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The change of geochemical properties of ferric hydroxide nanoparticles under the influence of a weak magnetic field was investigated. Ferric hydroxide nanoparticles formed as a result of the interaction of iron-containing minerals with natural aqueous solutions are of importance for geochemical processes, especially hypergenesis, sedimentation, and soil formation. The hydrolysis of ferric chloride in hot water (t = 70-75°С) was used to obtain ferric hydroxide nanoparticles under laboratory conditions. The nanodispersion (colloidal solution) was exposed to a weak pulsed magnetic field. The spectrophotometric properties of the colloidal solution of ferric hydroxide were determined using an SF-46 spectrophotometer in the wavelength range of 320-610 nm. The size of colloidal particles was calculated by a method based on the theory of Rayleigh light scattering. The size of colloidal particles depended on the exposure duration of a pulsed magnetic field on the colloidal solution. The size of colloidal particles was due to a change in the magnitude of the diffuse ionic atmosphere under the influence of a pulsed magnetic field. The kinetic stability of the colloidal solution was evaluated by the coagulation threshold, which was determined visually by the appearance of the turbidity of ferric hydroxide colloid when adding NaCl solution. The kinetic stability of a colloidal system was determined by the size of colloidal particles. These results can be used to better understand certain hypergenesis, sedimentation, and soil formation processes.

The article is devoted to the development of nanosized sorbents for the removal of cesium and strontium, as well as heavy metal ions simultaneously present in a multicomponent two-phase solution containing complexing agents and surfactants. Magnetically sensitive nanosorbents are currently considered promising since the influence of external fields can improve the performance of the developed sorbents. To create magnetically sensitive nanoparticles and composites based on them, we used carbon-coated nanoparticles of metals in a composition with montmorillonite. The scanning electron microscopy revealed that the use of electric hydraulic discharge to increase the efficiency of sorbents had not led to a positive result because the high voltage electric pulse passage through the aqueous dispersion causes the carbon shell disintegration, while the metal nanoparticles form aggregates as a result of the partial melting. The use of the pulsed magnetic field in the synthesis of a nanosized composite based on montmorillonite and magnetite is explained by the influence of the magnetic field on the particle size. It has been ascertained that the size of the nanoparticles changes depending on the duration of the magnetic field interaction with the aqueous dispersion. At the beginning the particle size slightly decreases, and then it increases. The obtained nanosized composite allows to remove cesium-80%, strontium-90%, iron-99%, cobalt-97%, and manganese-98% from a multicomponent two-phase solution containing simultaneously cesium, strontium, cobalt, manganese, iron and organic substances, including surfactants and complexing agents. The results of the research allow us to recommend using nanosized magnetically sensitive composite based on magnetite and montmorillonite for the purification of multicomponent technogenically polluted waters.

Oil spills necessitate the development of effective methods for preventing their damaging effects on the environment. A number of physical, chemical, thermal, and biological methods are used to combat oil spills. Among them, sorption is considered to be efficient in removing thin oil films from water surfaces. Currently, there is an urgent need for simple methods of obtaining oil sorbents that include a magnetosensitive component to optimize the process of removing oil from the water surface. The purpose of the work is to obtain and research oil sorbents resistant to destruction, with increased bulk density and complex magnetosensitivity, based on thermally expanded graphite (TEG) with the inclusion of micro- and nano-particles of iron and its oxides. The structure and composition of the new composite material was characterized using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffractometry, thermogravimetric analysis, and laser diffraction particle sizing. The composite sorbent comprised TEG with the inclusion of iron-containing magnetosensitive particles. Metal-carbon nanoparticles (MCN) were used as the magnetosensitive component; they had a magnetosensitive iron core covered with a carbon shell. We used two methods of synthesis, namely (i) mechanical mixing of the TEG flakes and MCN particles, and (ii) applying a thermal shock (microwave processing) to the mixture of graphite intercalated with sulphuric acid and micro- and nanoparticles of iron and iron oxides. In the first case, MCN particles were fixed on the faces, edges, and other surface defects of the TEG flakes due to intermolecular forces, coordinate bonds, and electrostatic interaction. The strong adhesion of magnetosensitive iron/iron oxide and TEG particles in the second case was due to the mutual dissolution of iron and carbon components during the thermal shock, which formed an interfacial layer in which iron carbide is present. The presence of magnetosensitive components in the structure of the proposed oil sorbents allows the use of magnetic separation for the localization and removal of oil spills, increases the density of sorbents, and, accordingly, leads to a decrease in windage while retaining the advantageous properties of thermally expanded graphite. According to the results of laboratory studies, the efficiency of removing oil from the water surface is not lower than 95–96%.

Titanium aluminides have a low density and maintain high strength at elevated temperatures, which makes them prom-ising for the manufacture of aircraft engine elements. In the presented work, the problem of welding in the solid phase ortho-rhombic titanium aluminide based on the intermetallic compound Ti2AlNb and heat-resistant alloy ЭИ437Бon a nickel base is considered. A review of the state of the problem of welding heat-resistant alloy ЭИ437Бbased on nickel and titanium or-thoaluminide Ti2AlNb was carried out. It was established that the main problem in welding Ti2AlNb alloy with nickel alloy is a strong tendency to the formation of brittle phases in the joint zone, which negatively affect the mechanical properties. A promising method of joining this group of alloys is diffusion welding in a vacuum.The purpose of the work is to study the influence of multilayer and gradient foil on the formation of the zone of titanium orthoaluminide joints with a nickel-based alloy during vacuum diffusion welding.In the work, multilayer and gradient foil based on Al-Ni and Ni-Tisystems were used according to the original structure. The foils were obtained by electron beam evaporation and condensation in a vacuum. The deposition process consists in the layer-by-layer condensation of elements on a horizontal substrate.The work presents the method of conducting experiments, welding modes, chemical composition of materials and foil.The work shows for the first time that during the direct welding of titanium orthoaluminide with the ЭИ437Бalloy, as a result of the strong tendency ofthe materials to form brittle phases at the joint, a significant increase in microhardness is observed in the joint zone up to 2...4 times compared to the base material (up to 11.94 GPa). It was established that the useof layered foil (Ni/Ti, Al/Ni) as intermediate layers allows to significantly reduce the difference in microhardness values in the joint. At the same time, the microhardness in the central part of the joint zone reaches 6.69...8.79 GPa, which is close to the microhardness values of Ti2AlNb.The presented materials can be used as a basis for the development of welding technologies in the solid phase of heter-ogeneous titanium orthoaluminide materials with nickel-based alloys.