A review of publications regarding detection of non-metallic inclusions in metal alloys using optical emission spectrometry with single-spark spectrum registration is presented. The main advantage of the method - an extremely short time of measurement (~1 min) – makes it useful for the purposes of direct production control. A spark-induced impact on a non-metallic inclusion results in a sharp increase (flashes) in the intensities of spectral lines of the elements that comprise the inclusion because their content in the metal matrix is usually rather small. The intensity distribution of the spectral line of the element obtained from several thousand of single-spark spectra consists of two parts: i) the Gaussian function corresponding to the content of the element in a dissolved form, and ii) an asymmetric additive in the region of high intensity values ??attributed to inclusions. Their quantitative determination is based on the assumption that the intensity of the spectral line in the single-spark spectrum is proportional to the content of the element in the matter ablated by the spark. Thus, according to the calibration dependence constructed using samples with a certified total element content, it is possible not only to determine the proportions of the dissolved and undissolved element, but also the dimensions of the individual inclusions. However, determination of the sizes is limited to a range of 1 – 20 µm. Moreover, only Al-containing inclusions can be determined quantitatively nowadays. Difficulties occur both with elements hardly dissolved in steels (O, Ca, Mg, S), and with the elements which exhibit rather high content in the dissolved form (Si, Mn). It is also still impossible to determine carbides and nitrides in steels using C and N lines. The use of time-resolved spectrometry can reduce the detection limits for inclusions containing Si and, possibly, Mn. The use of the internal standard in determination of the inclusions can also lower the detection limits, but may distort the results. Substitution of photomultipliers by solid-state linear radiation detectors provided development of more reliable internal standard, based on the background value in the vicinity of the spectral line. Verification of the results is difficult in the lack of standard samples of composition of the inclusions. Future studies can expand the range of inclusions to be determined by this method.

The flow-injection determination of boric acid with conductometric detection in technological environments of the primary circuit of WWER-type nuclear power plant is described. The method consists in periodical dosing a fixed sample volume into the flow of the mannitol solution. As a of the Formation of an anionic boric acid complex with mannitol and equivalent amount of hydroxonium ions, results in an abrupt increase in the electrical conductivity, which is recorded by a conductometric detector. The hydraulic and measuring circuits of the analyzer are implemented using standard ionochromatographic equipment. It is shown than in the concentration range of the analyte 1 – 16 g/liter, the correcting additives of ammonium and potassium hydroxides do not interfere with the results of the analysis. To eliminate the interfering effect of correcting additives at low concentrations of boric acid (0.2 – 1.0 g/liter) we propose to use a Donnan dialysis through a cation exchange membrane. Optimal conditions of the analysis are specified and the metrological characteristics are determined. At a concentration of boric acid of 0.2 g/liter, the standard deviation does not exceed 2%.

Analytical method is the most important part of chemical analysis, an action guide for the analyst and carrier of information about the metrological characteristics. To confirm the parameters and legitimize the methodology, Russian specialists traditionally use the procedure of metrological certification in accordance with GOST 8.563-2009. Validation of analytical procedures or analytical methods is a concept recently accepted in Russia and causes confusion in many domestic experts. However, this internationally accepted concept is actively used for long to assure the quality of chemical analysis. The European Community for Metrology in Analytical Chemistry (Eurachem) has developed a guide to validation of analytical methods «The Fitness for Purpose of Analytical Methods»; many articles have been published on this issue. This article is devoted to generalization of the similar features and individual differences in certification, validation and verification of the methods of chemical analysis. Metrological characteristics of the analytical methods are also considered. An emphasis is made on the procedure of estimating the uncertainty as the most important stage in the development and validation of the analytical method.

The results of studying silicon single crystals and gallstones on a laboratory X-ray microtomograph with a spatial resolution of 10 µm (developed at the Federal Scientific Research Centre for «Crystallography and Photonics» of the Russian Academy of Sciences) are reviewed. The method of tomographic experiment included the use of a monochromatic «parallel beam» with subsequent three-dimensional reconstruction based on a set of two-dimensional projections. Topotomographic measurements were performed in the mode of rotation of the samples under study around the normal to the reflecting plane adjusted to the Laue diffraction reflection geometry, which made it possible to identify and study single dislocations in perfect silicon crystals. Simulation of the dislocation loops was carried out on the basis of numerical solution of the Takagi-Taupin equations. In-vitro microtomographic study of human gallstones revealed the layered structure of the gallstones which are close in composition to modifications of calcium carbonate. The internal structure of the stones is heterogeneous and contains numerous cavities and cracks formed upon their growth. At the same time, the evaluation of the porosity of gallstones is necessary, since the latter can affect the rate of stone dissolution in their treatment by litholytic methods. Linear attenuation coefficients of x-ray radiation of cholesterol-type gallstones were calculated from the measurement results. The good agreement of the experimentally obtained results and calculations based on tabular data for pure cholesterol is demonstrated which proved that the tomographic method can be used for in vivo diagnosis of cholesterol-type gallstones.

Adhesive processes are the main reason for wear of the metal-cutting tool. Adhesion-active surface structures (micro and meso-scale zones with increased density of defects having a crystal structure and high surface energy) can be identified by treating the surface with reactants by analogy with etching of a metalgraphic shlif. The level of free energy of the structural formation was estimated by the degree of darkening (dark gray color intensity) of the microstructure revealed by etching. The degree of darkening can be described and rankes quantitatively using color segmentation. Most specialized programs for metallographic image processing contain similar algorithm. The images were studied using the following indices of the structural arrangement of adhesion-active centers: the density of microstructural objects with a high value of the free energy, their relative surface area and dark gray color coefficient. A high value of the coefficient corresponds to the larger chemical potential. A comparative analysis of the character of distribution of adhesion-active zones in the surface structures of the crude and tempered P6M5 highspeed steel revealed that tempered structure contains more structural elements with high free energy (or chemical potential). Their distribution on the surface forms local zones of increased hardness, possessing high surface energy, as well as adhesion-active centers acting as potential foci for the formation of strong islet growths or zones of formation of stable adsorption films.

Principle of operation, advantages and disadvantages of the recently introduced a vibrational viscometer SV-10 are discussed. The results of measuring the viscosity of Newtonian and non-Newtonian oils on a HAAKE VT550 rotary viscometer are compared with that obtained on a vibratory viscometer in the temperature range wherein the non-Newtonian properties of oil appear and disappear. It is shown that when measuring the viscosity of Newtonian liquids, including light unstructured oils, in the temperature range where non-Newtonian properties are not manifested, the rotational and vibrational viscometers provide similar results regarding both the viscosity values and temperature dependence of the viscosity. However, when the oil temperature drops to the range of the abnormal properties, each value of the oil viscosity measured on SV-10 corresponds to the effective shear rate on the flow curve for a given temperature recorded on a rotational viscometer VT550 (the higher the viscosity, the smaller the effective shear rate). Hence, when studying the rheology of non-Newtonian structured liquids, e.g., high-paraffin oils, it is necessary to use rotational rheometers, which provide recording the entire flow curve and determining the viscosity values in transient and steady-state flow regimes. The vibration viscometer measures the viscosity of non-Newtonian structured media for some “effective” shear rate values, which are not set by the device and can be determined as a result of separate experiments with calibrated samples thus providing relative rather than absolute measurements of the viscosity. Recommendations for practical use of SV-10 vibrational viscometers are specified proceeding from the results of studying the rheological characteristics of oils obtained on both types of the viscometers.

The operating modes of loading elements of machines and structures exhibit, as a rule, more complicated character of their loading cycles compared to sinusoidal used in the practice of calculations and experiments. It is noted that in a number of cases the actual conditions of load changing can be schematized by dual-frequency loading modes with superposition of the high-frequency component of the main workload attributed to the effects of vibrations, aero- and hydrodynamic impacts, regulation of the working process, etc. Testing of three steel samples which differ in their cyclic properties has shown that such two-frequency regimes lead to a decrease in the durability in comparison with single-frequency loading, equal in the amplitude of maximum stresses. This reduction depends on the parameters of the basic low-frequency and imposed high-frequency loads. Evaluation of this reduction can be performed both i) using the laws of summation of the damage expressed in the strain terms, and ii) using an analytical expression considered below, which includes calculated or experimentally determined durability for single-frequency loading with the maximum (total) amplitude of the effective stress and durability coefficient, characteristic of each type of material and determined by the ratio of amplitudes and hours of low- and high stresses. A computational-experimental analysis of the effect of the amplitude of low-frequency and superimposed high-frequency loading under two-frequency modes of stress change on the cyclic durability showed that the imposition of the high-frequency component of cyclic deformation on the main low-cycle loading process leads to a significant decrease in the cyclic durability, the level of the decrease correlates with the level of amplitudes and frequencies ratios of the summarized harmonic processes of load application.

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

A method for separating the work of impact into two parts - the work of the crack nucleation and that of crack growth - which consists in testing two samples with the same stress concentrators and different cross-sectional dimensions at the notch site is developed. It is assumed that the work of crack nucleation is proportional to the width of the sample face on which the crack originates and the specific energy of crack formation, whereas the work of the crack growth is proportional to the length of crack development and the specific crack growth energy. In case of the sample fracture upon testing, the crack growth length is assumed equal to the sample width. Data on the work of fracture of two samples and their geometrical dimensions at the site of the notch are used to form a system of two linear equations in two unknowns, i.e., the specific energy of crack formation and specific energy of crack growth. The determined specific energy values are then used to calculate the work of crack nucleation and work of crack growth. The use of the analytical method improves the accuracy compared to graphical - extrapolative procedures. The novelty of the method consists in using one and the same form of the notch in test samples, thus providing the same conditions of the stress-strain state for crack nucleation and growth. Moreover, specimens with different cross-section dimensions are used to eliminate the scale effects. Since the specific energy of the crack nu-cleation and specific energy of the crack growth are independent of the scale factor, they are determined only by the properties of the metal. Introduction the specific energy of crack formation and growth makes possible to assign a specific physical meaning to the fracture energy.