Inorganic Materials: Applied Research最新文献

Materials based on selenite-substituted hydroxyapatite and collagen were synthesized. Chemical analysis of solutions after precipitate separation confirmed the substitution of phosphate ions by selenite ions in the hydroxyapatite structure. Results of elemental analysis, X-ray phase analysis (XRD), and infrared spectroscopy (IR) verified these substitutions in the hydroxyapatite structure. Morphological studies revealed a trend of increasing aggregate size with higher concentrations of selenite ions and collagen. Scanning probe microscopy showed that samples with selenite ions exhibited greater surface roughness compared to collagen-containing samples. The BET (Brunauer-Emmett-Teller) method provided specific surface area measurements of synthesized powders. The highest values were recorded for samples with 10.0 g/L selenite ions, while the lowest were for collagen-containing materials. Resorption studies in TRIS-buffer (pH 7.40) and simulated body fluid (SBF) demonstrated increased dissolution rates for samples with high selenite ion content. Collagen addition reduced dissolution rates. Thermal analysis (200–800°C) identified the sample with lowest selenite ion concentration (1.5 g/L) as most thermally stable.

The problem of developing effective methods for predicting the defining characteristics of polymer composites under the influence of extreme environmental factors characteristic of the climatic conditions of the Arctic and Subarctic zones has been investigated. The formulated problems of developing effective forecasting methods are investigated within the framework of refined variational formulations based on modern provisions of the kinetic theory of strength. A number of fundamental principles and concepts were introduced that make it possible to optimally coordinate the defining parameters calculated on the basis of the constructed mathematical models at the macro level with the defining parameters of physical models describing molecular interactions at the micro level. A methodology has been developed for matching the parameters of mathematical and physical models at the micro and macro levels, which made it possible to solve the problem of restoring the parameters of physico-chemical processes occurring at the micro level, leading to destructive changes in composites and deterioration of their characteristics over time. Based on the conducted physical experiments, an objective assessment of the parameters of destructive chemical reactions in composites was carried out, which made it possible to construct effective generalized models of durability for a long-term period, as well as to conduct a constructive analysis of the influence of individual extreme factors on durability. The results of computational experiments are presented.

This paper presents research on the methylation of silicon dioxide surfaces derived from sulfuric acid decomposition of nepheline concentrate. Two methylation approaches were investigated: (1) direct attachment of methyl groups to the silica surface in nonpolar media with water molecule condensation, and (2) intermediate formation in an alkaline medium. Through comprehensive physicochemical characterization, we analyzed the morphology, surface elemental composition, and structural-surface properties of the methylated silica samples. The study revealed that silica subjected to direct methanol treatment exhibits a higher specific surface area (496 m²/g) compared to the sample prepared via alkaline intermediate formation (278 m²/g), likely due to the more complex synthesis mechanism of the latter. IR spectroscopy confirmed the presence of characteristic –C–H and –C–C-bond vibrations, indicating successful surface methylation. These findings, supported by porometry data, demonstrate partial hydrophobization of the silica surface and enhanced affinity for nonpolar organic compounds. The results suggest potential applications in developing membrane filters for organic compound separation.

In this work, the effect of a polar nanoporous matrix of barium titanate on the phase transition temperatures of embedded thiourea was investigated. An increase in the ferroelectric-paraelectric transition temperature of embedded SC(NH₂)₂ has been detected. This is explained by the fact that due to the higher coefficient of thermal expansion for thiourea compared to barium titanate, when the temperature drops from room temperature (not stressed) to 178 K (stressed), the compression of thiourea crystals occurs faster than barium titanate.

Magnetic nanoparticles of maghemite (γ-Fe₂O₃), cobalt (CoFe₂O₄), and zinc ferrites (ZnFe₂O₄) with varied size and morphology were synthesized by means cryochemical technologies. The synthesis route involved cryogenic spray drying of organic metal salts followed by their subsequent thermal decomposition. The use of iron(II) gluconate and iron(III) ammonium citrate as precursors results in the formation of micron-sized maghemite macroporous particles and 50–150 nm nanoparticles aggregated into micron-sized plate-shaped structures, respectively. Both maghemite samples exhibited an admixture of goethite. If solutions of iron acetylacetonate with zinc or cobalt acetate are used as precursors, then ZnFe₂O₄ nanoparticles with average size 10 nm and CoFe₂O₄ nanoparticles with average size 15 nm are formed.

Evolution of textural compositions in aluminum alloys during bending is studied. The change in crystallographic texture in billets and samples after bending of two materials is analyzed using X-ray diffraction. It is shown that bending leads to the formation of an anisotropic texture with a dominance of shear-type components. Particular attention is paid to the role of recrystallization nuclei in the reorientation of the grain structure. The relationship between texture evolution and mechanical properties of materials is also analyzed. It is experimentally established that the ductile A5 alloy is characterized by an ordered transformation of texture during bending. In contrast, in the high-strength 1565ch alloy, bending leads to texture blurring with an increase in the textureless fraction, which is due to the heterogeneity of deformation. The results of the study are of practical importance for predicting the mechanical properties of aluminum alloys after bending and optimizing the technological parameters of processing.

The paper deals with Lüders deformation in an aluminum-magnesium alloy with structural heterogeneity in the form of a friction stir weld. It is found that a complex structural state due to the weld seam causes two zones in the specimen: the base metal where Lüders deformation occurs and the stir zone where deformation does not localize. Thermomechanically affected zones with increased microhardness compared to the base metal and stir zone are sources of Lüders deformation fronts. Depending on the strain rate, deformation fronts can move intermittently or continuously. The kinetics of fronts is determined by the response of active deformable media to external mechanical action and can be described within the autowave concept of plastic deformation similarly to homogeneous materials.

Functionally organized steel-aluminum compositions were manufactured by liquid and solid phase methods, namely arc, friction surfacing, and explosion welding processes. The influence of the manufacturing process on the characteristics of the diffusion zone separating the pure aluminum functional layer and the steel substrate has been determined. It has been established that a layer of Fe_xAl_y double intermetallic compounds of different stoichiometric composition is formed between the functional layer and the substrate. It has been shown that this layer is characterized by a discrete nature and an average thickness of 16 µm in compositions manufactured by the explosion welding process. The use of arc or friction surfacing processes leads to the formation of a continuous intermetallic layer with an average thickness of 8.2 and 2 µm, respectively. The level of adhesive strength of manufactured functionally organized steel-aluminum compositions was assessed in order to determine their properties.

This work performed a detailed characterization of the chemistry of the vancomycin-loaded PLGA-CaP composite coatings with different PLGA concentrations (5, 8, 10 wt %) on titanium implants for controlled sustained drug delivery. The lower CaP layer had a complex porous morphology with numerous branched pores and pore channels, and spheroidal elements on the surface, into which the antibiotic vancomycin was effectively loaded. The upper dense homogeneous PLGA layer partially penetrated the near-surface pores with drug. A gradient elemental composition (Ca, P, Ti, O, C) along the thickness and the homogeneous elemental distribution on the surface of all the vancomycin-loaded PLGA-CaP composite coatings were revealed. The vancomycin-loaded CaP coatings included strong P–O and P–OH bonds, while the composite vancomycin-loaded PLGA-CaP coatings were characterized by –C=O, –COO and C–O–C bonds. The formation of strong chemical bonds between the drug and the carrier components was confirmed by the alterations and broadening of the C1s, O1s, Ca2p and Ti2p peaks. This may be a favorable factor for efficient controlled sustained drug delivery.

The paper proposes an innovative method for express assessment of the InGaAs/InP epitaxial structure parameters with SCAM architecture. As the result of the work, an InGaAs/InP heterostructure was grown, models for verification were developed, tests were performed to assess the characteristics of the epitaxial structure and real characteristics were compared with simulated results.