Inorganic Materials: Applied Research最新文献

The unique properties and possible fields of application of submicron powders from refractory oxides obtained by aerosol-spray pyrolysis are considered. Analysis of experimental results obtained by researchers at different times convincingly proves the prospects of using nonagglomerating aerosol submicron spherical powders to produce ceramic materials with a high-density, uniform, and fine-grained structure that does not contain pores. The uniqueness of aerosol powders is due to the presence in particles of a nanopolycrystalline substructure with a developed network of grain boundaries, which during the sintering process, has a significant impact on the efficiency of diffusion mass transfer and promotes to increase the rate and completeness of pore overgrowth. Aerosol powders acquire these properties through the use of ultrasonic spray pyrolysis, where equilibrium physical and chemical processes occur in ultra-small local volumes of aerosol droplets ensuring a high degree of homogeneity of the resulting powder. Being formed ultra-thin substructure of aerosol powders ensures their complete sintering at low temperatures allowing the formation of a high-density, nonporous ceramic material with extreme physical and mechanical characteristics. The practical use of nanostructured aerosol powders does not require the use of operations related to their preliminary preparation (grinding–crushing, classification, purification from impurities, etc.), and, unlike ultrafine powders, such powders are easily molded using traditional methods of powder technology (uniaxial pressing, hot casting, etc.).

The features of self-propagating high-temperature synthesis (SHS) in combustion and electrothermal explosion modes from a powder mixture of Ti + B + 10 wt % TiH₂ were experimentally investigated. The type of mechanism for the formation of condensed products was determined for each mode. It was found that, in the SHS process for this composition, regardless of the synthesis mode, an equilibrium mechanism is realized. A comparison of the phase composition of products for the two modes was conducted. It was experimentally confirmed that there is a fundamental possibility for multicomponent mixtures, where an equilibrium mechanism is realized, to synthesize products with the same phase composition but different morphology (sintered or melted).

The effect of different concentrations of fly ash aluminosilicate cenospheres on the structure and properties of elastomeric composites is studied. Composite materials based on ethylene–propylene–diene rubber (EPDM-40) with different mass fractions of fly ash (10, 20, 30%) are obtained using laboratory rollers. The microstructure of mixtures of EPDM and aluminosilicate cenospheres is studied by optical microscopy. It is shown that the concentration of the filler of more than 30 wt % increases the concentration of larger cenosphere agglomerates in the structure, which indicates interfacial separation in the mixtures, which is probably associated with the fact that mechanical mixing on mixing equipment does not make it possible to achieve uniform distribution of the filler throughout the elastomeric matrix. The appearance of new absorption bands in the region of 1400–800 cm^–1 that correspond to the stretching vibrations of Si–O–Si present in aluminosilicate cenospheres is detected in the IR spectra. According to the thermogravimetry data of the compositions under study, the introduction of aluminosilicate cenospheres promotes a slight increase in the thermal stability of the composition under study with the concentration of cenospheres of more than 30%. The influence of the concentration of aluminosilicate cenospheres on the resistance of the composites to aggressive media is analyzed, and it is found that the introduction of a cenosphere filler in the amount of 10 to 30 wt % into mixtures based on EPDM can increase the oil and petrol resistance of the materials.

The effect of cathodic embedding chromium into zinc coating layers is analyzed from the standpoint of change in corrosion resistance. The zinc is deposited from electrolytes of various compositions on electrodes made of St3 steel grade. Grade TsO zinc is used as anode. The preliminary treatment of steel electrode involves treating the surface in the prephase potentiostatic embedding (PPD) mode at a potential 50 mV more positive than equilibrium zinc potential E_eq of the working electrolyte for 5 min. The zinc coating layer is deposited in potentiostatic mode at a potential of –1.20 V relative to the silver chloride reference electrode. The introduction of chromium into the electrodeposited zinc coating is made from electrolytes containing a trivalent chromium salt. The results of X-ray fluorescence analysis of the components of working electrodes after cathodic introduction of chromium, as well as the morphology of the surface formed, are explored using the scanning electron microscopy indicating the presence of chromium in the coating and its effect on the structure. The corrosion resistance of zinc coating layers modified through cathodic introduction of chromium at potentials of –1.05 and –1.10 V for 5 min is better than in chromated zinc.

The physical and mechanical characteristics of cured synthetic thermosetting resins before and after electric pulse treatment with nanosecond electromagnetic pulses (NEMP) have been studied: water absorption, surface layer energy (surface tension), tensile strength. The efficiency of electric pulse treatment of cured polymer binders with NEMP to increase strength and reduce moisture absorption of materials has been confirmed. The optimal irradiation regime of cured resins with nanosecond electromagnetic pulses has been established: pulse repetition frequency of 1000 Hz, pulse amplitude of 15 kV, irradiation duration of 10 min. Implementing this irradiation regime with NEMP results in an increase in the strength limit of samples (for epoxy resin by 12.8%, for vinyl ester resin by 18.6%, for polyester resin by 21.1%) and a decrease in water absorption of samples (for epoxy resin by 25.6%, for vinyl ester resin by 21.6%, for polyester resin by 16.4%).

Abstract—An analysis of current trends and opportunities for the application of artificial intelligence (AI) in materials science and concrete technology, including 3D printing in construction, is presented. The key role of AI in predicting material properties, developing new materials, and quality control is highlighted. By analyzing large volumes of data collected from numerous studies, AI can suggest optimal parameters to achieve desired material properties, thereby reducing costs and increasing production efficiency. Existing rheological models, such as the Bingham–Shvedov model or the Herschel–Bulkley model, describe material behavior based on specific equations and parameters. These models can be useful in predicting concrete properties, especially when data on its component composition is available. However, these models may be limited in their predictive accuracy, particularly for nonstandard or novel materials. It has been found that machine learning and neural networks have the potential to provide accurate predictions of rheological and physicomechanical properties of concrete materials, considering multiple parameters that influence material characteristics, including chemical and mineralogical composition, as well as structural features. The combination of experimental data and AI can successfully optimize compositions and properties during production, reducing costs and research/testing time, and opening new opportunities for researchers and engineers in the field of materials science. Machine-learning algorithms such as XGBoost, LightGBM, Catboost, and NGBoost demonstrate high predictive accuracy and have become powerful tools in the design of concrete compositions and innovative technologies. The analysis of Shapley additive explanations allows us to understand which parameters of a concrete mixture have the greatest influence on its characteristics.

N,N'-Diglycidyl-1,3-bis(carboxymethylestersulfoimide) of 2-hydroxypropyl saccharin-6-carboxylic acid is obtained by interaction of dipotassium salt of 2-hydroxypropyl-1,3-bis(carboxymethylestersulfoimide) of saccharin-6-carboxylic acid with epichlorohydrin. The structure of the epoxy-imide compound is confirmed by the data of IR spectroscopy. A thermostable hot-curing epoxy-imide composition is made on the basis of the obtained resin. A composition based on an ED-20 epoxydiane resin is also made for comparative estimation of the heat resistance of the obtained oligomer. The curing process of the composition is studied by differential thermal analysis on a derivatograph of the Paulik–Paulik–Erdey system. It is found that the degree of cure of the obtained composition under the optimal regime of curing reaches 82%. It is determined that the composite material based on the epoxy-imide resin is characterized by sufficiently high thermal indices in comparison with materials based on an ED-20 resin and can replace them in those areas where heat-resistant epoxy compounds are needed and can also be used to produce heat-resistant epoxy adhesives and coatings.

A search for an optimum technique for studying the electrical characteristics of thin n/p-InxGa_1–xAs semiconductor layers with different doping levels has been carried out. The primary task has been to measure the main electrical characteristics by different methods using resistivity (conductivity), majority carrier concentration, dependence of the main electrical parameters on the doping type and level, and their comparison. Using the example of the p- and n-In_0.01Ga_0.99As solid solutions grown by MOCVD, a technique for studying the main electrical characteristics of the epitaxial layers has been proposed, which takes into account the estimated homogeneity on large-area samples. Results obtained by different methods, including photoluminescence, contactless surface resistivity measurement, van der Pauw (Hall effect), electrochemical capacitance–voltage profiling, and in situ control, have been compared. Basing on the results obtained and comparison with the literature data, conclusions have been drawn concerning the need, sufficiency, and complementarity of the methods for controlling and studying semiconductor epitaxial structures.

The process of frictional processing of a plasma coating made of R6M5 steel on a cylindrical substrate has been developed and studied. Friction processing was carried out for 10–70 s by cyclic application of pressure of 30 MPa of two tools made of R18M5 steel on a coating rotating at a speed of 900 rpm, including additional movement of tools along the generatrix of the cylindrical substrate. With an increase in the friction treatment time, the coating surface temperature rises to 1202°C, which is sufficient for plastic deformation of the coating material. The coating microhardness after plasma spraying is 3.13 GPa; after friction treatment, it increases to 7.64 GPa. The large degree of deformation of the upper layers of coating under the action of tools determines the increase in the microhardness of the coating from the substrate to the free surface from 5.85 to 7.64 GPa.

Composite zirconium–titanium–silica sorbents with SiO₂ content of 10–30 wt % were synthesized on the basis of products of hydrochloric acid decomposition of eudialyte concentrate and their surface modification into H⁺ and Na⁺ forms was carried out. All samples were studied by methods of chemical, X‑ray phase, Brunauer–Emmett–Teller (BET), and Barrett–Joyner–Halenda (BJH) analyses. It is shown that all obtained samples of silica-containing Zr–Ti–SiO₂ sorbents are mesoporous. The pores are predominantly wedge-shaped with open ends, and pores with a diameter of 10–50 nm (~50% of the total pore volume) have the maximum volume. Based on the obtained values of the specific capacity of the adsorption monolayer of the surface of SiO₂ samples and the value of Gibbs energy change (ΔG°) in the process of nitrogen sorption, it was concluded that the surface modification of synthesized Zr–Ti–SiO₂ sorbents does not affect the physicochemical properties of their surfaces and the mechanism of nitrogen sorption. The sorption activity of synthesized samples towards Cu²⁺, Co²⁺, and Sr²⁺ ions was studied by the static method. It was found that modification of the obtained samples into the H⁺ form has less influence on their sorption capacity than their conversion into the Na⁺ form, does not depend on their SiO₂ content in the range of 10–30%, and decreases in the Cu²⁺ → Co²⁺ → Sr²⁺ series.