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The paper studies the structure and microhardness of the heat-affected zone, welding area in low carbon and low alloy steel 09G2S (AISI A516 grade 55), and the coating created by two-pass manual metal arc welding with the addition of titanium carbonitride nanoparticles. It is shown that the microhardness dependence on the distance to the coating surface is divided into four zones. The microstructure of each zone is studied by using the optical and scanning tunneling microscopies. It is found that the formation of highly dispersed acicular ferrite and globular bainite structures in the deposition superheat zone of surfacing is favorable for the improvement of the coating–base metal composition impact toughness.

ETVS fuel assemblies containing nitride fuel rods with different structural implementation and cladding made of different materials are tested in the cores of the BN-600 and BOR-60 reactors in order to substantiate the efficiency of fuel rods with mixed uranium-plutonium nitride fuel used in sodium-cooled (BN-1200) and lead-cooled (BREST-OD-300) reactors. We report here the results of post-reactor studies of BN-600, -800, -1200 and BREST type fuel elements with a helium sublayer after irradiation to maximum burnup 7.5, 6, and 4.5% h.a., respectively, in the composition of 10 ETVS BN-600 fuel assemblies as well BREST type fuel rods with helium and lead sublayer after tests to maximum burnup 5 and 4% h.a. as fuel elements of the BREST type with a helium and lead sublayer after testing to maximum burnup 5 and 4% h.a. in the composition of two ETVS BOR-60 fuel assemblies. The obtained results confirmed that the nitride fuel rods with gas and lead sublayers and EP-823 steel cladding remain efficient at the attained test parameters and, possibly, at higher fuel burnup.

Experimental fuel rods with mixed uranium-plutonium nitride fuel are being tested in the BOR-60 reactor as part of collapsible irradiation devices, which are prototypes of fuel rods of the BREST-OD-300 reactor being designed. Currently, reactor tests of fuel rods with a helium sublayer as part of OU-2, as well as lead alloyed with components of EP823-Sh steel as part of OU-4, are continuing. In 2018, one fuel rod was removed from OU-2 and one OU-4 after the first stage of reactor tests with the rods replaced by others from those previously irradiated and post-reactor studies were performed. Information on the features of the radiation swelling of the uranium-plutonium nitride fuel of these fuel rods is presented.

The paper deals with a comparative study of equilibrium and kinetics of phenol adsorption from aqueous solutions by means of commercial activated carbons and semi-cokes, differing in the nature of feedstock, production technology and structural characteristics. The main adsorption parameters are calculated with the usage of Langmuir and Dubinin–Radushkevich equations. The change in the characteristics of the structure and state of the surface of semi-coke P2 as a result of modification is estimated. It was found that phenol adsorption kinetics is described by a pseudo-second-order model. The adsorption rate constants and the coefficient of external diffusion mass transfer are calculated. It is proved that phenol extraction from aqueous solutions presents a mixed-diffusion nature, and the process rate is limited by external mass transfer for 13 min for SKD-515 and 22 min for ABG. To increase the adsorption capacity, the oxidative modification of the semi-coke P2 was carried out. Considering the economic and technological aspects, ABG semi-coke is recognized as a promising sorbent for phenol extraction from aqueous media.

В работе рассматривается способ термокомпенсации узкополосных фильтров на поверхностных акустических волнах (ПАВ), отличающийся от известных тем, что функция термокомпенсации происходит в кристалле посредством обратного пьезоэффекта, воздействием на него управляющими встречно-штыревыми преобразователями (УВШП), сформированными на обратной стороне подложки, то есть в одной среде с функцией фильтрации. Физически, термокомпенсация происходит за счет изменения упругости подложки, а, следовательно, изменением скорости акустического сигнала в достаточном диапазоне температур для практического применения.

We studied trichloroethylene (TCE) adsorption from aqueous solutions in equilibrium conditions by activated carbons (AC). They differ in raw materials, porous structure characteristics and chemical state of the surface. TCE adsorption isotherms were found to have a concave shape, which is characteristic of a sorbent—sorbate weak interaction. It can be a result from electrostatic repulsion of organic matter molecule from polar groups on carbon surface and adsorbed water molecules. The basic parameters of adsorption were calculated by the Dubinin–Radushkevich equation. We determined that for AG-OV-1 and SKD-515 in the coordinates of the Dubinin–Radushkevich equation, there are two linear plots suggesting adsorption in pores of different sizes or reorientation of adsorbate molecules on the activated carbon surface. The efficiency of TCE removal by the activated carbons was evaluated. To reduce the TCE to the maximum allowable, the lowest sorbent consumption was observed for AC with the highest values of surface area and micropore volume. However, the high cost and hydrophobicity of these adsorbents make it impractical to use them in adsorption columns with a fixed layer. We offered an adsorbent that reasonably combines extraction efficiency, ease of operation and economic feasibility.

Electron-microscopic and electron-probe x-ray spectral studies of nitride fuel microstructure in thin sections and fractures of pellets in correlation with the xenon distribution were conducted in order to obtain data on the particulars of porosity formation and mechanisms of swelling of nitride fuel during low-temperature irradiation. The results attest indications of restructuring of nitride fuel irradiated to burn up 5.5% h.a. at temperature below 880°C. The formation of some grain structure in the restructuring process, accompanied by emission of gaseous fission products from the fuel matrix into pores, affects the swelling rate of uranium-plutonium nitride fuel.

Scanning tunnel microscopy is used to directly estimate the relative energy of internal interfaces in ultrafine-grained copper after equal-channel angular pressing, followed by rolling. Estimates of the boundary energy for as-prepared samples and samples annealed at different temperatures indicate that ultrafinegrained copper has nonequilibrium boundaries with energy higher than that in coarse-grained copper. The cumulative distribution functions of the relative boundary energy in the grain–subgrain structure allow the qualitative estimation of the redistribution of excess energy between the boundaries of various types during structure evolution upon annealing. Differences between the behaviors of the cumulative distribution functions of relative boundary energy in ultrafine-grained copper and nickel produced by the same technology are revealed. These differences are related to the characteristics of the structure formation of two metals during severe plastic deformation and its subsequent evolution during annealing, which depend on the stacking fault energy and the melting point of copper and nickel.

The structure and microhardness of the heat-affected zone of low-carbon and low-alloy steel 09G2S, the melting zone and the coating obtained by manual electric arc welding using electrodes modified with nanoparticles of titanium carbonitrides have been investigated. It is shown that the dependence of microhardness on the distance from the coating surface has 4 stages. The microstructure of all zones has been studied using optical and scanning tunneling microscopes and its effect on the impact strength of the coating-substrate composition is discussed.

The dependence of the apparent density of oligomethylsiloxane–filler systems on the size of the microspheres and their bulk density was established. The acid–base method was used to determine the acid–base properties of the surface of fillers and to assess the interaction at the phase boundary.

Today an application of metal nanoparticles as additives to base oils is widely studied in tribological centers in many countries. The additives containing nanoparticles essentially raise the wear resistance ability of lubricants and reduce the friction coefficient. However, such lubricants are still not widely used. This paper gives a brief analysis of the problem.

A carbosilane pseudo-dendrimer with irregular structure and degree of branching DB = 1 was synthesized and fractionated. The molar masses of the obtained fractions ranged from 5000 to 490 000 g mol−1. The hydrodynamic and conformational properties were studied by the methods of light scattering, sedimentation-diffusion analysis and viscometry in dilute hexane and toluene solutions. The Mark − Kuhn − Houwink dependences were obtained. The results for the pseudo-dendrimer are compared with the data for the initial hyperbranched poly(diallylcarbosilane) with DB = 0.5 and carbosilane dendrimer. It is shown that the solution properties of the pseudo-dendrimer are close to those for the irregular hyperbranched polymer and differ significantly from the dendrimer behavior. Hence, it is branching regularity rather than the degree of branching that determines the conformational and hydrodynamic properties of hyperbranched polymers with a high degree of branching DB ≥ 0.5. © 2014 Society of Chemical Industry

Comblike block copolymer having a polyimide backbone and poly(N,N-dimethylaminoethyl methacrylate) side chains, i.e., PI-g-PDMAEMA, was prepared through the “grafting from” method using (N,N-dimethylaminoethyl methacrylate) polymerization on a polyimide multicenter macroinitiator by atom transfer radical polymerization (ATRP) mechanism. Its molar mass characteristics were determined in chloroform solution using hydrodynamic methods. PI-g-PDMAEMA is a relatively loose molecular brush with the substitution degree z = 0.44. The behavior of PI-g-PDMAEMA in aqueous solutions at a concentration 0.015 g cm−3 was studied by light scattering within a pH interval from 2.1 to 12.4. The temperature dependences of light scattering intensity and hydrodynamic sizes of dissolved species were obtained. Synthesized copolymer shows clearly temperature and pH responsiveness. PI-g-PDMAEMA is thermo-sensitive at pH ≥ 8.9. The pH growth is accompanied by a decrease in the phase transition temperature and an increase in the width of the phase transition interval and hydrodynamic radii of the micellar aggregates and large loose aggregates.

The effect of solvent quality with respect to main and side chains on the conformations of molecular brushes is investigated by the methods of molecular hydrodynamics and optics as well as by computer simulation. Copolymers with a polyimide backbone and poly(methyl methacrylate) side chains are studied in solvents featuring strongly different thermodynamic qualities (chloroform, ethyl acetate, and 3-heptanone). The studied samples have close total molecular masses and backbone lengths but differ in grafting densities and lengths of side chains: a brush with densely grafted and relatively short side chains versus a brush with loosely grafted but very long side chains. For both types of brushes, similar changes in hydrodynamic behavior with improvement in the solvent quality are found experimentally. Computer simulation shows that these changes have different origins. In the former case, macromolecules are elongated, and their volumes grow simultaneously, while in the latter case, the shape of the macromolecules remains close to spherical and the changes in hydrodynamic parameters are mainly due to an increase in the volume of macromolecules.

Graft copolymers with a polyimide backbone and poly(methyl methacrylate) side chains are investigated in dilute chloroform and ethyl acetate solutions via the methods of molecular hydrodynamics and optics. Copolymer samples are prepared through the “grafting from” method via atom-transfer radical polymerization with a multicenter polyimide macroinitiator. In solutions of copolymers with low degrees of functionalization Z (40%), supermolecular structures are formed as a result of interactions between the polyimide backbones. In samples with Z → 100%, the backbone is well screened by side chains; therefore, molecular solutions are formed in both solvents. The hydrodynamic and conformational behavior of samples with high functionalization degrees changes after the transition from ethyl acetate to chloroform owing to the different thermodynamic qualities of the solvents with respect to the copolymer components. In both solvents, the backbone tends to avoid contact with a poor solvent. This effect is more pronounced in the case of ethyl acetate. Macromolecules of the studied graft copolymers are characterized by high equilibrium rigidities (>40 nm) that are 10 times higher than the corresponding characteristics of aromatic polyimides.

A series of novel metal–organic frameworks comprised of Zn–O–Zn dinuclear units and multidentate pyridine-2,5-dicarboxylate linkers were synthesized under mild conditions. The crystal structure and composition of the novel phases were established from synchrotron powder diffraction data. Small variations in the parameters of the synthesis led to formation of the metal–organic systems of different topologies, either 3D metal–organic frameworks (MOFs) or a 0D molecular complex. The novel MOFs feature a permanent porosity. The excess hydrogen uptake measured for the selected MOF sample was about 0.9 wt % at 77 K and 1 bar. Structural examinations indicated the phase transformation in several samples caused by the absorption of the atmospheric water molecules. The thermal stability and guest-molecule content in the pores of the novel MOFs were also characterized by TGA-DSC.

In the article presented are the results of post-irradiation tests of helium bonded fuel pins with mixed mononitride fuel (U 0.55 Pu 0.45 )N and (U 0.4 Pu 0.6 )N having 85% density irradiated in BOR-60 reactor. Achieved maximum burn-up was, respectively, equal to 9.4 and 12.1 at.% with max linear heat rates 41.9 and 54.5 kW/m. Maximum irradiation dose was 43 dpa. No damage of claddings made of ChS-68 steel (20% cold worked) was observed, and ductility margin existed. Maximum depth of cladding corrosion was within 15 μm. Swelling rates of (U 0.4 Pu 0.6 )N and (U 0.55 Pu 0.45 )N were, respectively, ∼1.1% and ∼0.68% per 1 at.%. Gas release rate did not exceed 19.3% and 19%. Pattern of porosity distribution in the fuel influenced fuel swelling and gas release rates.

The main domestic and foreign results obtained in the course of reactor tests and post-reactor studies of alloyed fuel are reviewed. The regularities of its radiation swelling and mechanical and chemical interaction with fuel-element cladding are determined. The knowledge accumulated about the properties and behavior under irradiation of alloyed metal fuel can be helpful in designing a fuel element that is serviceable to burnup ≥20% h.a.

The principal results from studies of the state of fuel elements with nitride fuel for subsequent work on use in fast reactors are reviewed. It is shown that fuel elements with nitride fuel and helium filler can secure serviceability to burnup, determined by the onset of kernel–cladding interaction. Nitride fuel in fuel elements with a liquid-metal contact layer is a promising variant for attaining deep burnup.

The results of post-reactor studies of U0.55Pu0.45N and U0.4Pu0.6N mixed mononitride fuel elements (density 85% of the theoretical value) and a helium sublayer are presented. The fuel elements are irradiated in a BOR-60 reactor to burnup 9.4 and 12.1% h.a., respectively, with power density 430 and 540 W/cm. All fuel elements remained hermetic; the ChS-68 steel cladding (20% cold deformation) retained excess plasticity. The maximum zone of interaction between the cladding and the fuel and fission products did not exceed 15 μm. The swelling rate of U0.4Pu0.6N and U0.55Pu0.45N fuel was 1.1 and 0.68%/% burnup, respectively. The gas release did not exceed 19.3 and 19%. The steel damage dose was 43 dpa. The character of the porosity distribution in the fuel affects the swelling and gas release.

Experimental data on the permittivity of water and steam depending on the ratio of the density to temperature have been generalized. The relations obtained allow one to calculate the vapor content of two-phase states in application to thermal-power plants.

Hyperbranched polycarbosilanes are investigated by the methods of molecular hydrodynamics and optics. Dependences of the hydrodynamic and conformational properties of these polymers on their molecular mass, the length of linear chains between branching points, and the chemical structure of end groups are analyzed. The hydrodynamic behavior of hyperbranched polycarbosilanes is explained by the fact that the dimensions of their macromolecules are compact and their shape is close to spherical. The convolution of chains between branching points becomes more pronounced with an increase in their length and a decrease in the molecular mass of the polymer. When end fluorinated groups are incorporated into the hyperbranched polycarbosilane, in thermodynamically good solvents and θ solvents, hydrodynamic characteristics change apparently owing to a change in the density of macromolecules in solution. In a poor solvent, the compaction of fluorinated macromolecules and a reduction in their shape asymmetry are observed. At a fixed branching degree, the hydrodynamic properties of hyperbranched polymers depend on the structural regularity of their macromolecules: In terms of hydrodynamic properties, the hyperbranched polycarbosilane with a degree of branching of 1 and a random distribution of branching points within the volume of a macro-molecule is appreciably different from a dendrimer of the same chemical nature and is close to polycarbosilanes with a degree of branching of 0.5.

Foundation slabs and other massive reinforced concrete structures in the process of their construction experience temperature effects as a result of heat release during concrete hardening. In combination with variable environmental conditions there is an uneven distribution of temperatures in the massive structures thickness, which can cause cracks in the process of concrete strengthening. The heat of concrete is mainly influenced by several factors: the cement specific content, type of cement, water-cement ratio etc. Numerical methods provide the most complete way to estimate thermally stressed state of structures. This paper suggests method of 3-D temperature field calculation for temperature regime estimation of the most typical cast in place reinforced concrete structures (foundation slabs). The influence of sample size, ambient temperature and thermal insulation parameters of the samples outer faces was studied. The program for the ANSYS is developed, which allows estimating the temperature regime of reinforced concrete structures at the early stages of concrete hardening. © Published under licence by IOP Publishing Ltd.

By means of a numerical experiment with the example of methane, we analyze the features of the working process of a reciprocating expander with heat release associated with condensation, friction, and external heat exchange. The influence of the technical characteristics of expanders and inlet gas parameters is also considered.

Cylindrical dendrimers of first, second, and third generations with side dendrons based on L-aspartic acid which are attached to poly(styrenesulfonic acid) chains via ionic bonds are studied by molecular hydrodynamic, optical, and electrooptical measurements. Macromolecules of the said dendrimers demonstrate significant kinetic rigidity in external electric and hydrodynamic fields simultaneously with moderate equilibrium chain rigidity. The comparative analysis of the experimental data on various cylindrical dendrimers with the polyvinyl backbone and L-aspartic acid-based dendrons is performed. It has been shown that, in solvents not disturbing intramolecular hydrogen bonds between side dendrons, the conformational and dynamic properties of various cylindrical dendrimers are similar. The molecular characteristics of cylindrical dendrimers in non-dissociating solvents are insignificantly affected by the mode of dendron attachment to the backbone (covalent or ionic binding).

A model of gas cooling and condensation in a piston expansion machine has been developed with allowance made for formation of nuclei of the liquid phase and growth of droplets as well as for real thermophysical properties. Internal heat release related to phase transition is taken into account in the adiabatic equation. The processes of cooling and liquefaction of methane in the piston expander are calculated for specific conditions.

The paper presents the results of studying alloyed metal fuel after irradiation in a fast reactor. Determined is the mechanism of fuel irradiation swelling, mechanical interaction between fuel and cladding, and distribution of fission products. Experience gained in fuel properties and behavior under irradiation as well as in irradiation-induced thermal effects occurred in alloyed metal fuel provides for a fuel pin design to have a burnup not less than 20% h. a.

Revue des differents types de refractaires utilisables: magnesie, oxyde de calcium, dolomie, corindon, zircone, spinelles…

The working efficiency of vacuum-induction furnaces largely depends on the operational resistance of the refractory linings. The authors examine linings for large-tonnage vacuum-induction furnaces of the ISV-25 at the Chelyabinsk metallurgical combine. The design of the ISV-25 furnace specifies three modifications of inductor in which crucibles of capacity 6, 12.5, and 25 tons are prepared. A study was also made of the chemical composition and physicoceramic properties of refractories Magnel, Korundal KhD, and Koral BP. Use was made of methods of chemical, petrographic, spectral and x-ray phase analysis. The data obtained are presented. Using thermodynamic data, it is possible to calculate the reaction of carbon dissolved in the metal with the refractory oxides MgO, Al/sub 2/O/sub 3/, ZrO/sub 2/, SiO/sub 2/, and CaO, which are most often used as lining material for vacuum-induction furnaces.

The method of lining the ISV-25 furnace crucible with individual parts is illustrated and includes working and insulated layers divided by sheet asbestos. Imported Magnel refractories or domestic PKhP fused periclase-chromite refractories are used to prepare the working layer of the crucible. the insulation layer is made of Coral BP or MKS-83 mullite-corundum parts and the collar is lined with Alusa or ShA-35 chamotte parts. In order to compare the wear of domestic and imported refractories used under identical conditions and to establish the degree of interaction of the metal with PKhP parts a combined lining of Magnel refractories and fused PKhP periclase-chromite parts was installed. After successful testing of the combined linings it was desirable to line the crucibles of large-tonnage vacuum induction furnaces with PKhP fused periclase-chromite refractories with the use of MMKhPV mortar.