Volume 25 № 1 2023
1. Pavel V. Gulyaev, Evgeny Yu. Shelkovnikov. Segmentation of Fragmented Reference Labels Images Using Combined Surface Curvature Detectors in Probe Microscopy. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 5-12. Download
The article relates to the field of micro and nano marking of samples. The dotted marking in the form of separate reference labels is considered. Such marking can be used to mark the product, the area under study and the lines connecting this area with macro landmarks on the surface. The cantilever of a scanning probe microscope or the indenter of a nanohardometer, the prints of which have a similar shape, were recommended as marking tools. A feature of the shape is the fragmentation of the image of the imprint, which is formed due to the swelling of the material when exposed to a cantilever or indenter. The analysis of conventional processing methods, potentially suitable for image segmentation and localization of reference marks, is carried out. The necessity of specialized localization methods solving the fragmentation problem is shown. A method is proposed where a combined surface curvature detector is used. The curvature of the surface at each point of the image raster is estimated using the radius of the contiguous circle or sphere. The curvature maxima determine the coordinates of the image segments centers (key points). The proposed method of combining is as follows. A versatile detector defines an expanded set of image key points, filtering and search parameters which are later used by a selective detector. The criterion for the localization of a reference mark is its detection by both detectors and a reduced radius of the surface curvature. To reduce the amount of key points in the image, it is proposed to use Gaussian filtering with a radius previously determined by a curvature detector. It is shown that after such processing, the differentiation of reference marks from other key points, determined by the radius of the surface curvature, increases significantly.
Keywords: reference labels, scanning probe microscope, SPM image, nanoobjects, nanomarking, curvature detector.
2. Vasily L. Vorobyov, Pavel V. Bykov, Faat Z. Gil’mutdinov, Vladimir Ya. Bayankin. Influence of VT6 Alloy Components on the Formation of Surface Layers by Ions Ar+ and N+ Alternating Irradiation. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 13-23. Download
A detailed analysis of the most informative RF spectra of the components of titanium alloy VT6 (Ti 2p, Al 2p and V 2p3/2) was carried out before and after irradiation. It is shown that the super-thin surface layer up to ~5 nm of the initial sample consists of mixed titanium, aluminum and vanadium oxides, and the deeper layers are mainly represented by atoms of the alloy components with a metallic bonding type. It is shown that under the conditions of irradiation with both N+ ions and alternately with Ar+ and N+ ions, the nitrogen accumulation and the formation of titanium nitride TiN is accompanied, especially at alternating irradiation, by the oxidation of the titanium alloy components throughout the analyzed surface layer. It is assumed that the implanted ions, bombarding the surface of the titanium alloy, transfer part of the kinetic energy to oxygen atoms from the natural oxide layer. This leads to partial atomization of the oxide film and to partial penetration of oxygen into deeper layers. Having a high chemical activity toward the alloy components, in particular, toward titanium and aluminum, oxygen atoms interact with them, forming various oxides. In addition, the irradiation is accompanied by the intensive formation of cascades of atomic collisions, their overlapping and, as a consequence, mixing of elements in the surface layers. This process is accompanied by an increase in temperature in the mixing zones and contributes to the oxidation of the alloy components and the penetration of oxygen from the residual vacuum atmosphere.
Keywords: titanium alloy, implantation of N+ ions, alternate irradiation, X-ray photoelectron spectroscopy, surface layers.
3. Artem A. Shaklein. Numerical Estimation of Singlet Delta Oxygen Effect on Polyoxymethylene Burning. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 24-37. Download
Continuously growing consumption of products results in various problems such as the necessity of the polymeric waste disposal, which creats a new worldwide field of research. Polymer incineration is one of available techniques, which major disadvantage is the pollutant and exhaust formation in the atmosphere. Plasma assisted combustion is a promising technology providing the reduction of the ignition delay time, enhancement of flame speed and stabilization of flame, which also affects the composition of combustion products and can reduce air pollution. However, a brief review shows various uncovered areas in the theory of plasma effects on flame such as unknown kinetic parameters for many reactions with excited species. In the present work a mechanism for the numerical estimation of the plasma effect on the polymer burning behavior is proposed. A reactor previously introduced for studying the incineration of polymers is employed here. The coupled formulation of a mathematical model s is proposed including heat and mass transfer between gas phase flame and solid material. The set of one-dimensional gas phase governing equations is solved using Cantera; for proper solving radiative heat transfer in optically thick medium the P1 radiation model is introduced into the source code. The one-dimensional equations of solid fuel are solved in the in-house code. Polyoxymethylene was selected as a sample of polymeric material to be incinerated. Plasma discharge is able to excite molecular oxygen from ground state (is present in the air supplied into the reactor as oxidizer) to singlet delta oxygen, O2(a1Δg). The isolated effect of O2(a1Δg) on combustion could be considered as a special case of plasma assisted combustion. Thus, the effect of plasma was modeled by partial replacement of ground state molecular oxygen (was present in air supplied into the reactor as oxidizer) by singlet delta oxygen, O2(a1Δg). Two detailed kinetic mechanisms (based on GriMech and Konnov) were chosen to resolve the O2(a1Δg) effect on formaldehyde combustion. At first, the numerical approach was tested on formaldehyde flames and methane-air flame with the addition of O2(a1Δg). The calculated results of the current study are in good agreement with the results presented in the literature. Then, the numerical study of polyoxymethylene combustion was carried out. It is shown that the replacement of 10% of O2 by O2(a1Δg) increases the maximal temperature in the reactor, polymer's mass loss rate, temperature of the burning surface, molecular and radiative heat fluxes from flame to solid material. The concentrations of some species such as O2, O2(a1Δg), H2O, CO, CH2O, OH are changed only locally in the vicinity of the burning surface, while the replacement of 10 % O2 by O2(a1Δg) has a permanent effect on the concentrations of CH4
Keywords: combustion, chemical mechanism, plasma, polyoxymethylene, numerical simulation.
4. Dmitriy K. Zhirov. The Influence of Nanodispersed Additives on the Reduction of the Coefficient of Friction of Lubricants. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 38-45. Download
The paper studies the effect of adding shungite and serpentine to oil on the friction coefficient and wear in the load range from 50 to 1500 N. Shungite and serpentine were ground in a multistage centrifugal impact mill to a size of less than 40 microns. The tests were carried out on a friction machine. Test mode: the ball moved on the plate with a frequency of 5 Hz and the amplitude of the ball movement was 3 cm at room temperature. The load was changed in steps: 50, 100, 200, 500, 1000, 1500 (N). The test time for each load was 5 minutes. The samples were balls made of steel ШХ 15 (rus.) and plates made of carbon steel 20. To hold the oil on the plate, a shoulder was made to prevent oil escaping from the friction zone and fouling the friction machine. Numerous tests were carried out with different ratios of shungite and serpentine additives. The most significant effect is observed at the shungite and serpentine concentration of 0.7 % 0.3 % (by volume), respectively. The friction coefficient decreases from 0.138 to 0.122. When the specified amount of additives is added, a stable dark coating is formed on the samples and a decrease in the friction coefficient by 13 % is observed in comparison with the base oil. The tests carried out show the effectiveness of the use of shungite and serpentine additives in oil from the standpoint of reducing the wear of the samples. The most effective will be the use of shungite and serpentine in oils with a minimum set of additives.
Keywords: shungite, serpentine, coefficient of friction, wear, friction machine, fullerene, oil.
5. Aleksandr I. Ulyanov, Alevtina A. Chulkina, Aleksandr L. Ulyanov, Vitaliy E. Porsev. Application of Mössbauer Spectroscopy to Comprehensive Investigation of Phase Composition, Phase Magnetic State of Mechanically Synthesized Fe-Mn-Ni-C Nanocomposites. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 46-56. Download
The phase composition and magnetic state of Fe-Mn-Ni-C nanocomposites (mechanochemically synthesized (MS) and subsequently annealed (Fe0.85Mn0.10Ni0.05)83C17
model alloy used as an example) were studied using X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. It is established that the as-synthesized alloy consists of an amorphous phase, cementite, insignificant amount of χ-carbide, and ferrite. During annealing at the temperature of 500 °C, the amorphous phase and χ-carbide transform into ferrite and paramagnetic cementite. The formation of austenite also starts from the annealing temperature of 500 °C. At the same time, the concentration of Mn atoms in paramagnetic cementite increases, which leads to a decrease in its Curie temperature ТC to ≈ -100 °C. At the annealing temperature above 500 °C, the alloying elements are redistributed between the phases. These peculiarities were studied using Mössbauer measurements. In particular, in the range of Tann from 500 to 700 °C a part of Mn atoms was found to segregate from the "primary" cementite, i.e. the cementite that formed as a result of MS and subsequent annealing. This caused an increase in the Curie temperature ТС of the "primary" cementite to room temperature after annealing at 700 °C. It is assumed that segregated from cementite manganese was consumed during the austenite formation. A small amount of "primary" cementite dissolved in austenite after heating the sample above 700 °C for one hour. In this case, the least stable cementite dissolved first. It can be the cementite alloyed with nickel and a small amount of manganese atoms. The subsequent cooling of the alloy leads to the segregation of "secondary" cementite from the austenite. The concentration of manganese atoms in the "secondary" cementite is significantly lower than in the remaining "primary" cementite. After annealing above 700 °C, the "primary" cementite remains in the paramagnetic state at room temperature. "Secondary" cementite is ferromagnetic at room temperature. However, its Mössbauer spectrum has a weak magnetic "splitting", which leads only to some broadening of the doublet in the spectrum of paramagnetic cementite. This fact makes it difficult to process the spectrum correctly. An adequate interpretation of the Mössbauer spectra of the alloy under study requires the additional use of magnetic methods, which can easily detect even a small amount of ferromagnetic phases in alloys.
Keywords: Fe-C-Mn-Ni carbide steels, mechanochemical synthesis, heat treatment, phase composition, magnetic susceptibility, Curie temperature, Mössbauer spectroscopy.
6. Natalya V. Izmailova, Konstantin M. Degtyarenko, Lubov G. Samsonova. Charge Mobility of Substituted Donor-Acceptor Compounds Based on Diphenylamines and Dibenzothiophene Dioxides in OLED Structures. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 57-66. Download
The charge mobility of three donor-acceptor-substituted compounds based on diphenylamines and dibenzothiophene dioxides was estimated using the transient electroluminescence method. The study was carried out for a multilayer structure containing, in addition to the emission layer (L1, L2, L3), a hole-transport layer and a hole-blocking layer: ITO/PEDOT:PSS/NPD/L/DCP/LiF/Al. A rectangular pulse with a voltage of 5–9 V and a duration of 400 μs was applied to the electrodes of the OLED structure. The electroluminescence dynamics of organic light-emitting diodes under the turn-on and turn-off of an applied voltage pulse was analyzed. The values of the times of the beginning of electroluminescence (td) reaching the intensity level of 0.5 and 0.95 when voltage was applied to the contacts of 5, 7 and 9 volts are given. To estimate the mobility of charges (holes), we used the time during which the electroluminescence intensity reached half of the maximum value. The value of charge mobility was ~10-6 cm2/(V·s). The dependence of the charges mobility on the on the square root of the applied electric field is linear and satisfies the Poole-Frenkel relation. The long afterglow of one of the compounds after removing the voltage from the electrodes is discussed under the assumption that excitons are released from triplet traps due to the effect of thermally activated delayed fluorescence.
Keywords: organic light emitting diodes, charge mobility, transient electroluminescence method.
7. Anna A. Kamilyanova, Valentin V. Kropotin, Vladimir I. Ladyanov. Modeling of the Process of the Redistribution of Impurities During the Laser Treatment of Steels. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 67-77. Download
In production, important characteristics of metal products are the distribution of impurities and the formation of micro- and macrostructure in various parts of the product. The purpose of this work is a theoretical description and modeling of the laser action process on a steel plate, which allows describing temperature and concentration fields on the macroscopic scales of the entire product. The model equations include the energy conservation, diffusion, impurity balance equations and kinetic crystallization and melting equations. The model is quasi-equilibrium and is conceptionally close to the two-phase zone approach. According to the obtained dependencies, it is possible to analyze the process of heating, melting, and crystallization in the sample material. The studies were carried out at a stationary position of the laser radiation source. We obtained certain regularities of the process by varying different parameters of the model. The studies on the standard types of laser processing such as metalworking by laser welding and electron beam welding can be used for the explaination of the type of the dependencies obtained. The obtained curves show a strong relationship between the parameters of laser radiation and the system characteristics. It is possible to clearly observe the processes of phase transformations and determine the approximate penetration depth of the material. This model can be expanded to include a multiphase description for multicomponent system. The results obtained in this work will be helpful in further studying the problems of alloying of the steel products surfaces with powder mixtures.
Keywords: mathematical modeling, heat and mass transfer, structure, laser technologies.
8. Maksim S. Konovalov, Vladimir I. Lad’yanov, Marina I. Mokrushina, Pavel G. Ovcharenko. Effect of Carbon on Wear Resistance, Strength and Hardness of a Composite with a Matrix of the Fe-Cr-Mn-Mo-N-C System. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 78-87. Download
Composite ingots with a Fe-Cr-Mn-Mo-N-C system matrix and reinforcing particles in the form of conglomerates of MgO, Al2O3, AlN were produced by aluminothermy that is one of the versions of self-propagating high-temperature synthesis. The resulting ingots differed mainly in the content of C. It has been established that an increase in the carbon content in the composite from 0.01 to 0.50 wt. % leads to an increase in hardness from 238 to 271 HV and wear resistance. The latter property was evaluated when testing materials for abrasive wear under conditions of dry friction of samples on the surface of a fixed abrasive - electrocorundum skin with abrasive particle sizes of P400 (28 – 40 µm) and P80 (200 – 250 µm). As a criterion of wear resistance, a decrease in the mass of the sample after testing was taken. The pressing force of the tested material to the surface of the abrasive was ~ 0.25 N/mm2, the time of one test was 90 seconds. The weight loss of the samples was measured using a VLR-200 balance. The hardness was measured by the Vickers method using an ITV-1-A hardness tester in accordance with GOST 2999-75 with a holding time of 10 seconds at a load of 30 kgf. It has been established that with an increase in the carbon content in the composite, its embrittlement occurs. In this case, samples with 0.01 and 0.16 wt. % C during the compres000sive strength test do not collapse, and at 0.50 wt. % C, cracks appear, and the samples continue to deform without complete destruction up to the maximum allowable load for the testing machine. The evaluation of the compressive strength according to the load at which cracks appear shows that it is equal to 3210 MPa. Tests to determine the ultimate compressive strength were carried out on a universal testing machine REM-100-A-2.
Keywords: composite, alloy, wear resistance, strength, hardness of composite, ultimate compressive strength.
9. Fatima A. Mustafayeva, Najaf T. Kakhramanov, Ismayil A. Ismayilov. Physical-Mechanical and Thermal Properties of Titanium Dioxide-Modified Composites Based on Aluminum Hydroxide and Polyethylene Mixture. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 88-95. Download
The results of the study of the physical-mechanical and thermal properties of composites modified with a structure-forming agent based on aluminum hydroxide and a mixture of high and low density polyethylene are presented. The properties of polymer composites such as ultimate tensile strength, elongation at break, melt flow index, Vicat softening temperature, thermal stability and thermomechanics were studied. All composite materials were based on a 50/50 mixture of high and low density polyethylene modified with titanium dioxide (1 wt %). The amount of aluminum hydroxide varied within 1-30 wt %. On the basis of the data obtained on the Kanavets device, curves of the temperature-dependent deformation were constructed and the regularities of the changes in thermomechanical curves were established. It is shown that for all the studied samples, with increasing temperature, a transition from the solid to the viscous-flow state is observed. Thermal stability was evaluated according to thermogravimetric analysis.
Keywords: low density polyethylene, high density polyethylene, polymer blend, structure-forming agent, titanium dioxide, aluminum hydroxide, flame retardant.
10. Nikolay A. Proshutin, Petr N. Krylov, Raushaniya M. Zakirova. Ion-Plasma Nitriding of Aluminum. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 96-104. Download
The experimental study of ion-plasma nitriding of aluminum was carried out on an upgraded UVN71-P3 unit. The aim of the present work is to select the optimal mode of ion-plasma nitriding of aluminum. Aluminum alloy was used as modified material. The elemental composition of the initial aluminum alloy was determined by energy dispersive microanalysis. To achieve the goal, the following tasks were solved: to prepare aluminum samples (before nitriding); to nitride the surface layer of samples on the experimental UVN71-P3 unit; to study the structure and phase composition of the surface layer; to perform mechanical (to determine microhardness) tests of modified samples; to determine the optimum mode of the aluminum samples modification. Nitriding was carried out in 5 regimes; nitriding time was constant; voltage displacement frequency was changed. The microstructure of the material was studied by optical microscopy using a MII-4 microscope. The analysis of the phase composition, lattice period values and average sizes of the areas of coherent scattering of the surface layer were performed by X-ray diffraction on a diffractometer DRON-3. The mechanical tests such as the microhardness determination of the modified surface were carried out by the Vickers method on a PMT-3 device. During the test on microhardness a load of 0.098 N (10 g) was applied, the average of ten measurements was defined. The microhardness of an aluminum sample before nitriding was 40 kg/mm2; the sample nitrided at constant displacement had the microhardness value of 88 kg/mm2; the microhardness of samples nitrided at pulse displacement voltage practically did not change compared to original (not nitrided) aluminum. The lattice parameters of the samples were determined by the extrapolation method. The dimensions of coherent scattering regions for diffraction reflection from the plane (111) were estimated using the Selyakov-Scherrer formula. The size of the DCD depends on the displacement frequency; it increases for the samples nitrided at 15, 20, and 27 Hz and decreases at 5 and 30 Hz. The lattice parameter a in all the nitrided samples is increased compared to the initial one. The presence of a modified layer on the surface of the nitrided samples is observed. The effect of the bias voltage regime on the nitriding of aluminum is revealed. The X-ray phase analysis shows no presence of aluminum nitride. The microhardness of aluminum increases when the nitriding mode at constant bias voltage is used.
Keywords: nitriding, aluminum nitride, independent glow discharge with hollow cathode, pulse bias voltage, DC bias voltage, X-ray phase analysis, microhardness.
11. Natalia V. Filatova, Nadezhda F. Kosenko, Mikhail A. Badanov. Influence of Heat Treatment and Mechanoactivation of Kaolinite on the Process of Mullite Formation. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 105-112. Download
Mullite is the most important product obtained from natural silicate raw materials, primarily kaolins. We used enriched kaolin of the Sukhoi Log deposit; the content of impurities (TiO2, Na2O, MgO, K2O, Fe2O3) did not exceed 1.5 %. Losses during calcination and the content of free quartz were 13.8 % and 4.4 %, respectively. The Hinckley index, which characterizes the degree the structural order, was equal to 1.76, which indicated a low degree of defectiveness of kaolin. The mullite formation is influenced by various factors, for example, heat treatment mode and pre-machining. The effect of the heating rate of kaolinite Al4[Si4O10](OH)8 on its transformation into mullite 3Al2O3·2SiO2 was studied. As the heating rate was increased, the mullite yield increased. The high rate of the temperature rise contributed to the rapid dehydration of kaoliniteaccompanied by the detachment of hydroxide groups and the disordering of the structure, especially at low temperatures. The influence of the mechanical pretreatment of kaolin in a ball-and-ring mill (providing an abrasive effect on material) was compared with the influence of the mechanical pretreatment in a planetary mill, in which impact loads predominate. The abrasive effects on layered structures which can split during treatment are of interest. It is established that mechanical attrition treatment leads to the sliding of individual packets (or their aggregates) of layered silicate relative to each other, while hydroxogroups remain "sealed" inside the packets. The abrasive treatment of kaolinite in the ball-and-ring mill contributes to a slight shift in the maximum of the dehydroxylation process (by 6 °C) and does not contribute to an increase in the yield of the product (mullite). Intensive impact-abrasion treatment in a planetary mill breaks up packets and layers; a part of hydroxogroups appear on the outer surface of polycrystallites, which facilitates the dehydroxylation process. The number of defects in the solid phase increases dramatically, and mechanical destruction cannot be eliminated ("healed") with slow firing. As a result, the thermal effect generated by the detachment of hydroxogroups shifts to temperatures which are lower by 18 °C; and the effect area reduces by 46 %; the Hinckley index decreases to 1.63. The increase of the mullite content - is almost 100 % of theoretically possible.
Keywords: kaolinite, kaolin, heat treatment mode, mechanoactivation, abrasion, impact treatment, mullite formation.
12. Elina F. Khametova, Olga R. Bakieva. Development of a Software Package for Quantitative Analysis of Chemical Composition by Auger-electron Spectra. Chemical Physics and Mesoscopy, 2023, vol. 25, no. 1, pp. 113-119. Download
Currently, reverse engineering is actively used in the field of microelectronics. Layer-by-layer methods are usually used to detect manufacturing defects and restore the architecture of microcircuits. One of the methods is Auger electron spectroscopy (AES) with layer-by-layer ion etching. It is known that each atom has its own electronic structure and, accordingly, its own Auger transition energy; this is a characteristic value by which the sort of an atom is determined. Thus, it is possible to draw a conclusion about the chemical composition of the surface. The present work is devoted to the development of a program for the processing and analysis of experimental Auger electron spectra. In the course of the work, some problems were identified both in determining the presence of a signal (identification of a weak signal) and belonging of the signal to a specific chemical element. To date, the developed program is capable of performing a qualitative and quantitative analysis of experimental data in a semi-automatic mode. The program input data are in the form of a two-column text file that contains the conditions and output data of the experiment. The output data of the developed program are the information about the chemical composition of the surface and the concentration of identified chemical elements displayed on the screen. The work of the program was certified based on the experimental data obtained for different contents of chemical elements. Using the program, both the chemical composition of each test object and the concentration of all identified chemical elements were correctly determined.
Keywords: software, Auger electron spectroscopy, data processing and analysis, Python.