An important chemical impurity in the composition of zirconium materials for nuclear power engineering is hafnium, the content of which should not exceed 0.05 and 0.01% for domestic and foreign alloy grades, respectively. Hafnium, being an analogue of zirconium in its chemical properties, is difficult to be analyzed using classical methods of analytical chemistry. Among the physical methods, the X-ray fluorescence method is the most expressive, which is important in conditions of continuous production. The method of X-ray fluorescence for measuring the content of hafnium in zirconium-containing material has been tested on the example of potassium fluorozirconate, a precursor for obtaining alloys. With various combinations of crystal analyzers, detectors, and collimators of the wave-dispersive spectrometer, the ratios of the intensities of the analytical lines of Hf and Zr in the second order of reflection were refined, and the degree of decrease in the fluorescence intensity of those lines was determined. The X-ray fluorescence spectra of hafnium lines in potassium fluorozirconate at the content characteristic of nuclear-pure zirconium are studied. The possibility of recording the intensity of the Hf analytical lines and methods of eliminating the interference from the Zr lines in the second order of reflection are considered. The metrological characteristics are calculated for Hf analytical lines. It is shown that the smallest error and the lowest detection limit (0.001%) is provided when using the HfLβ1 line at certain settings of the wave-dispersive spectrometer, including the X-ray tube operation mode, a combination of a crystal analyzer, a detector and a collimator, as well as the amplitude discriminator settings. The method of accounting for the background is recommended. The proposed method of hafnium determination is applicable to the materials with a constant content of zirconium.

A routine linear and 2D scanning procedure using the inductively coupled plasma mass spectrometry with laser ablation (LA-ICP-MS) is often used when studying the composition of zonal and polyphase solid objects (crystals, rocks, alloys, etc.). However, the proper interpretation of the data necessitates taking into account the features inherent to the procedure. One of the most important features of the results obtained for the objects contrasting in composition is the asymmetry of the concentration profile of elements when going from high to low and, to a lesser extent, when going from low to high contents. Physical processes accompanying the analysis of rocks with the aforementioned features are considered. The duration of the time of signal distortion upon change of one crystal phase to another at large differences in the content of elements is estimated. To obtain the correct data for linear and 2D scanning using LA-ICP-MS, the scanning should be performed point by point: to avoid the influence of crater effects, points should be spaced 1.5 – 2.0 laser beam diameter apart. The goal of obtaining of reliable results requires also keeping the time intervals between measurements of at least 2 – 5 sec.

A procedure for determination of the residual content of N,N-dimethyl-1,3-propanediamine (DMAPA) during synthesis of N,N-dimethylaminopropylamides of fatty acids (DMAPA FA) from coconut oil has been developed. The analysis was performed using high performance liquid chromatography on a Shimadzu LC-20 Prominence device equipped with a diode array detector and reversed phase column GL Sciences Inertsil ODS-3. Precolumn derivatization was carried out with a 13% — dansyl chloride (5-(dimethylamino)naphthalene-1-sulfonyl chloride) solution in acetone to increase the analyte response. The selected composition of the mobile phase — acetonitrile and triethylamine phosphate buffer solution (pH 3.0) in a volume ratio of 2:3 and optimized chromatographic conditions provided a clear peak of DMAPA with a retention time of 8.7 – 8.9 min. The proposed method provides determination of 0.02 – 10% DMAPA in DMAPAFA samples. Correctness of the procedure was confirmed in spike tests. The results obtained can be used for assessing the degree of conversion of starting materials in the synthesis of N,N-dimethylaminopropylamides of fatty acids, as well as for forecasting the content of N,N-dimethyl-1,3-propanediamine in the products on their base.

Beryllium products exhibiting a low level of absorption of the radiation energy are widely used in scientific instrumentation design (x-ray technology, radiation detectors, etc.). We present the results of studying the leak tightness of products (disks, plates) made of technical sintered beryllium of standard purity and foil obtained by «warm» rolling from high-purity beryllium. The relevant standards and requirements for testing are given. The leak tightness control was performed using mass spectrometric helium leak detectors with forevacuum backing pumps (oil and dry diaphragm pumps) and specialized vacuum equipment. The parameters of tightness of samples made of technical sintered beryllium were determined. The level of the helium signal during blowing was (0.6 – 7.4) × 10^–11 Pa · m³/sec, which corresponds to the tightness standard of foreign analogues and matches the requirements of domestic manufacturers of x-ray equipment. The data spread tended to increase due to the growth of the background value. The obtained results can be used to improve high-tech equipment intended for flaw detection, medical devices, rapid analysis of ore raw materials, radiation safety equipment, etc.

Hardening of mineral binders (cement, gypsum, lime, clay) is accompanied by the dissolution of minerals from the binder surface, their chemical interaction with water (the reaction of hydration and hydrolysis), and the formation of a solution saturated with respect to new hydrates. The reactions of minerals with water continue for some time even after saturation when water molecules are adsorbed by the solid phase of the binder. An «intermediate» colloidal system thus formed is characterized by the viscosity or plasticity depending on the water content in it. At the final stage, the processes of recrystallization and coalescence of the particles in a colloidal solution occur resulting in solidification and hardening of the solution and increased strength of the formed stone. We present the results of studying the hardening kinetics of the aqueous solution of a mineral binder using electrical and optical methods with high time resolution. Semi-aqueous gypsum was selected as a mineral binder. During hardening, the resistance and the capacitance of the samples were measured along with the visualization of the spatial structure of the solution. The mineral composition of water significantly affected the character of hardening. Noticeable fluctuations of the electrical parameters were detected in the experiments with mineral water. Optical measurements showed that solidifying solution is similar in structure to dendrites and fractal dimensionality of the structure almost remains the same during growth. It is also shown that at the initial stage the hardening proceeds by the logistics law. The results obtained can be used and recommended for practical application for determination of the kinetic parameters of hardening and in diagnostics of the structure of materials based on mineral binders.

Most of the technological processes of coal mining and primary processing (transportation, crushing, and enrichment) depend on the physical and chemical properties of the external surface of coal particles. When determining the wetting angle — the wettability characteristics of the coal surface — the method of preparing the working surface of the sample and the choice of the measurement procedure (a drop of liquid on a solid surface or fixing a gas bubble on the surface of coal placed in water) are of great importance. We present the results of determining the contact angle of wetting using an air bubble. The working surface was prepared by briquetting a powdered sample. Scanning electron microscopy and laser diffraction analysis of the particle size distribution were used for surface characterization and fractional analysis of carbon particles. It is shown that the contact angle of wetting depends on the particle size, mineral composition of coal, and pressing pressure. At the same time, when determining the wetting angle, the optimal particle size and pressing pressure of the briquette are <100 μm and ~500 MPa, respectively. The obtained results can be used to improve technologies for mining, conversion and dressing of coals.

The kinetics of fatigue crack growth has been studied in tensile testing of compact steel tensile specimens (S(T)-type) in the middle section of the kinetic diagram of fatigue fracture (fatigue crack growth diagram) under regular and irregular loading with different asymmetry and maximum load values. The samples were tested on a BISS Nano-25kN servo-hydraulic machine. Standard loading spectra typical for different technical objects exposed to alternating loading during operation were used. The values of the crack growth rate per cycle in the loading block were obtained. Parameters for assessing the character of irregular loading and crack closure, namely, the irregularity factor and crack closure coefficient were proposed. When calculating the effective value of the range of the stress intensity factor (SIF) at the crack mouth, we propose also to take into account the loading irregularity in addition to the closure coefficient. With this approach, the obtained fatigue crack growth diagrams can be grouped into one equivalent curve, which is characteristic of regular loading with R = 0. Moreover, grouping of the fatigue crack growth diagrams provided the use of unified parameters when calculating the crack growth kinetics, regardless of the type and parameters of loading, which rather simplified the crack growth determination. The fatigue crack growth life was predicted taking into account the crack «closure» and the nature of loading according both to the approach developed by the authors and by cyclic calculation method (cycle-by-cycle). All the data obtained are tabulated and classed according to the type of loading. The calculation results and experimental data showed good convergence, which was confirmed by the high values of the correlation coefficient.

The results of a comprehensive computational and experimental study of the kinetics of low-cycle fatigue cracks (LCF) in a turbine disk made of EP741NP granular nickel alloy of an aircraft gas turbine engine under complex loading cycles (CLC) are presented. The configuration of crack fronts was reconstructed using light microscopy. Steps of the blocks of fatigue striations characterizing the crack increment under CLC at the stage of steady crack growth are measured using scanning electron microscopy during microfractographic analysis. The period of LCF crack steady growth is estimated and the reproducibility of the regularities of steady growth is demonstrated which testifies the capability of reliable prediction for LCF crack steady growth. The finite element modeling of the reconstructed crack fronts has been carried out. The values?? of the range of stress intensity factor at each crack front in the area of measuring the pitch of the striation blocks were calculated for the subcycles of complex loading cycles. Using the previously developed physically grounded mathematical model and calculation methodology, forecasting of stable growth of the LCF crack was carried out. The results of forecasting match the data of micro-fractographic analysis unlike the results of LCF crack growth prediction based on Paris law which differ significantly from experimental data.

The results of studying fracture of a batch of fiber-reinforced polymer (FRP) specimens upon compression are considered. The kinetics of damage and fracture of structural bonds in the FRP package under the impact of compressive load has been studied using acoustic emission (AE) in combination with video recording. Correlations between fractures occurring on the micro-, meso-, and macroscopic levels of the FRP package and the AE events registered at the same time, i.e., their energy parameters, shape, and spectrum were determined. New criterion parameters including the activity of registration of AE events in energy clusters and their weight content were analyzed. The structural-phenomenological approach, implemented by dividing the entire array of acoustic emission data into energy clusters provided the possibility of control of the kinetics of the material fracture using the registration activity and the weight content of AE events in clusters of the lower, middle and upper energy levels. Comparison of the AE events recorded at the stages of loading of the tested specimens with video footage of the fracture of structural bonds in the FRP package made it possible to set up a correspondence between the occurring damage and the recorded AE signals, their parameters, shape and spectrum.

Heat-resistant alloys (superalloys) widely used for manufacturing parts of various components of aircraft engines are complex nickel-based systems which contain apart from alloying (Al, Cr, Co, Ti, Mo, W, etc.) and microalloying additives (B, Mg, REM, etc.) different amounts of the impurities (Mn, Fe, Si, Pb, As, Sn), including gas-forming (O, N, C, S) ones. The use of additive technologies (AT) in manufacturing of complex-shaped parts made of these alloys makes it possible to increase the material utilization coefficient and shorten the technological process. However, the use of AT requires real-time control of the composition of semi-products and finished products at all stages of production. Study of various stages of manufacturing parts from ZhS6K and VZh159 alloys using an AT of selective laser alloying (SLA) is carried out using analytical control systems of the laboratory of the Testing Center (TC) of FSUE «VIAM». A complex of methods for atomic emission, mass spectrometric and X-ray fluorescence determination of different groups of elements was used for the analysis of charge materials, cast bar blanks, metal-powder compositions (MPC) and synthesized parts. The results of analysis of nickel N-1u and chromium Kh99N1 used upon and after smelting of cast billets, as well as analysis of MPC of these alloys carried out by different methods are presented (gas analyzers were used to determine the gas-forming impurities). Monitoring on the chemical composition of materials throughout the process of additive manufacturing ensure their compliance with the regulatory requirements and predict the properties of finished products. The work was carried out within the framework of complex scientific direction 2.1 «Fundamental research» («Strategic directions for the development of materials and technologies for their processing for the period up to 2030»).