Phase Analysis Method Research Articles

Особливості взаємодії лігатури Fe-Ni-Cr-Cu-Mn з сірим чавуном

The use of antifriction cast irons operating under lubrication conditions for manufacturing machine and mechanism parts is currently inefficient and unjustified due to the need for continuous lubrication. This complicates maintenance, increases the risk of environmental contamination by lubricants, and also results in relatively low strength and resistance to impact loads. This work investigates the possibility of creating an antifriction material with self-lubricating capabilities during operation by alloying gray cast iron with the Fe-Ni-Cr-Cu-Mn alloy system. The process of obtaining the alloy is explored with the aim of developing technological conditions for producing a high-entropy alloy by casting. The research was conducted using metallographic, X-ray phase, and chemical analysis methods. Technological modes for the production of the Fe-Ni-Cr-Cu-Mn alloy have been developed. It consists of two solid solutions with FCC lattices and complex carbides (FeCr)7C3. It was shown that its liquidus and solidus temperatures (1346 °C and 1004 °C, respectively) are relatively low, which makes it suitable for alloying gray cast iron. This allows avoiding significant overheating and holding during alloying, thereby improving the energy efficiency of the process. It was established that the optimal amount of alloy addition to gray cast iron is 0.5% by weight, and the resulting alloyed material, in terms of its chemical composition, structure, and properties, is closest to standardized antifriction cast irons. The use of the Fe-Ni-Cr-Cu-Mn alloy provides an opportunity to develop an energy-efficient technological process for producing an antifriction material capable of self-lubricating during friction.

Sol-gel synthesis, structure and magnetic properties of barium aluminoferrite for use in magnetorheological fluids

A promising area of application of micro- and nanosized magnetic particles is the creation of magnetorheological materials in which such particles are a component of a complex dispersed phase. Of greatest importance is the high shear stress in suspensions based on magnetic particles when a magnetic field is applied, as well as low value of the coercive force. The aim of the work was to study the structure, morphology, and magnetic properties of barium aluminoferrite powders, and to evaluate their effectiveness in magnetic fields by the rheological properties of magnetorheological fluids fabricated using them. Barium aluminoferrite BaAl2Fe10O19 of hexagonal structure was synthesized by the citrate sol-gel method. Using the methods of X-ray phase analysis, scanning electron microscopy, IR spectroscopy, magnetometry, its structural and microstructural features, and magnetic properties were studied. The powder had a maximum specific magnetization M = 20.4 A × m2/kg and a coercive force Hc = 4.8 kOe (at 300 K). The high shear stress (3.5 kPa) at a relatively low magnetic field induction (625 mT) makes it possible to consider the resulting material as promising for use as an additional functional filler for magnetorheological fluids.

Toward higher-frequency fringe projection profilometry with fewer patterns.

Phase unwrapping is crucial in fringe projection profilometry (FPP) 3D measurement. However, achieving efficient and robust phase unwrapping remains a challenge, particularly when dealing with high-frequency fringes to achieve high accuracy. Existing methods rely on heavy fringe projections, inevitably sacrificing measurement efficiency. To address this problem, we propose a novel, to the best of our knowledge, phase analysis method based on composite fringe patterns. By embedding a multi-period space-varying phase shift (SPS) into the phase domain, the noise amplification issues in high-frequency phase unwrapping is effectively addressed. Our proposed method requires fewer patterns than conventional methods, utilizing only four fringe patterns for absolute phase retrieval. Experimental results confirm the feasibility of our proposed method and demonstrate its superior efficiency and accuracy through quantitative comparisons.

LOW-TEMPERATURE SYNTHESIS OF FINE-POROUS CORUNDUM BASED ON INCORPORATED GRAPHENE NANOSTRUCTURES

In the present paper, the effect of the addition of graphene nanostructures and 3 mass % TiO2 on the microstructure and properties of sintered corundum ceramics were studied. Fine-porous corundum ceramics were obtained by the method of solid-phase sintering at relatively low temperatures of 1450oC, by adding graphene nanostructures in an amount of 2 % or 20 %. To lower the synthesis temperature, 3 mass % TiO2 was added to the initial ceramic blends. As a result of the solid solution formed between Al2O3 and TiO2, a well-sintered corundum ceramic is obtained at synthesis temperature lower than that of pure corundum - 1450oС. For the characterization of the initial blends and the ceramic samples, the methods of X-ray phase analysis, infrared spectroscopy, SEM, TEM EDS and visual microscopy were used. Besides, the basic physicochemical properties of the samples synthesized based on corundum were determined, e.g. water absorption (WA, %), apparent density (AD, %) and apparent (open) porosity (Pa, %).

SEGREGATED ELECTRICALLY CONDUCTIVE NANOCOMPOSITES BASED ON THERMOPLASTIC ELASTOMERS AND GRAPHITE

The paper presents the results of a study of the electrical conductive characteristics and a complex of physical-mechanical properties of graphite-based nanocomposites, a wide range of polyolefins - low-density polyethylene, high-density polyethylene, isotactic polypropylene, random copolymer of polypropylene, block copolymer of propylene with ethylene, ethylene/hexene copolymer and ethylene/butene-1 copolymer. For the considered nanocomposites based on polyolefins, the optimal concentrations of graphite were determined, at which the maximum values of electrical conductivity are achieved, within the range of 10–2–10–3 (Ωm)–1. A detailed description of the mechanism of tunneling and electronic electrical conductivity in the nanocomposites under consideration is given. Thermoplastic elastomers (TPE) based on polyolefins and ethylene-propylene-diene rubber have been developed. In a wide concentration range, the regularities of changes in the electrical conductivity of nanocomposites based on thermoplastic elastomers and nanodispersed graphite have been determined. When studying the physical-mechanical properties of TPE nanocomposites, the tensile strength, yield strength, elongation at break, bending strength, Vicat softening temperature, melt flow rate, and Young's modulus were determined. The regularity of the change in the dependence "stress-strain" for TPE depending on the content of ethylene-propylene-diene rubber has been established. Using the methods of derivatography, X-ray phase and SEM analyses, and electron microscopy, studies were carried out to assess the structural features of nanocomposites of thermoplastic elastomers depending on the ratio of the mixture components used. For visual interpretation, a schematic representation of the processes occurring in the interfacial region of thermoplastic elastomers is given. The method of X-ray phase analysis shows the regularity of the change in the degree of crystallinity of thermoplastic elastomers depending on the content of rubber and graphite. The principal possibility of obtaining flexible electrically conductive materials with predetermined properties by controlling the ratio of components in the composition of thermoplastic elastomers is shown. For citation: Kakhramanov N.T., Allahverdiyeva Kh.V., Gahramanli Yu.N., Mustafayeva F.A., Sadikhov N.M., Martynova G.S., Valimatova N.I., Gurbanova R.V. Segregated electrically conductive nanocomposites based on thermoplastic elastomers and graphite. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 122-137. DOI: 10.6060/ivkkt.20246711.7045.

Structure and Properties of the Electroexplosive Coating of the TiB2-Ag System after Electron Beam Treatment

A coating of the TiB2-Ag system was formed through the use of sequential operations of electroexplosive spraying and electron beam processing. The values of electrical conductivity (62.0 MS/m), Vickers microhardness (0.251-0.265 GPa at the point of measurement on a silver matrix and 25-32 GPa at the point of measurement at inclusions of boride phases), nanohardness (4.48 ± 0.76 GPa) were determined), Young’s modulus (116±29 GPa), wear parameter under dry friction-sliding conditions (1.2 mm3/N • m) and friction coefficient (0.5). Switching wear resistance during accelerated tests was 7000 on and off cycles with an electrical resistance of 10.01 - 11.76 LiOhm. The thickness of the coatings is 100 microns. The coatings are formed by a silver matrix with inclusions of titanium borides located in it with three types of sizes: nanocrystalline, submicrocrystalline and microcrystalline. Quantitatively, in the structural composition among titanium borides, titanium diboride and silver (56 wt. %) are formed predominantly (41 wt. %), while other titanium borides account for 3 wt. %. Structural transformations are described using complementary methods of X-ray phase analysis, scanning and transmission electron microscopy.

SYNTHESIS AND PHYSICO-CHEMICAL PROPERTIES OF A NEW COMPLEX FERRITE

The article discusses the synthesis of new complex ferrite, radiographic and electron microscopic studies. The phase of complex ferrites was synthesized by the method of high-temperature sol-gel synthesis. For the first time, the structure of CrKFe2O5 Composite ferrite was studied by X-ray phase analysis and scanning electron microscope methods, the syngony type, elementary cell parameters, radiographic and pycnometric densities, and elemental analysis were determined. A comparative analysis of the relationship between the parameters of the Crystal cell of primary substances and the parameters of the obtained complex ferrite Crystal cell was carried out. Micro-samples were taken from different parts of the crystallite obtained through a scanning electron microscope, the elemental composition of the crystals was analyzed, and the general type of layer of the complex ferrite surface was demonstrated. As a result, the fact that the compound consists of two phases, the clarity of its construction was determined by the topography and chemical composition of the compound. As a result, it was found that the newly synthesized complex ferrite corresponds to the Formula CrKFe2O5. The particle size of the compounds formed is large (between 200 μm, 20.0 μm, 5.00 μm and 2.00 μm).

Qualities of Regenerated Mixtures of Adsorbents

A proposal has been presented for the regeneration of a spent sorbent mixture, comprising activated carbon (BAU-A brand) and kieselguhr (Bekogur 200 brand), in a mass ratio of 1:3. The effectiveness of the regeneration process and the potential applications of the spent sorbents were determined through X-ray phase analysis methods. The study included an investigation into the adsorption of the primary dye (methylene blue) by activated carbon and various sorbent mixtures. The observed efficiency of regeneration supports the recommendation of using a combination of kieselguhr and activated carbon sorbents for treating wastewater in food industry enterprises.

METHOD FOR OBTAINING NANOPARTICLES OF IRON-CONTAINING OXIDES AND STUDYING THEIR PROPERTIES

The synthesis of iron-containing oxide nanoparticles is of interest in medicine, electronics and ecology due to their unique physical and chemical properties, such as magnetic, catalytic and adsorption properties, which allow their use in various technological processes. In this regard, this article presents the results of obtaining nanoparticles of iron-containing oxides and studying their physical and chemical properties. It is known that stabilization with natural polymers is of great importance in the production of metal nanoparticles. Therefore, in this work, the synthesis is carried out at high temperature by stabilization with potassium humate. To study the properties of the resulting iron-containing nanoparticles, methods of X-ray phase analysis, transmission electron microscopy and infrared spectroscopy were used. As a result of physicochemical studies, the heterogeneity and monodispersity of the synthesized metal nanoparticles was established. The average particle size of the synthesized samples was 8.3 nm, the crystal lattice parameter was 0.8426 nm. The result of the study using IR spectroscopy confirms the assumption of oxidation of the samples. In addition, it was found that the prepared samples have a high degree of crystallization. Transmission electron microscopy revealed no differences in the sizes of nanoparticles. Pure iron oxide is not formed during the synthesis of iron nanoparticles using the method used in the research work. The unique properties of iron-containing oxide nanoparticles obtained as a result of research are promising for the creation of innovative technologies and solutions aimed at improving the quality of life and sustainable development of society.

Новый катодный материал La2/3Cu3Ti4−xFex O12−δ для твердооксидного топливного элемента: синтез и электропроводность

Copper lanthanum titanate La2/3Cu3Ti4−xFexO12−δ x = 0–1 was doped with Fe3+ cations. The diagram of the dependence of the tolerance factor on the relative electronegativity of cations for all studied compositions was represented. It was shown that all the compositions exist in the region of existence of distorted perovskite. X-ray diffraction and X-ray phase analysis methods established the region of existence of solid solutions of La2/3Cu3Ti4−xFexO12−δ obtained by ceramic technology, which was 0 ⩽ x ⩽ 0.4. The temperature dependences of electrical conductivity for the compositions from the region of existence of solid solutions La2/3Cu3Ti4−xFexO12−δ were obtained. The ionic-electronic nature of conductivity was suggested. It was shown that the decrease of electronic conductivity under the increase of iron content was due to the compensation of electronic carriers formed during acceptor doping.

Влияние технологических параметров на микроструктуру и свойства сплава AlSiMg, полученного методом селективного лазерного плавления

Introduction. The development of additive technologies is aimed at the synthesis of new powder compositions for selective laser melting plants, the study of the effect of mode parameters on the stable quality of products. The purpose of this work is to study the effect of the scanning strategy on the microstructure, elemental composition, porosity and density of specimens obtained by selective laser melting from non-spherical powders (Al — 91 wt. %, Si — 8 wt. %, Mg — 1 wt. %), subjected to special preparation to determine the optimal conditions for selective laser melting. The research methods are methods of X-ray diffraction and X-ray phase analysis, transmission electron microscopy. The paper examines specimens formed using four different scanning strategies. Results and discussions. A promising aluminum alloy AlSi8Mg is developed for selective laser melting. The material has good manufacturability and low powder cost. The technological parameters of melting make it possible to form a thin structure with a low level of porosity. The mechanism of influence of the scanning strategy on porosity, surface morphology, relative density and microstructure is investigated. A specimen from the AlSi8Mg powder composition with a high relative density of 99.97 % is produced by selective laser melting with an energy density of 200 J/mm3, a specimen scanning circuit when the direction of laser movement changes by an angle of 90° each odd layer. It is proved that the density of the AlSiMg alloy depends on the scanning strategy used. The calculated density of the specimen was 2.5 g/cm3, which corresponds to the density of silumin. Analysis of SEM images and maps of the distribution of elements (Al, Mg, Si) of the specimens showed that different specimen formation strategies do not affect the nature of silicon distribution. A unique grain structure is observed in the resulting AlSi8Mg alloy. The melt pool consists of small grains along the border and large grains in the center. The formation of fine grains is explained by the addition of Si and the high cooling rate during selective laser melting.

Study of the Structure and Properties of Magnetic Nanopowders of Magnetite-Maggemite Series Solid Solutions by SAPNS

Nanopowders of the magnetite-maggemite series were synthesized by both aqueous precipitation and using sol-gel technology. A comprehensive comparative study of the structure of the synthesized powders was carried out using the methods of X-ray phase analysis (XPA), scanning electron microscopy (SEM), low-temperature nitrogen adsorption and small-angle polarized neutron scattering (SAPNS). It has been established that the synthesized iron oxide nanopowders are porous systems that, depending on the synthesis method, have a one-level or two-level (for powders obtained by aqueous synthesis) and three-level (for powders obtained by the sol-gel method) hierarchical structure organization with different characteristic scales and types of aggregation for each from structural levels, and the characteristic size for the larger level in both cases exceeds 45 nm. It was revealed that the magnetic structure of the obtained iron oxide powders, regardless of the synthesis method, consists of superparamagnetic particles with a characteristic magnetic radius RМ ≈ 4 nm and magnetic-nuclear cross-correlations RMN ≈ 3 nm for powders obtained by the sol-gel method; and with RM ≈ 5–11 nm and RMN ≈ 4–8 nm for powders obtained by aqueous synthesis, depending on the production conditions.

Influence of plasma synthesis parameters on the magnetic, structural and photocatalytic properties of copper ferrite

CuFe2O4 cubic copper ferrite nanoparticles were synthesized by a new plasma method, the advantage of which is the short duration of processing and cost-effectiveness. To select optimal synthesis conditions, central compositional rotatable experimental planning was used. Using the methods of X-ray phase analysis, vibration magnetometry, electron microscopy, and UV spectroscopy, the sizes of crystallites, the intensity of peaks in X-ray diffraction patterns, dislocation density, saturation magnetization, coercive force, and the degree of degradation of 4-nitrophenol were determined. To study the effect of pH on the composition of the resulting copper ferrites, cyclic voltammetry was used. The kinetics of the ferritization process under the influence of a plasma discharge has also been studied. A mechanism for ferritization in the Cu2+-Fe2+-SO42--OH- system has been proposed.It was found that single-phase nanodispersed powders of cubic copper ferrites with a saturation magnetization Ms 78–93 Emu/g can be obtained by plasma treatment at 300 s and pH 12. Copper ferrite with an admixture of Cu2O is formed at pH = 8.The maximum values of the coercive force correspond to regimes in which the minimum dislocation density is observed. The saturation magnetization depends on the crystallite size. The crystallite size of the resulting powders is in the range of 225–500 A. The results showed that the processing time is the parameter that has the greatest impact on the structural and magnetic characteristics of copper ferrite; the pH of the reaction medium affects them to a lesser extent.

Synthesis and alloying of zinc sulfide in a homogeneous system based on dodecane, its identification and optical properties

Zinc sulfide doped with Mn2+ ions was synthesized in a homogeneous dodecane medium by the method of emerging reagents. By methods of chemical and X-ray phase analysis, IR spectroscopy, electron microprobe microscopy, identification of products was carried out, photographs of the surface of powder particles (SEM) were recorded. Based on the totality of the results, a conclusion is made about the formation of nanoscale objects having a polytype structure with a predominance of distorted cubic crystals forming agglomerates up to 10 microns in size in ZnS powder and up to 100 microns in ZnS–Mn powder. The formation of nanoscale ZnS particles is confirmed by spectral data. The effect of manganese ions on the photoluminescence (FL) of the powder is manifested by a change in the type of the descending branch of the ZnS–Mn FL band, it is associated with recombination processes at the levels of defects formed by Mn2+ ions in the ZnS structure at their low concentration.

Polycation perovskites in the system Ba<sub>2</sub>Y<sub>2</sub>O<sub>5</sub>–BaCuO<sub>2</sub>–BaMoO<sub>4</sub>–BaTiO<sub>3</sub>

To maintain the single-phase nature of the cubic solid solution Ba2(Y,Cu,Mo)2O6, which is prone to polymorphism, titanium oxide was used. As a result of the synthesis by burning the gel, annealing at 1000°C and subsequent cooling in an inertial thermal mode, the cubic modification F3m without an admixture of perovskite Fm3m for the composition Ba5Y2CuMoTiO14 was obtained for the first time. A comparative study of samples Ba4Y2CuMoO11 and Ba5Y2CuMoTiO14 was carried out using the methods of X-ray phase analysis, X-ray fluorescence spectrometry, infrared spectroscopy and diffuse reflectance spectroscopy.

Preparation and properties of conversion phosphate-containing coatings on magnesium alloys doped with rare earth elements

The purpose of our study was to synthesize and analyze the structure, qualitative and quantitative composition, and protective properties of phosphate-containing conversion coatings on WE43, ZRE1, and QE22 magnesium alloys doped with rare earth elements in the Hank’s Balanced Salt Solution. Scanning electron microscopy, energy dispersive X-ray analysis, and X-ray phase analysis methods were used to study the morphology, microstructure, the elemental and phase compositions of QE22, ZRE1, and WE43 magnesium alloys doped with rare earth elements, as well as conversion coatings formed on their surface during phosphating. Linear voltammetry and electrochemical impedance spectroscopy were used to study the kinetic properties of corrosion of the analyzed samples in the Hank’s Balanced Salt Solution (рН = 7.4) imitating the human body environment before and after phosphating. The study showed that the phosphating of magnesium alloys doped with rare earth elements results in the formation of low-soluble fine-grained coatings with a pronounced crystal structure and a thickness from 16 to 21 μm. The obtained conversion coatings are characterized by the following elemental composition: Са ≈ 40 wt.%; Р ≈ 15 wt.%; and О ≈ 35 wt.%. The crystal structure of phosphate-containing coatings is presented by the brushite phase (CaHPO4·2H2O). The electrochemical studies of the corrosion behavior of magnesium alloys in the model Hank’s Balanced Salt Solution (рН = 7.4) demonstrated that the corrosion current density decreases in the sequence QE22, ZRE1, WE43 and is icorr, A/cm2: 5.2·10–5; 2.5·10–5; 2.0·10–5. The obtained conversion coatings based on brushite reduce the corrosion rate of QE22, ZRE1,and WE43 magnesium alloys by 15.2, 7.8, and 6.3 times, respectivel

Determination of the degree of crystallinity of polyphenylene sulfide composited with crystalline and non-crystalline fillers by applying the direct derivation method

A new procedure for determining the degree of crystallinity (DOC) has been recently proposed, and it has been verified using experimental and computer-generated powder diffractometry data [Toraya (2023). J. Appl. Cryst. 56, 1751–1763]. As an application to real materials like engineering plastics, this procedure is here applied to the DOC determination of plate-like polyphenylene sulfide (PPS) samples, composited with crystalline and non-crystalline fillers. The coexistence of partially crystallized polymer with non-crystalline fillers in target materials makes it difficult to separate the non-crystalline part of the partially crystallized polymer. This problem is here solved by the inverse application of the direct derivation (DD) method for quantitative phase analysis (QPA). The intensity–composition (IC) formula used in the DD method can derive the weight fractions of the individual components from just the total sums of observed intensities and the chemical composition data for these components [Toraya (2016). J. Appl. Cryst. 49, 1508–1516]. For the present purpose, the IC formula has been inversely applied to calculate the relative intensity ratios of individual components under the assumption that the chemical compositions and weight fractions of the respective components are known. The total halo intensity could then be separated into the non-crystalline part of the polymer and the non-crystalline filler. Analyzed results of PPS composites in four different DOCs are reported.

Semi-destructive methods for evaluating the micro-scale residual stresses of carbon fiber reinforced polymers

Micro-scale residual stress in carbon fiber reinforced polymers have a significant impact on their mechanical performance. The residual stresses in the carbon fibers were released by micro-slotting and micro-ring-core methods using focused ion beam (FIB). The released deformation fields were captured by cross-gratings and mapped by geometric phase analysis (GPA) and digital image correlation (DIC) methods. The in-plane residual stresses in the carbon fibers were experimentally determined to be −40.5 MPa using elastic constitutive relations, which is consistent with the composites cylinder model. The axial compressive residual stresses in the fibers were found to be greater than −100 MPa. Moreover, the maximum value of residual stress in the polymer matrix was observed at the interface, potentially serving as a crack initiation site.

Unified Solid Solution Product of [Nb][C] in Nb-Microalloyed Steels with Various Carbon Contents.

In this work, the solid solution product of [Nb][C] in the Nb-microalloyed steels with various carbon contents in the range of 0.20~1.80 wt.% was investigated by means of the extraction phase analysis method. The results showed that the Nb content in austenite tended to first decrease and then increase with the increase of carbon content in the steels. A unified solid solution product of [Nb][C] in austenite at different temperatures was obtained according to the results of the experimental steels. The Nb content in austenite of the experimental steels with high carbon contents was lower than that calculated by Ohtani's equation. The existence of NbC precipitates in the case and the core of the specimens carburized at 930 °C and 980 °C were verified by transmission electron microscopy (TEM) observations. The pinning effect of NbC precipitates on austenite grain growth was calculated according to the size and amount of NbC precipitates in the carburized case and the core of the carburized specimens. The calculated results of prior austenite grain sizes were in good agreement with the experimental results, which indicated that the unified solid solution product of [Nb][C] in Nb-microalloyed steels with various carbon contents was applicable for the low-pressure carburizing process.

Влияние технологических параметров процесса прямого лазерного выращивания на качество формируемого объекта из титанового сплава ВТ23

Introduction. Laser engineered net shaping (LENS) or Direct metal deposition (DMD) is considered as a promising method for manufacturing products of complex configurations from titanium-based alloys, as it allows minimizing the use of machining and loss of material to waste. Currently, neither the LENS technological process of titanium alloy VT23 has not been developed, nor the structural features of the alloy after LENS have not been studied, which will make it possible to determine the scope of application of the material after LENS. The purpose of this study is to determine optimal modes of the LENS process for manufacturing of quality parts from titanium alloy VT23. Methodology. The alloy specimens obtained with laser power 700÷1300 W in increments of 100 W and scanning speed 600÷1,000 mm/min in increments of 200 mm/min and distance between adjacent laser tracks 0.5–0.9L (L — track width) in increments of 0.2L were analyzed in the study. The elemental composition of the powder material was studied by X-ray fluorescence analysis and reducing combustion in a gas analyzer, the structure of the objects obtained by LENS was analyzed by metallographic and X-ray phase analysis methods as well as microhardness was determined. Results and discussion. It is established that high-quality objects without cracks, with low porosity can be synthesized from VT23 alloy by LENS method using the following modes: laser power 700÷1100 W, scanning speed 800–1,000 mm/min, track spacing 0.5–0.7 of the individual track width L. It is shown that after all investigated LENS modes, the VT23 alloy had a dispersed (α+β) structure of the “basket weave” type. It is revealed that regardless of LENS mode the amount of β-phase in the alloy structure is about 30 %. It is shown that the microhardness of the deposited material does not depend on LENS modes and is 460 HV.