Inorganic Materials: Applied Research

Titanium monoboride–titanium composite powders with the titanium matrix content from 20 to 60% are obtained by self-propagating high temperature synthesis (SHS) in titanium and boron powder mixtures. The SHS powders are used for cladding of coatings with a thickness of up to 3 mm on a VT1-0 titanium sheet by electron beam facing. The phase composition and microstructure of the initial powders and cladded coatings are investigated via X-ray diffraction analysis and optical and scanning electron microscopy. On the basis of the microstructure investigation and microhardness profiles in the coating/base plate transition zone, a conclusion about effective adhesion of the coating to the base plate is made. The dependence of the hardness and abrasive wear resistance of the cladded coatings on the phase composition of the powders used for cladding is studied. It is found that the hardness of the coatings strengthened by needle-like titanium monoboride inclusions in the titanium matrix is 2.2-fold higher and abrasive wear is 3.7-fold higher when compared to the properties of VT1-0 titanium. Here, the effect of strengthening and increase in the wear resistance of the titanium matrix by titanium monoboride particles is much smaller than similar effects in the case of the use of disperse titanium carbide particles as the strengthening phase in cladded coatings.

Composite Cu–Cr–N alloys were obtained in situ under vibration of “copper melt–chromium powder” compositions before their crystallization. Two types of alloys were prepared, where chromium powder was freely dispersed or compacted into a tablet. Atmospheric nitrogen was used as a source of chromium nitrides in the alloys. The microstructure of the alloys is represented by a copper matrix hardened with chromium particles and numerous inclusions of nonstoichiometric chromium nitrides Cr₂N_1 – x. Thermodynamic modeling showed that the composition and quantities of chromium nitrides in the Cu–Cr–N alloy depend on the partial pressure of nitrogen above the melt.

Scientific and engineering problems in development of catalytically active compositions for immobilized catalyst systems for steam conversion of hydrocarbon feedstock to hydrogen fuel have been considered. Processes for synthesis of catalytic powder mixtures and production of functional coatings based on them with the use of a promising method of supersonic cold gas-dynamic sputtering have been studied. The data of experimental study in the field of development of catalysts for methane steam conversion to hydrogen-containing fuel on the Cr15Al15 tape support using as starting materials Ni–Al–Al(OH)₃–Ca(OH)₂–Mg(OH)₂ composite powder mixtures are given.

At present, 75–80% of the current operating costs of conventional transport are expended for fuel. According to the International Maritime Organization, the world fleet burns 300 million tons of fuel annually, releasing into the atmosphere 960 million tons of СО₂ and 9 million tons of SO₂. As a result of fouling, the speed of ships may decrease by 50%. By 2020, without new technologies that reduce fuel consumption, air emissions can grow 40%, taking into account constantly increasing volumes of traffic. Therefore, defense methods against marine overgrowth are an urgent topic, and many leading firms are developing antifouling solutions. The paper considers the main means of protection against fouling with the help of polymer coatings, namely, contact active coatings, nonleaching coatings, self-polishing coatings, and non-biocidal coatings. The mechanism of using polymer coatings, as well as their advantages and disadvantages, is described.

A simple and environmentally safe method for obtaining stable nanoparticles of metal sulfides nanoparticles—NpAg₂S, NpCdS, and NpZnS—was developed using different strains of microorganisms in an aqueous solution of metal salts and sulfur sources at the National Research Center Kurchatov Institute—GosNIIgenetika. The concentration of nanoparticles is 1‒4 mg/mL in aqueous suspensions. Using the methods of electron microscopy, spectrofluorimetry, and dynamic light scattering, the main characteristics of biogenic nanoparticles were determined: shape, size distribution, crystal structure, effective diameter, luminescent spectrum, and zeta potential. According to their characteristics, these nanoparticles are referred to quantum dots. It is established that the stability of nanoparticles in aqueous suspensions is due to protein molecules adsorbed on the surface of nanoparticles, which are supplied by cells of microorganisms. Effective immobilization of biogenic nanoparticles on the surface of various polymer supports was carried out. Biogenic nanoparticles along with nanoparticles obtained by physico-chemical methods can be used as fluorophores for imaging of biological processes, also as photocatalysts, solar cells, and for new nanocomposite materials.

The present work is aimed at solving an urgent scientific problem of creation of high-strength and water-resistant dielectric glass-reinforced hot pressed glasses using bi- and polyfunctional epoxy amine binders and fiberglasses from alkalineless, quartz, and silica glasses, as well as their use in shipbuilding.

Using scanning electron microscopy, electron probe microanalysis, and infrared spectroscopy, we comprehensively studied changes in the microstructure and chemical composition of the surface layers of the PM-1E polyimide film, as well as the substances condensed on it, which for a long time (1218 days) was exposed at the Mir orbital space station. It was shown that, during the exposure in space, the microstructure and chemical composition of the film changes only in the first layer of the packet and that no such transformations are observed in the layers located below. On the open surface of the first layer of the polyimide film, new phase formations of various shapes and sizes with both film and needle-like structures differing in chemical composition were discovered. It was found that the condensed matter formed consists of compounds involving silicon, iron, copper, zinc, chlorine, potassium, and calcium, which are likely to precipitate from the own external atmosphere of the orbital station.

The results of the development of a three-layer polymer composite material for hull structures operating in a marine environment with an organic plastic middle layer are considered. The physicomechanical properties of the organoplastic are studied to justify the choice of starting materials, the structure, and the technology for its manufacture.

The paper shows the research results of the structure and mechanical properties of welded joints of the hot-pressed panels and profiles manufactured by JSC Arkonik SMP from aluminum–magnesium 1565ch alloy at the temperature range from –165 to 150°C. It is established that the nature of changes in the properties of welded joints of pressed panels and profiles of 1565ch alloy made by manual argon arc welding with non-consumable electrodes of TIG with filler material СвАМг61 at various test temperatures is similar to changes in the welded joints of rolled sheets. When the test temperature is lowered, low-temperature hardening of the welded joints is observed—at cryogenic temperature (–165°C), 20–30% of strength is gained compared to 20°C. The prolonged aging of welded joints at an elevated temperature (150°C) leads to a decrease in strength by 25–30% compared to 20°C. The strength coefficient of welded joints with reinforced joint is not less than 0.9 of the actual strength of the base metal at all test temperatures.

The paper presents microstructural studies of specimens cut from fuel elements made of E110 spongy zirconium-based alloy after operation in a VVER-1000 before reaching the burnup of ~35 MWd/kg U. As a result of exposure to high temperatures and neutron irradiation, significant changes in the phase composition of fuel cladding materials appear: change in the size, density, and composition of β-Nb particles; change in the composition of the Laves phase; formation of dislocation loops of α type, as well as δ and γ hydrides. The main structural elements determining the degradation of the mechanical properties of the E110 alloy under irradiation are dislocation loops and fine-phase precipitates owing to their relatively large density. The data obtained can be used to construct dose dependences of microstructural changes with the aim of predicting the residual life of claddings and fuel assemblies as a whole.

The paper presents an overview of the basic principles of extending the lifetime of BN-600 fast reactors. These principles based on analysis of the main in-service mechanisms of material embrittlement and damage underlie the normative documents of the Rosatom State Corporation and were used by the authors in their developments for justification of the design lifetime of the BN-800 and BN-1200 fast reactors. The so-called critical events and limit states that determine the structural integrity and lifetime of fast reactor components have been formulated. On the basis of the results of this work, the repost “Basic Principles for Lifetime and Structural Integrity Assessment of BN-600 and BN-800 Fast Reactor Components with Regard to Material Degradation” was made at the International Conference on Fast Reactors and Related Fuel Cycles: Next Generation Nuclear Systems for Sustainable Development (FR17) held by the IAEA in Yekaterinburg in 2017.

One of the main operability criteria for fuel subassemblies (FSAs) in sodium-cooled fast reactor cores, i.e., the criterion of tolerable shape change in the hexagonal wrapper tube, is formulated. The equations that enable one to investigate the kinetics of the stress-strain state of a three-dimensional body have been adapted to operating conditions of the FSAs. A mathematical model of radiation-induced shape change in ferritic-martensitic EP-450 grade steel is proposed. With regard to the proposed model and data on the radiation-induced shape change in other currently used and prospective BN reactor core structural materials, blocks for recording radiation-induced swelling and radiation-induced creep were developed for the ANSYS software package, which made it possible to utilize its potential in this area. The test case with the proposed models of the radiation-induced swelling and creep demonstrates that the developed blocks describe sufficiently well the radiation-induced shape change in the examined structural materials exposed to radiation. Calculation of the radiation-induced shape change in the FSA hexagonal wrapper tube has been performed at various radiation-induced swelling rates and radiation-induced creep moduli. The calculated results and the results of post-irradiation inspection of the FSA dimensions are compared. Recommendations for use of the proposed models designed to calculate and estimate the radiation-induced shape change and define the stress-strain state of the FSAs are made.

The X-ray nondestructive testing process is carried out by a system which includes an object of control (OC), source of radiation, detector, and operator. Under interaction of radiation with the OC, its radiation image is formed as an X-ray dose distribution in accordance with the OC properties. At this stage, useful information about the OC is formed, which is further partially lost, partially distorted, and veiled with a noise by conversion of a radiation image into an optical one. The optical image is analyzed by an operator, and the result of testing depends on his physical and emotional state. In this article, the step-by-step analysis of the entire radiation monitoring system is performed. The first stage is formation of a radiation image. For the theoretical estimate of the minimum defect size detected by the X-ray testing system, spatial-frequency spectrum analysis was used. The minimum sizes of a defect were established, for which the radiation image will be formed depending on the characteristics of the source of radiation and the OC. The second stage is the transformation of the radiation image into an optical one. We presented the simulation of this process and developed a model of how an operator recognizes the X-ray optical image and makes the decision about the OC condition. The optical image formation was studied and the choice criterion for the radiation energy was determined by using the digital radiography technique.