The levels of the total accumulated damage to the runners, the values of the residual life at the stage of crack nucleation and development were determined for 11 hydraulic units in the «start-stop» and «working» cycles. The main conclusion is that the total operating time of the hydraulic turbine runners significantly exceeds the standard operating life, while the residual resource is insufficient for a further period of long-term operation.

A high-strength aluminum alloy 1933 being distinguished by good physicomechanical properties and high manufacturability is widely used in the most critical power aircraft structures, e.g., in a modern AN-148 SSJ aircraft. The alloy is used in production of various parts of articulated joints, thus making study of the durability of the alloy in a complex stress state a relevant goal. We present the results of static and dynamic tests of structurally similar samples (of two types) manufactured according to serial technology and corresponding to the shape of real eyelets of the airframe slats. Preliminary fatigue tests of standard samples (a strip with a hole) were performed to obtain the refined characteristics of the alloy in the T3 state. To analyze the mechanical behavior of the alloy with a different amplitude-frequency character of loading, the asymmetry of the loading cycle (R = 0.1; 0.2; 0.5; 0.6; 0.76; 0.82) and exposure frequencies (10, 60, and 100 Hz) were varied. In is shown that an increase in the average stress of the loading cycle reduced the number of cycles before the destruction of the eyelets: a 2-fold increase in the average stress resulted in a drop in fatigue life by two orders of magnitude (for an amplitude of 5 kg/mm²).