One of the most difficult tasks of the analytical control of copper ores is the determination of the mineral forms of copper. Currently, for this purpose, iodometric and atomic absorption methods are used with preliminary leaching of various mineral forms. The disadvantage of those methods is a rather complicated sample preparation procedure and significant time of analysis. The most universal method for determining the mineral composition of solid samples is the X-ray diffraction method. However, significant variations in the phase composition of copper ores, overlapping reflections of different phases, the presence of an amorphous phase and structural defects necessitate the development of special approaches. In this work, the presence of an amorphous phase is taken into account by direct calculation of the mass fractions of crystalline phases by the G-factor method. The total copper content is determined by the X-ray fluorescence method. Methodological approaches based on using only X-ray methods are proposed, which exclude the procedures of leaching and dissolution of samples and provide determination of primary and secondary copper sulfides using calibration characteristics (3 min), and gaining data on the complete phase composition at the stage of routine analysis (10 – 15 min) and for research purposes (15 – 20 min). 

The use of artificial neural networks (ANNs) is considered justified when studying the problems that do not have a generally accepted solution algorithm. One of such problems in X-ray fluorescence analysis (XRF) is a control of the metal content in atmospheric air and air of the working area. Determination of the calibration characteristics is raveled by the lack of standard samples of the composition of aerosols collected on the filter. To solve this problem, synthetic calibration samples (CS) were manufactured as a thin organic film containing a powder material of the known chemical composition. The weight of the film samples varied within a range of 40 – 155 mg to simulate different aerosol loading of the filters and the content of components in them changed 20 – 200 times which corresponds to the samples of real aerosols. The possibility of modeling a nonlinear calibration multivariable function using artificial neural networks was evaluated in analysis of 38 film calibration samples (from 40 to 100 mg). The structure of the neural network, activation functions, learning algorithms have been investigated. Modeling was performed using an academic version of the BaseGroup Deductor analytical platform. It is shown that implementation of the back propagation of errors leads to much higher values of the error of analysis compared to the error of the regression calibration functions, whereas the Resilient Propagation algorithm provides the smallest values of the error of vanadium determination (S_r) in the calibration samples of aerosols. The range of low content of the elements in the training set is determined with a greater error compared to high content range, and therefore, the sigmoid activation function leads to unsatisfactory accuracy of the analysis results, and preference should be given to hyperbolic tangent (tanh).

Detection of biologically active components in mixtures of complex composition which include biological fluids (blood, urine, etc.) is the most difficult problem of the analytical chemistry and requires the use of modern highly informative research methods. One of the most effective and universal ways to study the structure of unknown substances is the method of liquid chromatography- high resolution mass spectrometry that combines the possibility of highly selective separation of the mixtures under study, the reliable detection of unknown substances and high sensitivity of the procedure. We propose a method for the simultaneous extraction of highly polar biomarkers of nitrogen mustard — N-triethanolamine (TEA), N-ethyl diethanolamine (EDEA) and N-methyldiethanolamine (MDEA) — from urine with subsequent determination by HPLC and detection by high resolution tandem mass spectrometry. The mass spectra of fragmentation of protonated molecular ions of TEA, EDEA, and MDEA have been studied and possible structural formulas of the fragment ions are given. The sample preparation of urine and mass spectrometric detection in the multiple reaction monitoring mode were optimized. The five-fold dilution with deionized water was chosen as a method of urine sample preparation for analysis. Separation of the components was performed in the reversed-phase chromatography mode with retention times for TEA, EDEA, and MDEA of 2.00, 2.05, and 1.92 min, respectively. The time required to complete all steps of the urine sample analysis did not exceed 25 min. The detection limits in urine were 1 ng/ml for TEA and 2 ng/ml for EDEA and MDEA. The developed approach provides determination of the fact of application of specific nitrogen mustard in enquiry of possible exposure of living organism to the blister agents.

The microstructure-sensitive acoustic parameters (MSA parameters) of metal of the object under control are determined using measurements of the propagation time of bulk elastic waves of the ultrasonic range by the echo-pulse method. The structural features of the metal are thus evaluated not only in the surface layer, but also throughout the entire volume. We present the results of practical application of the MSA-parameters to estimation of the deviation of the velocity ratios of longitudinal and shear waves relative to the «basic» state with known strength characteristics. A correlation of the MSA-parameters with variations in the elastic moduli of metals attributed to modification of their microstructure is discussed. The generalized values of the ratios of wave velocities for steels of the same group are used in calculations to characterize the «base» state. It is shown that when calculating the MSA-parameters for a certain kind of construction steel, it is possible to use the averaged ratios of the velocities measured for quasi-isotropic reference samples made of the same type of steel. The generalized baseline ratios of the longitudinal and shear wave velocities are determined for the samples made of carbon steel, low-alloy, and alloyed steels. We present experimental evidence of using MSA-parameters to detect microstructural changes in metal samples and accompanying changes in their strength characteristics that occur during changes in modes and conditions of welding and heat treatment. A comparative analysis of the MSA parameters with the values of the mechanical properties and parameters of the crack resistance of the metal is carried out. It was shown that the accuracy of measuring the MCA parameters provided by modern hardware significantly exceeds changes in them occurred under significant deviations of the strength characteristics. The experimental results obtained clearly indicate that the MSA-parameters can be successfully used to improve the methods of quantitative non-destructive assessment of the features of metal microstructures

Aluminum alloys with electroplated coatings and copper plated in particular gained multiple applications. However, pre-zincate treatment often fails to provide the desired adhesion of the coating. We present the results of studying the effect of the electrolyte composition on the adhesion and other properties of the coating-base system. It is shown that an electrolyte with a reduced content of sulfuric and phosphoric acids can be used for anodizing and the oxide films formed during anodizing are stable in the usual copper-plating sulfuric acid electrolyte which eliminates contact exchange and increases adhesion. The use of a modern scratch-test method provides numerical determination of the values of adhesion of copper coatings. The adhesion value depends on the surface porosity of the oxide film and on the type of anodized alloys. The results can be used to improve the technology of applying copper coatings, both as an independent coating and as an underlayer in multilayer coatings.

Determination of the porosity, structural characteristics of pores, and gas pressure in closed pores is the most important part of assessing physical and mechanical properties of materials. The internal pressure inside the pore can be used in estimating the level of strength reliability of the porous volume of the product to optimize the technological processes of product manufacturing, control their structure and properties, and avoid the formation of cracks at the boundaries of the particles consisting the material. We present a method for calculating the internal pressure in a spherical pore that has arisen in the material of a product obtained using powder metallurgy or additive technologies. The proposed procedure for measuring internal pressure in a pore consists in application of an external pressure to the product, measurements of the displacements of the points on the pore surface, and calculation of the internal pressure from the difference between the displacements. In this case, the known solutions of the problem of the theory of elasticity regarding the deformation of a spherical cavity located in the center of a spherical hollow ball are used. The results obtained can be used to assess the properties and structure of the products obtained by additive technology and methods of powder metallurgy, as well as to improve the technology of their manufacture.

An analytical approach which provides conservative estimates of the probability of fatigue brittle fracture of structural components of technical systems taking into account the scatter of the initial dimensions of crack-like defects described by the exponent probabilistic distribution is presented. The operational loading is considered both as deterministic (with loading cycles of constant amplitude and frequency) and random (stationary narrow-band Gaussian random loading) process. The crack growth kinetics is described by the modified Paris equation that takes into account the stress ratio effects. The parameters of the Paris law are considered deterministic values. An example of the assessment of the probability of fatigue failure of tubular structural component with an axial crack on the inner surface of a tube subjected to internal pressure is presented. A comparative analysis of the results obtained with and without taking into account the random nature of the operational loading is carried out. It is shown that neglection of the random nature of the operational loading leads to non-conservative estimates of the fatigue failure probability, which may differ by an order of magnitude compared to the calculation data obtained with allowance for the stochastic nature of the loading process. The developed method can be used in the implementation of probabilistic and risk-based approaches to ensuring strength, service life and safety of technical systems in real operation conditions and in adjusting standard operation programs in terms of choosing the frequency and scope of non-destructive testing.

The results of the Rehbinder effect manifestation during testing of superalloys in contact with corrosive media containing Na₂SO₄ + NaCl are discussed. We present the experimental study of the effect of salts containing chlorine and sulfur on the mechanical properties and long-term strength of single crystal and powder nickel-based superalloys at high temperatures. The practical value of the work is associated with the possible operation of gas turbine parts in conditions of ingress of the particles containing chlorine, sulfur and sodium into the flow path. A simplified (compared to a previously used) procedure of testing wrought alloys for long-term strength in molten salts is developed. A comparative study of the mechanical properties and long-term strength of a single crystal superalloy in the initial state (previously damaged by corrosion of different duration) and being in contact with salts during testing is carried out. Due to the large scatter of experimental data, the method of lower envelopes has been proposed and implemented to determine the guaranteed values of the long-term strength. It is shown that the guaranteed values of the long-term strength at different temperatures and test durations can decrease by 2.5 – 5.0 times in the presence of salts. Metallographic studies of the nature of damage and destruction of samples are carried out. The revealed decrease in the long-term strength of heat-resistant alloys in contact with salts is interpreted as the Rehbinder effect and not as a manifestation of the effect of stress corrosion cracking. A methodology for using the obtained test results with a duration of up to several thousand hours in highly aggressive environments is proposed to predict the long-term strength in relation to long-term operation (tens of thousands of hours) under conditions of relatively low salt loads.

A review of the existing methods of accelerated abrasive wear tests is presented. The shortcomings of the technique implemented on an IM-01 installation of the VISKHOM design, as well as the Brinell-Howarth technique for laboratory studies, in which a powder abrasive is used are discussed, e.g., a problem of a uniform distribution of a free-flowing abrasive material over the surface of the contact zone, as well as problems of ensuring the stability of the supply of the abrasive material during the experiment. The goal of the study is to develop a methodology for comparative assessment of the wear resistance, excluding noted shortcomings. The tests were carried out on an M-1 installation using plate specimens 60 × 40 × 3 mm. The abrasive material used was a radial flap wheel 150 – 220 mm in diameter (width 30 mm, bore diameter 30 – 40 mm). The degree of wear was determined by a decrease in the mass of the sample by weighing on a balance with an accuracy of 0.1 mg before and after testing. The test results were considered as a relative wear resistance ε equal to the ratio of the wear resistance of the test specimen to the wear resistance of the reference one. The use of relative wear resistance makes it possible to increase the accuracy of the results obtained due to elimination of the influence of natural changes in external parameters that determine the intensity of wear during the test. The developed installation provides significant shortening of the accelerated comparative test (8 min) compared to 40 min on an IM-1, the structure and grain size of the working fluid, the constancy of the load in the contact zone and the speed of interaction between the sample and the tool being the same. Flap wheels of various grain sizes provide application of the device to a wide range of tasks without preliminary grinding of the samples and necessitate only their preliminary cleaning from slags and large particles after applying wear-resistant coatings.

The necessity of developing certified reference materials (CRM) for the composition of mineral oil with a certified value of the mass fraction of water, traceable to the State Primary Standard of units of mass fraction and mass (molar) concentration of water in solid and liquid substances and materials GET 173–2017 is revealed proceeding from the review of standardized methods for determining the quality of mineral oils and approved types of reference materials (CRMs). Mineral hydraulic oil MIL-H-5606 of CONOSTAN series manufactured by SCP SCIENCE (Canada) was chosen as the CRM material to control the accuracy of the results of water determination in mineral oils using IR spectrometers. A procedure for reproducing the mass fraction of water in a mineral oil using a standard installation based on coulometric titration according to Karl Fischer method from the composition of GET 173–2017 has been developed. The relative expanded uncertainty (at k = 2) of measurement results of the water mass fraction in mineral oil is 7.1%. The requirements to the metrological characteristics of CRM were formulated: the interval of permissible certified values, the limits of the permissible values of the absolute error at P = 0.95, and the permissible value of the absolute expanded uncertainty at k = 2. The choice of the method of packaging and conditions of CRM storage were analyzed. Taking into account the consistency of the measurement results of the water mass fraction obtained by coulometric titration according to Karl Fischer method and using a Fluid Scan infrared spectrometer manufactured by Spectro Inc., USA, the applicability of CRMs for metrological support of express IR spectrometers was demonstrated.