Inorganic Materials: Applied Research最新文献

Abstract—The possibility of synthesizing inorganic thermofoam silicate vitrified materials from technogenic and natural raw materials has been studied and substantiated. Compositions and modes for obtaining quality products have been selected. On the basis of microsilica and nepheline concentrate with the addition of chalk and gypsum, thermofoam silicates with a density of 0.49–0.52 g/cm³, a strength of 2.7–3.10 MPa, a reduced thermal conductivity of 0.059–0.062 W/(m K), and a water absorption of 12–18% have been synthesized.

Abstract—Changes in limiting interlayer shear stresses in a loaded cured carbon-fiber plastic after exposure to a microwave electromagnetic field with a frequency of 2450 MHz at different energy flux densities have been studied with allowance for the temperature factor and time. It is shown that, at a rational combination of the energy flux density and time ((17–18) × 10⁴ μW/cm² and 2 min, respectively), the limiting stresses increase by 17% on average as compared with the references samples.

Abstract—Powders and ceramic composite materials in an Al₂O₃–ZrO₂ system with a concentration of ZrO₂ of 20 wt % are obtained. The effect of introduction of chromium oxide and yttrium oxide into Al₂O₃–ZrO₂ ceramic materials on the phase composition, porosity, microstructure, and mechanical properties is studied. It is shown that the introduction of chromium oxide leads to the improvement of sintering and mechanical properties of the ceramic. Products with the predefined shape of a corresponding computer model are obtained by 3D printing, and also their multistage thermal treatment is carried out. Densely sintered ceramic materials are obtained at 1550 and 1600°C, the open porosity of which is below 1% and microhardness is up to 1646 ± 50 HV. The samples are characterized by a dense microstructure with the grain size of zirconium dioxide from 400 nm to 2 μm and of aluminum oxide from 800 nm to 3 μm. The thickness of the layer formed during 3D printing shows a positive impact of the addition of Cr₂O₃ on the resolution during 3D printing.

Abstract—A study of the features of the formation of a diffusion layer in beryllium-containing steel VNC32-VI during vacuum nitriding and carburization is carried out. It is established that saturation with carbon and nitrogen makes it possible to remove delta-ferrite from the structure. The sequential combination of nitriding and carburization, owing to the formation of a structure on the surface of the samples that is more favorable for the diffusion of interstitial elements, ensures an increase in the total thickness of the diffusion layer by 5–10 times greater compared with the thickness values for individual treatments.

By the example of α-Fe₂O₃ hematite, 5Fe₂O₃⋅9H₂O ferrihydrite, and γ-Fe₂O₃ maghemite powders, a microwave-radiation-induced powder system temperature growth ΔT_max of several degrees has been measured in the ferromagnetic resonance mode at a frequency of 8.9 GHz. The powders heat up the most in the external field H coinciding with the ferromagnetic resonance field. The value of the ΔT_max effect depends on the magnetization of a powder material. The results obtained allow us to propose a new magnetic hyperthermia method for biomedical applications.

Abstract—The technology of preparation of cladding materials based on mechanically activated cullet modified with sodium and potassium hydroxides has been developed. The phase composition and macro- and microstructure of the cladding materials are studied. The structure of the composite modified with potassium hydroxide is found to consist of needle-shaped and columnar crystals in the interporous space, while lamellar crystals are formed in the NaOH-modified composite. The physicomechanical properties of the cladding materials are studied.

Abstract—Nonwoven fibrous materials based on polylactide (PLA) and ozonide of oleic acid triglyceride (glycero-(9,10-trioxolane)-trialeate) in a range of concentrations of 1–5 wt % intended for hygienic and medical devices are obtained by electrospinning. The introduction of ozonide leads to plasticization of PLA, which manifests itself in the cleavage of the primary jet of the forming solution and appearance of ultrathin nanofibers; here, the porosity and relative elongation at break increase. The optimum weight fraction of ozonide introduced into PLA is determined to be 3 wt %.

Abstract—The review presents publications devoted to a promising biopolymer, poly-3-hydroxybutyrate, and composite materials based on it. The structure and properties of the materials are considered. The main focus is on the biomedical application of these biopolymer materials. The main advantage of poly-3-hydroxybutyrate is its biodegradability in nature and living systems, biocompatibility, hemocompatibility, and thromboresistance. This biopolymer also possesses processability. The products and materials based on it can be processed by solution and melt production methods. The review pays great attention to the production of ultrathin fibers by electrospinning. Materials based on poly-3-hydroxybutyrate even now find wide application in medicine, hygiene, packaging, and ecology.

The results of the stepwise-dilatometry study of the influence of the graphite content on the temperature dependence of the specific volume of nanocomposites based on high-density polyethylene and graphite are presented. It has been found that, for nanocomposites with the graphite content of 1.0–10 wt %, the first-order phase transition occurs at 115°C. For samples containing 15–20 wt % graphite, this transition occurs at 110°C. On the basis of the dilatometric curves, the glass transition temperatures of the nanocomposites have been determined. The kinetics and mechanism of crystallization of nanocomposites have been considered.

Abstract—The possibility of using finely dispersed additives made of local mineral raw materials for the manufacture of concrete based on sulfur binder has been established. At the same time, additives with a high specific surface area contribute to the formation of uniform small sulfur crystals on the surface of fine fillers, which makes it possible to improve the strength properties of sulfur concrete.