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The effect of iron and silicon content on the phase composition, microstructure, hardness, and electrical conductivity of the Al-2% Mn-2% Cu (wt.%) base alloy in the as-cast state and after deformation and heat treatment has been studied. It has been shown that when Fe and Si are introduced together, they mainly bind to the eutectic Al15(Fe, Mn)2Si3 phase. At a cooling rate of ~ 20°C/s the formation of primary Al6(Fe, Mn, Cu) crystals is suppressed if the iron concentration is within 0.4%. Annealing at 400°C of the sheets from as-cast alloys with up to 0.4% Fe and Si leads to A slight softening due to the formation of about ~ 7 wt.% Al20Cu2Mn3 phase nano-dispersoids. The experimental results suggest the possibility of producing new cheap aluminum alloys with high heat resistance without the need for ingots homogenization.

In recent decades, the need to capture carbon dioxide from industrial gas streams, its storage, and utilization has been justified as a rule by environmental problems. However, the capture of CO2 from industrial gas mixtures is an independent important issue of chemical technology. The review addresses consideration and analysis of polymer materials for the membrane separation of CO2-containing mixtures which are of interest for purification of natural gas, biogas, and flue gases and separation of hydrogen from methane and water gas conversion products. Therefore, gas pairs CO2/CH4, CO2/N2, and CO2/H2 are relevant for membrane separation. Promising polymer materials should possess the beneficial combination of CO2 permeability and selectivity for the gas pair of interest, that is, should be located near the upper bound of the Robeson diagram or be above it. For separation of the first two gas pairs good gas-separation parameters are exhibited by rigid-chain highly permeable glassy polymers of various classes (polymers of intrinsic microporosity, polyimides, polynorbornenes, polybenzoxazoles). For separation of the gas pair CO2/N2 the most advantageous properties are shown by polymers bearing functional groups capable of specific interactions with carbon dioxide (aliphatic polyethers and polyimides with their oligomer moieties, polynorbornenes carrying Si‒O–C and Si–O–Si groups, polymers with ionogenic groups). Thermally stable barrier polymers based on polybenzoxazoles show promise for purification of hydrogen from carbon dioxide at high temperatures.

The fluorination of elementary substances and inorganic and organic compounds with elementary fluorine is accompanied by high heat release (of about hundreds of kilojoules per mol of fluorine), which determines the high probability of their implementation in the unsteady-state temperature mode (combustion or thermal explosion mode) when the temperature of the process products is close to adiabatic, and a significant part of the released heat is removed from the obtained substances outside the reaction zone. If target fluorides are present in the thermodynamically equilibrium mixture of substances in an element system that contains fluorine at a temperature close to the adiabatic temperature, fluorination in the combustion mode is successfully used in industry. Otherwise, it is reasonable to perform fluorination in the steady-state (close to isothermal) temperature mode by removing the heat of the reaction from the reacting mixture directly in the reaction zone. This publication considers the efficiency of application of the steady- and unsteady-state temperature modes in the fluorination of various substances with elementary fluorine.

The proposed review represents the systematic analysis of modern methods and approaches for the characterization and structural evaluation of fluorinated polymers that have found a wide application as materials for chemical processing, chemically resistant components and coatings, pharmaceutical and electrical packaging, biomedical equipment, etc. The chemical composition of the polymers (fluorine content, its distribution inside the fluorinated materials, chemical bonds, presence of oxygen-containing groups) substantially influences on the operation properties (chemical resistance, adhesive, cohesive, optical, dielectrical, thermal, barrier, gas permeation) of the final polymeric products. Hence, it was of particularly importanсe to bond the emergence of specific features with the presence of fluorine in the chemical structure of polymer by means of related analytical techniques. Namely, we focused on spectral (IR, UV-VIS, NMR, XPS, EPR), chemical (elemental analysis), Secondary-ion mass spectroscopic (SIMS) and microscopic (AFM, SEM-EDX) methods emphasizing their general consideration and limitations as well as application for the in-depth characterization.

The effect of the annealing temperature on the specific electrical resistance, hardness, and structure of Al–Cu–Mn alloys containing 2 wt % Mn and up to 3 wt % Cu in the as-cast and cold-rolled states has been studied using experimental and computational methods. It has been demonstrated that the best complex of mechanical properties is attained in the cold-rolled sheets containing 2–3 wt % Cu after annealing at 400°C due to the formation of more than 9 vol % of Al20Cu2Mn3 phase dispersoids with an average size of less than 100 nm in their structure. Such a structure provides higher thermal stability in comparison with 1201 grade alloy (of similar alloying system 0.32 Mn, 5.86 Cu, 0.07 Fe, 0.08 Si, 0.08 Zr wt %) hardened by quenching and aging.

An aluminum alloy containing 4% Ca, ~ 1% Fe, ~ 0.6% Si, ~ 0.2% Zr, and ~ 0.1% Sc (wt.%) was manufactured in the form of a 150-mm-diameter × 800-mm-long cylindrical ingot. It is shown that this model alloy has high manufacturability both for the casting of industrial-sized ingots and for rolling or drawing. This is due to the combination of a narrow temperature range of solidification (~ 20°C) and a favorable morphology for the (Al) + Al4Ca + Al10CaFe2 + Al2CaSi2 quaternary eutectic, which has a fine structure and a total content of eutectic phases above 18 vol.%. The high manufacturability of the alloy allows its use for the fabrication of various wrought semi-finished products with a balanced combination of mechanical and physical properties. Compared to other Al-based composite alloys, the Al-Ca alloy has a lower density (2.65 g/cm3), lower cost due to the possibility of using recycled charges (i.e., with higher iron and silicon contents) for their production, and can be further strengthened by L12 type nanoprecipitates.

—This paper examines manufacturability problems of a new Al–Ca–La–Mn alloy in the process of pressure treatment. Electron microscopy and X-ray diffraction analysis were used to perform a detailed study of the structure of the alloy in the cast state and after thermomechanical treatment under different conditions. The cast structure of the alloy is shown to consist of the Al-based solid solution (Al) and Al4(Ca,La) eutectic phase, whose volume fraction is ~15%. The metallographic analysis of the alloys subjected to hot and cold rolling, as well as cold drawing, was performed; a substantial refining of eutectic intermetallics compared to that in the cast state was found. In particular, the homogeneous distribution of submicron spherical particles (300–500 nm in size) in the volume of composite material is observed, which are efficient stabilizers of the structure upon recrystallization. The obtained samples of rolled sheets demonstrate the high thermal stability of the structure and properties during long-term isothermal holding at 250 and 350°С. In particular, it has been shown that the 10-h annealing of cold-rolled sheet 1 mm thick at 250°С leads to a decrease in the hardness only by ~15%. The most favorable conditions for manufacturing the rolled sheets allow us to reach high mechanical properties (an ultimate strength of 240–290 MPa, a yield strength of 200–250 MPa, and a relative elongation of 5.5–15.5%).

Progress in membrane gas separation is impossible without the synthesis of new polymers with improved gas-transport and gas-separation characteristics. The most promising polymeric membrane materials with the advantageous combination of permeability and selectivity, which form the 2008 and 2015 Robeson “upper bounds,” are polyheteroarylenes, among which are ladder polybenzodioxanes, polymers of intrinsic microporosity (PIM), polyimides, polyamides, and polyisathines. Their specific feature is the presence of moieties in the chemical structure that in any way contribute to the loosened packing of polymer chains and the increase in gas-permeability coefficients. Among such macromolecular design elements are groups with main chain kinks or bulky substituents increasing the rotation barriers and rigidity of macrochains. A high gas permeability of the polyheteroarylenes under consideration is commonly combined with an increased selectivity for many gas pairs (e.g., O2/N2, CO2/CH4) primarily associated with a high diffusion selectivity, which suggests their chain packing order and makes it possible to call them polymeric molecular sieves.

The structure of the quaternary Al-(2−4)wt.%Ca-Ni-La system near the aluminum corner has been studied using computational analysis in the Thermo-Calc program and experimental studies (electron microscopy, microprobe analysis and X-ray diffraction). Based on the phase equilibria data obtained, the experimental projection of the liquidus surface and solid state phase-field distribution of the Al-Ca-Ni-La system have been proposed. Microstructure studies reveal that the alloys with the 2-4 wt.% Ca, 2−4 wt.% Ni and 1-3 wt.% La ranges have an ultra-fine hypoeutectic structure with 30% volume fraction of eutectic intermetallics, which allows one to classify these alloys as natural Al-matrix composites. The ultra-fine eutectic structure produces significant strengthening, the magnitude of which can be well described using the modified Orowan looping mechanism model. Small additives of Zr and Sc (0.2 and 0.1 wt.%, respectively) lead to significant strengthening (by ~25%) due to the formation of L12 type phase (Al3(Zr, Sc)) nanoparticles during annealing of the alloy at 350-400 °C. Due to the high volume fraction of eutectic intermetallics, the new alloys have low coefficients of thermal expansion and high thermal stability of the structure and mechanical properties.

Based on the studies of its structure, as well as technological and mechanical properties, the composition and application prospects are substantiated for a high-strength aluminum Al–Zn–Mg–Ca–Fe casting alloy with no heat treatment. As the subjects of study, we have obtained alloys based on a composition of Al–5.5% Zn–1.5% Mg (wt %) jointly and separately alloyed with 0.5–1.0% Ca, and 0.5% Fe. As the reference, we used standard AK12M2, AMg6lch, and AM4.5Kd casting alloys corresponding to GOST (State Standard) 1583–93: by means of pencil sample casting, the alloy has been tested for the tendency to form hot cracks owing to hindered shrinkage. It is shown that separate alloying with calcium and iron does not promote any improvement of crack resistance and adversely affects mechanical properties. The combined alloying with 1% Ca and 0.5% Fe makes it possible to improve the parameter of hot tearing susceptibility to the level inherent in the AMg6lch alloy. This effect is caused by the formation of eutectic calcium-containing phases, and the formation of a favorable grain structure in which there are no columnar grains. Iron in the structure of the alloy is bound in compact particles, representing a Al10CaFe2 phase, which is a consequence of a nonequilibrium crystallization process occurring in the course of chill-mold casting. The formation of this phase makes it possible to reduce the amount of zinc in the (Al, Zn)4Ca phase and mostly to conserve the composition of the (Al) solid solution, as is indicated by similar hardness values of the base Al–5.5% Zn–1.5% Mg alloy and Al–5.5% Zn–1.5% Mg–1% Ca–0.5%–Fe alloy, as well as the superiority of these values over the hardness values of alloys separately alloyed with calcium and iron. In addition, the hardness of the promising alloy in the as-cast state is more than 20 HV higher than the hardness of branded cast alloys in the same condition. The novel alloy in the as-cast state has shown the following competitive mechanical tensile properties: σUTS ~ 310 MPa, σ0.2 ~ 210 MPa, and δ ~ 4%.

The paper substantiates the composition and prospects of using high strength Al–Zn–Mg–Ca–Fe casting aluminum alloy without heat treatment based on the study on the structure, technological and mechanical properties. Alloys of the base composition Al–5.5%Zn–1.5%Mg (wt.%) jointly and separately doped with 0.5–1.0 % Ca and 0.5 % Fe were obtained as the objects of research. Standard casting alloys according to GOST 1583-93: AK12M2, AMg6lch, AM4,5Kd were the objects of comparison. A hot tensile test using a cast test bar was conducted to check the tendency to form hot cracks due to hindered contraction. It was shown that separate alloying with calcium and iron does not contribute to the improvement of crack resistance and adversely affects mechanical properties. Combined alloying with 1 % Ca and 0.5 % Fe improves the hot tearing resistance to the level of the AMg6lch alloy properties. This effect is due to calcium-containing phases of eutectic origin formed and a favorable grain structure created that is free from columnar grains. Iron in the alloy structure is bound in compact Al10CaFe2 phase particles as a result of the non-equilibrium crystallization during permanent mold casting. The formation of this phase allowed to reduce the amount of zinc in the (Al, Zn)4Ca phase and mostly retain the (Al) solid solution composition as evidenced by similar hardness values of the Al–5.5%Zn–1.5%Mg base alloy and Al–5.5%Zn–1.5%Mg–1%Ca–0.5%Fe alloy, and the superiority of the values over the hardness of alloys separately alloyed with calcium and iron. Also the cast hardness of the promising alloy more than 20 HV higher than the cast hardness of commercial cast alloys. The new alloy in the as-cast condition exhibited competitive mechanical tensile properties: UTS ~ 310 MPa, YS ~ 210 MPa, El ~ 4 %.

A comparative analysis of a wire of the Al–7% REM thermostable conductive alloy produced by casting into an electromagnetic crystallizer (EMC) and using the granular technology (RS/PM) method has been carried out. The effect of the annealing temperature (up to 600°C) on the structure of Al–7% REM rods produced using the EMC technology has been studied. Mechanical properties and specific electrical resistivity of the thermostable aluminum wire have been analyzed. It has been shown that the physicomechanical properties of the wire made of the rod cast into an EMC are comparable to those of RS/PM-produced wire.

The phase composition, character of nonequilibrium solidification, structure, and strengthening of alloys based on the Al–8% Zn–3% Mg (wt %) composition, which are cooperatively and separately alloyed with silicon and calcium, are studied in this work using calculations and experimental methods. In the Al–Zn–Mg–Ca–Si system, the (Al,Zn)4Ca, Al2CaSi2, Mg2Si and T (Al2Mg3Zn3) phases can be in equilibrium with the (Al) solid solution. Conditions of the two-stage annealing, which is used for the dissolution of eutectic inclusions of the Т and Mg2Si phases formed upon nonequilibrium solidification, are substantiated. The Al2CaSi2 phase is characterized by needle-like morphology and will not take on a spherical shape upon heating up to 520°С. Upon the individual introduction of silicon (0.5%) and calcium (1 and 2%), the effect of precipitation strengthening upon aging is seen to decrease. This is due to the decrease in the magnesium and zinc concentrations in the (Al) solid solution because of fixing these elements to form the Mg2Si and (Al,Zn)4Ca, phases, respectively. Upon the cooperative introduction of Si and Ca, the Al2CaSi2 phase forms; this allows us, to a considerable extent, to retain unchanged the initial composition of the (Al) solid solution and, therefore, the effect of precipitation strengthening.

A low alloy of the Al–Ca–Fe–Si–Zr–Sc system has been considered in this work. Samples of the alloy have been obtained in some states under conditions that simulate the industrial process of the production of wire. The effect of heat treatment on the electrical conductivity and hardness of the alloy in the form of ingots and sheets has been investigated. It has been shown that the alloy samples with calcium additions in the cold-worked state allow one to obtain a complex of electrical conductivity, strength, and heat resistance comparable to those required by modern standards for cable-conductor semi-finished products. A low alloy of the Al–Fe–Si–Zr system was taken as the object for comparison.

Three poly(arylene ether ketone)s (PAEKs) with propylidene (C1, C2) and phtalide (C3) fragments, and one phtalide-containing polyarylene (C4), were synthesized. Their chemical structures were confirmed via 1H NMR, 13C NMR and 19F NMR spectroscopy. The polymers have shown a high glass transition temperature (&gt, 155 °C), excellent film-forming properties, and a high free volume for this polymer type. The influence of various functional groups in the structure of PAEKs on gas transport parameters was evaluated. Expectedly, due to the higher free volume, the introduction of the hexafluoropropylidene group to PAEK resulted in a higher increase of gas permeability in comparison with the propylidene group. The substitution of the fluorine-containing group on a rigid phtalide moiety (C3) significantly increases the glass transition temperature of the polymer, while the gas permeation slightly decreases. Finally, the removal of two ether groups from the PAEK structure (C4) leads to a rigid polymer chain that is characterized by the highest free volume, gas permeability, and diffusion coefficients among the PAEKs under investigation. Also, theoretically predicted transport parameters were investigated, to further study the structure–properties relationship for the PAEKs. Methods of modified atomic (MAC) and bond (BC) contributions were applied for this purpose (estimation of gas permeation and diffusion). Gas solubility coefficients for PAEKs were forecasted by the “Short polymer chain surface based prediction” (SPCSBP) method. Both the MAC and BC techniques showed reasonable predicted parameters for three polymers, while a significant underestimation of gas transport parameters was observed for C4. The results for all three prediction methods were compared with the experimental data obtained in this work. The predicted parameters were in good agreement with the experimental data for phtalide-containing polymers (C3 and C4), while for propylidene-containing poly(arylene ether ketone)s they were overestimated, due to a possible influence of the propylidene fragment on the indices of the oligomeric chains. MAC and BC methods demonstrated a better prediction power than the SPCSBP method.

The experimental Al-0.6%Zr-0.4%Fe-0.4%Si alloy has been manufactured by using the method of electromagnetic casting. It is shown that Zr is completely dissolved in the aluminum solid solution (Al) and iron is fully included in the Al8Fe2Si phase. The fine microstructure of the as-cast rod implies a high deformation plasticity, which has been experimentally confirmed during wire production. The cold-rolled wire has an ultimate tensile strength (UTS) ~ 260 MPa, and subsequent annealing at 400°C for 3 h slightly reduces the strength, which is associated with the stabilizing effect of the L12 (Al3Zr) phase nanoparticles formed during annealing. Annealing also leads to a significant increase in the specific conductivity, the value of which reaches 57.0 IACS. Drawing of the annealed rolled wire leads to significant strengthening. Annealing at 400°C leads to a marked strength reduction, which, however, remains high enough for conductive alloys (UTS higher than 200 MPa).

Differential scanning calorimetry and differential barothermal analysis demonstrate that a hydrostatic pressure of 100 MPa leads to a shift in the characteristic temperatures of an aluminum-matrix Al–7 wt % Si–7 wt % Cu composite alloy to higher temperatures at pressure coefficients of 0.04–0.12 K/MPa. An increase in the solidus temperature by 6°C, which is most significant from a practical point of view, is shown to enable one to increase the hot isostatic pressing (HIP) temperature as compared to the homogenizing annealing temperature or the heating temperature for quenching. It is also shown that HIP treatment (the temperature of isothermal holding is 515 ± 5°C, the hydrostatic pressure is 100 MPa, the holding time is 3 h) leads to a more compact morphology of Al2Cu and Si eutectic particles in the alloy structure. The results of studying the mechanical properties after HIP treatment and hardening heat treatment according to regime T6 (quenching from 505°C for 1 h + aging at 175°C for 6 h) show that the strength of the alloy increases from 335 to 360 MPa, the relative elongation increases by ~35% (from 2.0 to 2.8%) as compared to a usual specimen, and the reproducibility of the mechanical properties is noticeably improved.

Previously, it was shown that the presence of bulky silicon-containing substituents in the monomer unit of metathesis polynorbornenes hinders the postmodification and, in particular, exhaustive gem-difluorocyclopropanation of main-chain double bonds. In order to reduce the double bonds shielding by substituents, a new polynorbornene with a dimethylsilacyclopentane fragment in the monomer unit, poly(4,4-dimethyltricyclo[5.2.1.02,6]-4-siladec-8-ene) (PNBCP), is synthesized, in which the silylmethyl group is moved further from the double bonds. In order to achieve this, the monomer 4,4-dimethyltricyclo[5.2.1.02,6]-4-siladec-8-ene (NBCP) is first obtained via the diene condensation of 1,3-cyclopentadiene and 1,1-dichlorosilacyclopent-3-ene with following methylation of Si-Cl bonds. NBCP is polymerized by the ring-opening metathesis scheme in the presence of the first-generation Grubbs catalyst, Cl2(PCy3)2Ru=CHPh. The new polymer PNBCP is obtained in a yield of 99–100% and characterized. The gem-difluorocyclopropanation of PNBCP with difluorocarbene, generated during the thermolysis of sodium chlorofluoroacetate, is studied; the conditions for exhaustive replacement of double bonds by gem-difluorocyclopropane are found. It is shown that PNBCP is more active in postmodification compared to poly(5-trimethylsilyl)norbornene but is less active than unsubstituted polynorbornene. It is demonstrated that the introduction of the silacyclopentane fragment into the monomer unit of the metathesis polynorbornene and its subsequent difluorocyclopropanation lead to increase in gas permeability and diffusion and cause a slight decrease in ideal separation selectivities. It is found that gem-difluorocyclopropanation increases the glass transition temperature of PNBCP by 60°C and makes its films stable when stored in air.

Novel polyimides (PIs) based on the isomeric mixture of diethyltoluenediamine and 6FDA, BPDA, BTDA, ODPA, and BPADA dianhydrides are synthesized using a one-stage technique. The synthesized polymers possess high thermal stability and molecular weight, increased glass transition points Tg > 400°C (except for PI with BPADA), and good film-forming properties. The polymers are soluble in chloroform, NMP, DMAA, and DMSO. The investigation of the gas transport of the synthesized polymers shows that the polyimides with 6FDA and BPDA dianhydride fragments can be assigned to the class of highly permeable polyimides (the oxygen permeability coefficients are 82 and 28 Barrer, respectively). The gas transport parameters of the synthesized polymers turn out to be comparableto those for the polyimides based on 2,4,6-trimethyl-m-phenylenediamine studied previously.

The phase equilibria in the Al-Ni-La system and the microstructure and mechanical properties of the alloys with varying La and Ni contents were investigated by using thermodynamic calculations (Thermo-Calc software), electron microscopy, energy dispersive spectrometer and tensile test. It is shown that the microstructure of the most promising alloys with La contents of up to 8 wt% and Ni contents of up to 5 wt% consists of Al primary crystals and ultrafine ternary eutectic (particle thickness is about 30–70 nm) which in turn consist of binary Al3Ni and Al4La compounds. However, at an excessive concentration of La and Ni, the formation of the previously undescribed Al9LaNi2 ternary compound is observed. The actual structure of the ternary diagram is proposed based on experimental data. Uniaxial tensile testing of the promising Al7La4Ni alloy in as-cast state revealed an ultimate tensile strength of about 250 ± 10 MPa, a yield strength of 200 ± 10 MPa and a ductility of 3.0 ± 0.2%.

Differential barothermal analysis (DBA) is used to analyze the effect of hydrostatic pressure of 100 MPa on characteristic temperatures of a number of eutectic alloys (wt %), such as Al–10Si, Al–12Si, Al‒22Cu, Al–33Cu, and Al–7Cu–7Si. According to DBA data, the increase in pressure resulted in an increase in the temperatures of phase transformation; in practice, the most important of them is the nonvariant eutectic transformation temperature that determines the solidus of alloys. It was found that, for the binary systems, the temperatures of the nonvariant eutectic transformation L → (Al) + Si and L → (Al) + Al2Cu increase by 6 and 11°С (from 577 to 583°С and from 548 to 559°С, respectively); for the ternary system, the temperature of transformation L → (Al) +Al2Cu + Si increases by 6°С (from 520 to 526°С). Theoretical analysis, performed using thermodynamic models and Thermo-Calc software, shows that the increase in the eutectic transformation temperature with increasing pressure is directly dependent on the relative decrease in the molar volume of system upon associated eutectic transformation. In this case, the excess dissolution of silicon in (Al) under high pressure can lead to an additional decrease in the molar volume of the system, whereas the increase in the copper solubility is thermodynamically unfavorable.

Polymers with bulky substituents are of pronounced interest in membrane based separation applications. In this direction, the present work reports the synthesis and characterization of a series pendant di-tert-butyl and trifluorometyl groups containing new poly(ether imide)s (PEIs). The PEIs were prepared by thermal imidization of polyamic acid which is derived by the reaction of a diamine monomer, namely 1,4-bis-[{2′-trifluoromethyl 4′-(4″-aminophenyl)phenoxy}] 2,5-di-t-butylbenzene (FMTBDA) with four different commercially available aromatic dianhydrides, i.e. BPADA, 6FDA, ODPA, and BTDA. The PEIs are soluble in many organic solvents and show reasonably high intrinsic viscosity (0.87 to 1.10 dL/g in NMP) and weight average molecular mass as high as 371,900 g/mol with a polydispersity index of 3.8. The proton NMR and FTIR spectroscopic investigation are in accordance with the respective polymer repeating unit structures. The physical properties of the polymers like thermal and mechanical stability are investigated thoroughly to assess their suitability for membrane based application. The polymers are thermally stable up to 474 °C with 10% weight loss temperature in air environment and have a glass transition temperature as high as 253 °C. The polymer membranes have satisfactory mechanical strength with stress at break value up to 95 MPa. The gas permeability coefficients of the PEIs are somewhat higher than those of other polyimides prepared from the same dianhydrides.

This article is devoted to the topical problem of developing antifriction aluminum alloys economically alloyed with low-melting metals. It was found in earlier experiments that an alloy containing about 5% Si, 4% Cu, and 6% Sn (wt %) has a balanced complex of manufacturing and physicomechanical properties. The possibility of decreasing the tin concentration to 4% and its partial substitution by other low-melting metals such as bismuth and lead is considered because of the high cost of tin. The joint and separate influence of these elements on the phase composition of the Al–5% Si–4% Cu–4% Sn alloy is studied using thermodynamic calculations (in the Thermo-Calc program), including the construction of polythermal and isothermal sections. It is shown that additives of lead and bismuth cause the appearance of an extensive area of fluid stratification, so their total concentration should not exceed 1–2%. The phase composition and microstructure of the Al–5% Si–4% Cu–4% Sn–0.5% Pb–0.5% Bi alloy are studied using scanning electron microscopy and X-ray spectral microanalysis. It is revealed that low-melting metals are uniformly distributed in the structure of the alloy in the cast state and, in totality of properties, this material surpasses BrO4Ts4S17 antifriction bronze. Heat treatment according to the T6 mode leads to a significant increase in the hardness of the alloy under study. However, local fusion of the low-melting component occurs during heating for quenching at 500°C, which causes the deterioration of the microstructure during recrystallization and, consequently, causes alloy embrittlement.

By using the experimental study and Thermo-Calc software simulation, the chemical composition of the model alloy containing 1.5% Cu, 1.5% Mn, 0.35% Zr (without the necessity of Sc addition) and with allowable Fe and Si content of up to 0.5% and 0.2%, respectively, have been justified. It was shown that the as-cast structure of the model alloy had the minimum quantity of eutectic inclusions of the Al2Cu and Al15(Fe,Mn)3Si2 phases formed during nonequilibrium solidification, whereas all zirconium content and about 1.1% Mn and 0.8% Cu were dissolved in the aluminium solid solution. Such structure provides high plasticity that allows for the deformation of ingots without their preliminary homogenization. By using the methods of radial-shear rolling (RSR), the 9 mm wire rods were produced from the ingot. The ductility of the rod was sufficient for cold deformation (rolling and drawing) with a high degree of deformation. In particular, a wire with diameters of 1 mm and 0.5 mm, and with UTS value of 430 MPa and 590 MPa, respectively, was obtained by cold drawing. Annealing after drawing reduces the strength properties and improves ductility of the obtained wire. EBSD analysis of the wire after annealing revealed that the described changes in mechanical properties are associated with the formation of a recrystallized grain structure (even in the presence of Zr and Mn-containing dispersoids in a large amount). Thus, using the example of the experimental model alloy, the principal possibility of obtaining a wire with a sufficiently high set of mechanical properties without the necessity of homogenization annealing, solution treatment, and water quenching has been shown.

Results of studies on the separation of gases and vapours using fluorine-containing polymers are integrated and analyzed. Methods for the synthesis of these polymers are considered, including direct gas-phase fluorination, plasma polymerization of fluorine-containing precursors and modification of organic polymers, as well as diverse syntheses of monomers containing C−F and C−CF3 bonds and their subsequent polymerization. Structure – property relationships for these polymers are elucidated and their actual and potential applications as membrane materials are discussed. The bibliography includes 165 references.

The work is devoted to studying the effect of a Sn trace addition on the precipitation hardening after aging of the eutectic Al-7 wt.% Si-7 wt.% Cu alloy. The addition of Sn and Si has a catalytic effect on the precipitation hardening and provides for a significantly higher hardness as compared with the binary Al-Cu alloy. The addition of 0.2 wt.% Sn leads to the formation of a substantially finer precipitation structure compared with the ternary alloy. As a result, the yield strength of the Sn containing alloy is up to 30% higher after uniaxial tensile tests. The finer precipitation structure of the quaternary alloy can be attributed to the higher stabilizing effect of Sn due to its partitioning in the θ″ and θ′ phases. The measured solubility of Sn (about 0.10 at.%) is close to the reported solubility of Si in θ′.

The effect of high-temperature radial-shear rolling (RSR) on the structure formation and mechanical properties of a new high-strength aluminium alloy based on the Al-Zn-Mg-Ni-Fe system was investigated by using transmission electron microscopy, scanning electron microscopy, electron backscatter diffraction, microhardness measurements and tensile test. The processed rod with a diameter of 14 mm was obtained from RSR at 480 °C after four passes with the corresponding elongation ratios: 1.67, 2.78, 5.53 and 8.16 (total value). The microscopic study showed that RSR of the billet led to the formation of a gradient microstructure with a deformed coarse-grained interior and a recrystallized ultrafine-grained surface. The recrystallized structure led to the decrease in microhardness up to 105 HV, whereas the preservation of non-recrystallized structure in the central parts provided an increased microhardness up to 145 HV. The fine crystals of the Al9FeNi eutectic phase and secondary precipitates of the Al3Zr and η(MgZn2) phases provided stability of the formed grain structure due to their high pinning ability. The subsequent analysis revealed that such a combination of structural components provides attractive mechanical properties. In particular, the results of uniaxial tensile tests revealed that the mechanical properties after RSR processing are comparable to the industrial 7075 alloy after equal channel angular pressing for the new alloy with composition Al-7.0% Zn-2.5% Mg-0.6% Ni-0.4% Fe-0.2% Zr (UTS ~ 430 MPa, YS ~ 310 MPa and δ ~ 7%).

Thermodynamic calculations are used to study the phase compositions of Al–Si–X and Al–Cu–X alloys, where X is a low-melting metal (Sn, Pb, Bi, Cd, In). Poly- and isothermal sections are used to determine the temperatures of invariant monotectic reactions. The formation of globular low-melting phase inclusions in heating at 500°C is found by experimental techniques.

Thermo-Calc calculations and experimental methods (optical and electron scanning microscopy, and electron microprobe analysis) were used to study the phase composition of alloys of the Al–Ca–Si–Sc–Zr system with the same scandium and zirconium contents (0.1 and 0.25 wt %, respectively) and the same total silicon and calcium content (6 wt %). It was shown that the hardening due to the precipitation of nanoparticles of the phase Al3(Zr, Sc)–L12 reaches a maximum after annealing at 300–450°C in alloys within the phase region (Al) + Al4Ca + Al2Si2Ca, where (Al) stands for a solid solution based on aluminum. In alloys within this region, almost all of the zirconium and scandium are contained in (Al), and the silicon content of the alloys is minimum. However, Zr and Sc additions have almost no effect on hardening in alloys within the (Al) + (Si) + Al2Si2Ca phase region. The aluminum–calcium eutectic has an essentially finer structure than that of aluminum–silicon.

Though recycling has made advance under immense changes in new techniques, the consumption of primary aluminum remains very high that is mostly advocated by demand of premium wrought alloys, including Al-Zn-Mg, intolerant to Fe and Si impurities of recycling origin. Recently, several works on Al-Ca-Fe-Si alloys showed that calcium may bind the impurities into finely shaped ternary phases Al10CaFe2 and Al2CaSi2. We find it very promising to develop new Al-Zn-Mg-Ca-Fe-Si alloys with a structure containing the foregoing ternary phases instead of Al3Fe and Mg2Si. In this work we studied six compositions based on Al-8%Zn-3%Mg alloy separately and jointly alloyed by 1-2%Ca, 0,5%Fe and 0,5%Si. CALPHAD calculations showed that the alloys may contain up to six intermetallic phases Al4Ca, Mg2Si, A4Ca, Al2CaSi2, Al2Mg3Zn3 and MgZn2 along with (Al). Moreover, the non-equilibrium solidification always ends at approximately 480 oC while the equilibrium solidus is in the 535-560 oC range depending on the alloying content. Having the consistent results on thermal analysis, we proposed the homogenization treatment of cast samples including the first step at 450 oC for dissolving of the non-equilibrium Zn- and Mg-rich eutectic and the second step at 520 oC for tuning the shape of the Ca- and Fe-rich particles up to their spheroidization. Microstructural observations of as-cast samples showed that 1-2%Ca alloying leads to formation of the (Al, Zn)4Ca phase, while the addition of 0.5%Fe and 0.5%Si favors the formation of the Mg2Si and Al8Fe2Si phase. Joint alloying with Ca, Fe and Si brings a far more complicated structure included mostly Ca-rich phases (Al, Zn)4Ca, Al10CaFe2 and Al2CaSi2. The latter has a needle-like morphology, especially coarse at 2%Ca. Hence, after heat treatment the Al-8%Zn-3%Mg-1%Ca-0.5%Fe-0.5%Si alloy showed a better response in spheroidizing of intermetallics. Complex investigation of microstructure of heat-treated samples and hardening showed that the (Al, Zn)4Ca phase brings a decrease in effective Zn content in (Al) and weakening of ageing response (170-180 HV in T6) in comparison to Al-8%Zn-3%Mg (~200 HV in T6). A quite similar result was demonstrated on Al-8%Zn-3%Mg-0.5%Fe-0.5%Si (185 HV in T6) due to formation of insoluble Mg2Si phase along with lowering of the effective Mg solubility. On the contrary, joint alloying with Ca, Fe, and Si provides appropriate strengthening (195 HV in T6) probably due to decrease in amount of (Al, Zn)4Ca and binding of Ca with Fe and Si-bearing phases. In the end we tried out hot and cold rolling (95% total reduction) and showed very good performance of the Al-8%Zn-3%Mg-1%Ca-0.5%Fe-0.5%Si. Though the composition still needs to be tuned, the results show a good promise to progress a currently static research in recyclability of Al-Zn-Mg alloys. Joint alloying with Ca, Fe and Si brings an option in using Fe- and Si-rich aluminum scrap or technically pure primary aluminum.

Al-Mg alloys are normally prone to lose part of their yield and tensile strength at high temperatures due to insufficient thermal stability of the microstructure. Here, we present a Ca-modified Al–Mg–Sc alloy demonstrating high strength at elevated temperatures. The microstructure contains Al4Ca phases distributed as a network along the grain boundary and Al3(Sc,Zr) nano-particles dispersed within the grains. The microstructure evolution and age-hardening analysis indicate that the combination of an Al4Ca network and Sc-rich nano-particles leads to excellent thermal stability even upon aging at 300 °C. The tensile strength of the alloy for temperatures up to 250 °C is significantly improved by an aging treatment and is comparable with the commercial heat-resistant aluminum alloys, i.e., A356 and A319. At a high temperature of 300 °C, the tensile strength is superior to the above-mentioned commercial alloys, even more so when expressed as the specific strength due to the low density of Ca-modified Al–Mg–Sc alloy. The excellent high-temperature strength results from a synergistic effect of solid solution strengthening, grain boundary strengthening and nanoparticle order strengthening.

Fluorine-containing polymers occupy a peculiar niche among conventional polymers due to the unique combination of physicochemical properties. Direct surface fluorination of the polymeric materials is one of the approaches for the introduction of fluorine into the chemical structure that allows one to implement advantages of fluorinated polymers in a thin layer. Current review considers the influence of the surface interaction of the polymeric materials and membranes with elemental fluorine on gas, vapor and liquid transport as well as swelling and related phenomena. The increase in direct fluorination duration and concentration of fluorine in the fluorination mixture is shown to result mostly in a reduction of all penetrants permeability to a different extent, whereas selectivity of the selected gas pairs (He-H2, H2-CH4, He-CH4, CO2-CH4, O2-N2, etc.) increases. Separation parameters for the treated polymeric films approach Robeson’s upper bounds or overcome them. The most promising results were obtained for highly permeable polymer, polytrimethylsilylpropyne (PTMSP). The surface fluorination of rubbers in printing equipment leads to an improved chemical resistance of the materials towards organic solvents, moisturizing solutions and reduce diffusion of plasticizers, photosensitizers and other components of the polymeric blends. The direct fluorination technique can be also considered one of the approaches of fabrication of fuel cell membranes from non-fluorinated polymeric precursors that improves their methanol permeability, proton conductivity and oxidative stability.

Direct fluorination of polymers is a widely utilized technique for chemical modification. Such introduction of fluorine into the chemical structure of polymeric materials leads to laminates with highly fluorinated surface layer. The physicochemical properties of this layer are similar to those of perfluorinated polymers that differ by a unique combination of chemical resistance, weak adhesion, low cohesion, and permittivity, often barrier properties, etc. Surface modification by elemental fluorine allows one to avoid laborious synthesis of perfluoropolymers and impart such properties to industrial polymeric materials. The current review is devoted to a detailed consideration of wetting by water, energy characteristics of surfaces, adhesion, mechanical and electrical properties of the polymers, and composites after the direct fluorination.

Direct fluorination of acetyl- and ethylcelluloses was performed in a bubble reactor with liquid perfluorinated medium (perfluorodecalin). Concentrated fluorination mixtures (F2 + N2) and long reaction times (up to 3 h) were used for better control of the degree of fluorination than it was made previously in direct gaseous fluorination of polymers. The fluorine consumption in the runs with both polymers only slightly increased with increasing temperature and fluorine concentration in the gas mixture. Fluorine content in the fluorinated polymers did not depend strongly on the fluorination conditions. X-ray analysis, differential scanning calorimetry of the fluorinated samples showed no significant changes in respect of the initial polymers. However, emergence of novel and splitting of initial absorption bands, the change of polarization of C–O bonds in IR spectra for the fluorinated samples were observed. It can directly and indirectly justify the appearance of the C–F bonds in the side groups and glycopyranosyl ring of the fluorinated substituted celluloses.19F, 13C solid NMR spectroscopy of the fluorinated samples confirm hydrogen-substituted fluorination of methyl groups.

Questions of the necessity and ways of creating a photometric sensor for the express determination of impurities of light hydrocarbon fractions in wastewater and industrial waters, which are ultimately pollutants of the world's oceans, are posed. The results of studies of luminescence spectra using LEDs as a source of UV stimulation show the possibility of creating a luminescent small-sized highly sensitive sensor for monitoring the presence of light hydrocarbon impurities in wastewater and industrial waters. Achieving greater sensitivity is possible for a real sensor with a specific design.