AbstractCopper electrodeposited composite coatings containing two types of aluminum-oxide powders with different dispersities (alumina Al2O3-1 and electroexplosive aluminum-oxide nanopowder Al2O3-2) are obtained during the work. The studies show that introducing the powders leads to a change in the microstructure of the composites and a change in the grain growth principles during the formation of the coatings. Refinement and ordering of the grain structure of the coatings occurs and twinning defects and texture are formed. The change in the formation of the microstructure of the composites leads to a change in some operational characteristics: an increase in the microhardness (by 10% in the composites with the addition of alumina and by more than 30% in the coatings with electroexplosive aluminum oxide) and ultimate tensile strength (by 20% in the composites with Al2O3-1 and almost 1.5-fold in the samples with Al2O3-2).

AbstractIn the present study, chitosan coatings modified with g-C3N4 were prepared for AZ91 magnesium alloy. The microstructure of the chitosan–g-C3N4 coatings, depending on the concentration of the particles of the modifying phase in the chitosan solution, was investigated by scanning electron microscopy and X-ray phase analysis. It was found that coatings prepared in suspension of chitosan containing more than 30 g/dm3 g-C3N4 exhibited a complete wettability with a sodium-phosphate buffer solution. Confocal microscopy established the degree of inhibition of E. coli biofilm formation on the surface of the prepared coatings. It was found by using linear voltammetry and electrochemical impedance spectroscopy that the modification of chitosan by the g-C3N4 particles led to an improvement in the protective properties of coatings.

AbstractThermally stimulated processes in mixtures of boric acid (BA) with boron nitride (BN) and aluminum that underwent the plastic deformation under a pressure of 0.5–4.0 GPa in an anvil-type high-pressure apparatus were studied with differential-scanning calorimetry, thermogravimetry, and mass spectrometry. Water releases in initial BA within 20–200°C, which leads to an endothermic effect. The weight loss associated with release of water in the deformed BA–BN mixture proceeded within 20–200 and 250–450°С according to mass spectrometric data. The enthalpy of water release endoprocess within 200–200°С decreased with an increase in an amount of BN in mixtures and with an increase in deformation pressure, and it remained constant within 250–450°С. There were endopeaks on the thermogram of the BA–Al starting mixture due to the release of water and an endopeak of aluminum melting. The thermograms of the deformed mixtures showed an exopeak of aluminum melting and an exopeak within 200–550°C.

AbstractThe study described the synthesis and spectral characterization of four novel enolimine ligands; 1-(((2-hydroxy-5-methylphenyl)imino)methyl)naphthalene-2-ol(L1), N-((2-hydroxynaphthalen-1-yl)methylene)pyrazinen-2-carboxamide(L2), 1-((thiazol-2-ylimino)methyl)naphthalene-2-ol(L3) and 1-(((3-methylpyridin-2-yl)imino)methyl)naphthalene-2-ol(L4) by solubility; melting point and elemental (CHNS) evaluations; proton and carbon nuclear magnetic resonance, electronic (UV–Vis) and vibrational (IR), spectrophotometry. The ligands were investigated for corrosion inhibition potentials. The solubility data revealed that all the organic ligands were soluble in dimethylformamide ((CH3)2SO) but insoluble with water (OH2). The IR spectra of the ligands presented bands at 1631–1685 cm–1 indicative of imine functional group and corroborative of enol assemblage. The effect of the ligands on acid corrosion of mild steel (ms) confirmed substantial corrosion inhibition behaviour as against corrosion of ms in one mole of hydrochloric acid solution. The weight loss (WL) shows that the heterocyclic organic inhibitors had excellent corrosion inhibition performance at high temperature. The highest inhibition efficiency of 90% was observed at 3 h for both L3 and L4, and 89.20% for L3 at 5-h immersion in the acid solution at 308 K temperature, and 500 ppm concentration. Substantial chemical calculations were also accomplished at B3LYP level with 6-31G (d, p) basis set and molecular descriptors which include dipole moment (μ), energy gap, EHOMO, and ELUMO were used. Koopman’s theorem was used to derive and analyze the global reactivity descriptors; global softness (S), global hardness (η), electrophilicity index (ω). The organic ligands were found to be in good agreement with both experimental and theoretical results.

AbstractThis paper studies the kinetics of adsorption of lead ions from aqueous solutions under static conditions on a new nanocomposite material—graphene oxide/lignosulfonate (GO/LS). The adsorption capacity of the nanocomposite with respect to lead ions was 179 mg/g at a extraction time of 20 min. The experimental kinetic dependences were processed in the coordinates of the Elovich pseudo-first- and -second-order models, as well as the Morris and Weber diffusion models and the Boyd model. The performed calculations led to the conclusion that the pseudo-second-order model most accurately describes the adsorption of Pb2+ ions on GO/LS (R2 = 0.999). In this case, the calculated adsorption capacity was 182.52 mg/g. According to diffusion models, sorption is not limited by diffusion, but the rate of the process is limited by diffusion through the film formed on the surface of the sorbent. Thus, we can conclude that the film-diffusion mechanism of adsorption of Pb2+ ions on GO/LS with a contribution to the overall rate of the process of sorbate–sorbate interaction. The results obtained allow us to state that the GO/LS nanocomposite is a promising sorbent in the processes of removing heavy-metal ions from polluted hydrogeosystems and can be considered an effective solution for ensuring the environmental safety of the environment.

AbstractIn recent years, surface mechanical attrition treatment (SMAT) operations have drawn the researchers attention in terms of the impact of this operation on wear resistance, hardness and creation of residual stresses. In this study, the effect of SMAT operation time on microstructure, residual stress, hardness and wear resistance was investigated. For this purpose, the specimens were subjected to SMAT at three times of 10, 15 and 20 min and compared with the As-received specimen (specimen without SMAT). XRD has been used to measure grain size and residual stress, SEM to check the microstructure, the hardness, wear resistance and roughness of the specimens were also measured. The results showed that the grain size decreases due to SMAT operation, so that the grain size decreasees from 139.2 nm in the As-received specimen to 93.2, 72.6 and 34.9 nm in the SMAT specimens with times of 10, 15 and 20 minutes, respectively. Also, residual stress is created due to compressive force and microstrain as a result of SMAT operation, which is 158, 170 and 234 MPa for 10, 15 and 20 min SMAT specimens, respectively. As a result of SMAT operation, the hardness and wear resistance of the specimens increase, which is due to the fact that the fine grains, nanocrystalline of their grains and many microstrains created. Studies have shown that hardness and wear resistance increase by 36, 45, 62% and 16, 27, 36% at SMAT times of 10, 15 and 20 min, respectively, compared to the As-received specimen. Examination of the wear mechanism indicates that the wear mechanism in the As-received specimen is strong adhesive and tribochemical wear, which in SMAT specimens decreases due to the increase in hardness of the adhesive wear. Also, by performing SMAT operation, the specimen roughness increases.

AbstractN,N'-Bis(3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-oxalamide (NNB) was synthesized via a non-solvent reaction mechanism. NNB was characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1HNMR) spectroscopy. Inhibition of corrosion in carbon steel was studied in the presence and absence of NNB in 1 M HCl solution using standard gravimetric technique and potentiodynamic polarization at 303–323 K. This was further subjected to quantum chemical parameters using density functional theory (DFT). FTIR and 1HNMR results confirmed the synthesis of NNB. The inhibition of carbon steel corrosion by NNB obeyed Langmuir isotherm at an efficiency of 78.10%. Lowest unoccupied molecular orbital (LUMO) as well as the highest occupied molecular orbital (HOMO) revealed insight into the interaction between NNB and the corroded carbon steel. The free energy of adsorption (\(\Delta G_{{{\text{ads}}}}^{^\circ }\)) increased as the temperature increased while the enthalpy (\(\Delta H_{{{\text{ads}}}}^{^\circ }\) ) revealed the inhibition process to be exothermic.

AbstractParticles with an aluminum core and a hydroxide shell obtained by low-temperature (up to 100°C) oxidation of spherical aluminum micron particles with water are studied. Processes occurring upon heating these particles up to 750°C in a controlled gaseous atmosphere are analyzed. The composition and amount of released gas-phase products are studied, and their nature is determined. The transformation of the shell as a result of the phase transition of aluminum hydroxide to oxide is considered. The mechanism of formation of cracks as a result of thermal expansion of the core and shell during the heating of the particle is considered. Outcrops of aluminum onto the surface of the oxide shell after reaching the melting point of aluminum are noted. It is proposed to use aluminum extruded onto the surface for the formation of bonds between the particles upon executing 3D printing.

Abstract—The work is devoted to the study of the properties and selection of the optimal method for applying an intermediate coating on steel, which serves as an adhesive support layer for extremely hard CVD coatings. In this work, a study of the structure and properties of multilayer coatings of the Ni–P and W–C systems was carried out. The morphology, phase and elemental composition of the layers obtained have been studied by scanning electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. It is shown that nickel coatings consist mainly of a metallic phase, despite the high phosphorus content in the Ni-P layers. Mechanical tests of the coatings showed that the support layer obtained by the method of electroless plating tends to increase in hardness, and tests for adhesion strength showed some advantage of electroless nickel plating over electroplating, providing a higher resistance to destructive effects during testing.

Abstract—Ti and carbon steel are the materials most commonly employed in numerous industries. Nevertheless, adverse hardness, wear and corrosion resistance restrict numerous applications. We combined two surface processes technologies, thermal spraying and MAO, to produce a TiO2/Ti/Fe composite material. Firstly, a titanium (Ti) layer was prepared by thermal spraying on AISI 1020 carbon steel, and then additives in varying amounts were added to the electrolyte of micro-arc oxidation (MAO) to improve the wear and corrosion resistance. MAO current density and voltages were set at 35 A/dm2 and 450 V, the operation time of MAO was 10 min. The concentration of graphene added to the electrolytes were 0, 0.01, 0.03, 0.05, 0.07, 0.09 g L–1, and indicated as TiO2/Ti-F, TiO2/Ti-G1, TiO2/Ti-G3, TiO2/Ti-G5, TiO2/Ti-G7, TiO2/Ti-G9, respectively. Subsequently, surface roughness, thickness, microstructure, hardness, crystal structure, and composition were measured to confirm the properties of the oxide layer. Then the results of corrosion and wear tests to measure the wear and corrosion resistance of the oxide layer. As the results indicated, the specimen containing graphene (TiO2/Ti-G) has higher hardness, lower surface roughness, and about twice the thickness of oxide layer than the specimen without graphene (TiO2/Ti-F). In corrosion resistance, TiO2/Ti-G was at least about 30% more improved than TiO2/Ti-F, and TiO2/Ti-G7 was about 5 times better. In wear resistance, TiO2/Ti-G was at least 47% more improved than TiO2/Ti-F, and TiO2/Ti-G7 was about 80% better.

AbstractThe degree of extraction of silver and copper from solutions of their salts by atomic hydrogen in Pd was studied, as well as the conditions for their most complete extraction. The Ag+ concentration was 12.67 and 0.635 g/L, and that of Cu2+ was 1.145 and 1.527 g/L. The residence time of Pd in solution was 1 h. Electrochemical hydrogenation of Pd was carried out in 1 M NaOH solution at 30 mA/cm2 for 9 min until completely saturated with hydrogen, at which H : Pd was 0.73. It has been established that the PdH system has the ability to efficiently extract silver (and copper) with 100% yield if the amount of hydrogen in Pd exceeds the amount of Ag in solution. The main conditions for this are solutions diluted with silver (with respect to copper) and a large working surface of Pd samples. It has been established that the chemical deposition of silver on PdH is accompanied by the formation of colloidal silver near the surface, which can be isolated from the solution. The main condition for this is a low hydrogen content in the sample (Н : Pd < 0.3). The result of this is a decrease in the rate of hydrogen diffusion to the sample–solution interface, and the lifetime of the colloid increases.

AbstractThe effect of the hardening conditions and the nature of the filler and the organic modifier on the physical and mechanical properties of coatings based on a cycloaliphatic epoxy matrix filled with muscovite mica and TiO2 has been studied. The dependence of the values of hardness and the wetting angle on the amount of polyetheramine hardener (20–50 wt %) has been presented. The effect of the nature of the hardener and additives of ground granite and SiO2 microspheres on the values of hardness, adhesion, and impact and bending strengths of the epoxy coating has been studied. Four optimal compositions of epoxy coatings for the study of thermal stability and anticorrosive properties have been determined. It has been shown that coatings containing oligoethoxysiloxanes as organic modifiers are characterized by low degree of corrosion protection.

AbstractA study was made of a thermal interface based on a two-dimensional allotropic modification of carbon (graphene), presented in the form of a powder, for cooling integrated circuits. Such physical properties of the thermal interface as thermal conductivity, heat capacity, thermal diffusivity, and density are determined by the empirical method. The process of heat transfer in the most efficient thermal interface sample during the operation of integrated circuits in the ANSYS engineering analysis system is presented. The prospects of using pressed graphene powder as a thermal interface in order to eliminate the use of a binder are described. The paper also makes a comparison with the most effective type of thermal interfaces currently in use.

AbstractCorrosion resistance of structural materials has become one of the most important aspects in the electronics industry. In particular, biodeterioration and biocorrosion lead to operational failures and high economic losses. Biocorrosion of copper and base materials applied for the production of printed circuit boards is studied in this work. The inevitable change in the properties and destruction of textolite and glass textolite that are used in the composition of radioelectronic components and are in contact with copper often results in violations of the performance of devices and equipment. An attempt to explain the role of biofilms of microfungi as the main factor of mycological corrosion of copper in the composition of some electronic-industry products is made in this work.

Abstract—Both traditional stone-like and novel microspheric ZnNiAl-layered double hydroxides (LDHs) were used as adsorbents for methyl orange removal from water. The stone-like ZnNiAl-LDH was synthesized by a coprecipitation method (c-LDH), and the microspheric ZnNiAl-LDH was prepared by a hydrothermal method (h-LDH). The special surface area of h-LDH (188.8 m2/g) is higher than that of c-LDH (71.0 m2/g), then h-LDH shows an excellent adsorption performance than c-LDH. The Al3+ content in microspheric ZnNiAl-LDH also has an impact on the adsorption capacity, which enhances with the Al3+ content increasing. The adsorption kinetics can be described with the pseudo-second-ordered model for both LDHs, and the adsorption isotherms of h-LDH can be fitted well by the Langmuir model, while the Freundlich model is better fit for c-LDH. The adsorption mechanisms for both LDHs are mainly attributed to ion exchange, electrostatic interaction and accompanied by surface complexation simultaneously.

AbstractIn the present study, polycaprolactone fumarate (PCLF) and polycaprolactone fumarate/silicon and magnesium codoped fluorapatite nanoparticles (PCLF/Si–Mg–FA nanocomposite) were deposited on the surface of Ti–6Al–4V alloy via dip-coating technique. The adhesion test, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS), X-ray diffraction (XRD) technique, Fourier transform infrared spectroscopy (FTIR), electrochemical, and in vitro biocompatibility evaluations were utilized to characterize coated and uncoated specimens. The results show that uniform nanocomposite coating (thickness of about 6.65 µm) with appropriate adhesion strength and a homogeneous distribution of Si-Mg-FA nanoparticles throughout the PCLF matrix was coated on the substrate. The potentiodynamic polarization and electrochemical impedance tests, in agreement with each other, indicated higher corrosion resistance of nanocomposite coating in comparison to uncoated and PCLF-coated specimens. Cell cytotoxicity (MTT) evaluation and cell adhesion examinations show no toxicity and represent a good cell attachment with flattened sheet morphologies for nanocomposite coating.

Abstract—Electroless Ni–W–P–nSiO2 coating is successfully deposited on L245 carbon steel by electroless plating technique. The results of X-ray diffraction (XRD) and transmission electron microscope (TEM) show that coating is hybrid structure of amorphous and nanocrystalline. Differential scanning calorimetry (DSC) results indicate that the amorphous structure of coating starts to transform into crystalline structure at approximately 400°C with activation energy of 306.5 kJ/mol. Crystallization reaction rate is KT = 4.11 × 1020exp(–306.5 kJ/RT). In order to further research the change of coating structure and property during crystallization, heat treatment tests at 300, 350, 400, 450 and 500°C are carried out in chamber electric furnace (SX-4-13). During heat treatment process, the phase composition of different stages can be summarized as: amorphous phase + Ni nanocrystalline (300°C) → amorphous phase + aggregated nanocrystalline (350°C) → remaining amorphous phase + aggregated nanocrystalline + new Ni3P phase (400°C)→Ni crystalline phase + growing Ni3P phase (450°C) → growing Ni crystalline phase + growing Ni3P phase (500°C). The coating has the best corrosion resistance after 350 °C heat treatment.

AbstractThe microstructure, phase composition, and resistance to oxidation upon heating in air in the temperature range of 600–1100°С for composites synthesized in the gasless combustion mode of reactive powder mixtures of titanium, aluminum, and silicon have been studied. Silicide Ti5Si3 and titanium trialuminide TiAl3 were synthesized from two-component mixtures. The combustion products of ternary mixtures contain Ti5Si3 and TiAl3, the ratio of which depends on the aluminum content in the reaction mixtures. The scale resistance of the synthesized powder composites is determined to a greater extent by the microstructure of the granules than by their phase composition. The composition was determined of the reaction powder mixture, the combustion products of which have a scale resistance 1.5–3 times higher than the combustion products of the other studied compositions.

AbstractComposite electrochemical coatings based on a tin–nickel alloy with a composite of the “SiO2 core–TiO2 shell” type have been obtained. Corrosion properties of coatings were studied in 3% sodium chloride solution. Biocidal properties of coatings with respect to Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 strains were studied. It was found that, to impart biocidal properties to the surface, the minimum concentration of composite in the electrolyte should be 4 g/L.

AbstractZn-Al-Mg alloys with the alloying elements of Si, Ti and Zr by microalloying method were designed. The microstructure was well characterized, and the Rockwell hardness as well as anti-corrosion were tested. The results showed that the alloys with Si, Ti and Zr elements not only contain the same Al rich phase, Zn rich phase and lamellar Zn/Al/MgZn2 ternary eutectic structure as Zn–5Al–2Mg, but also the formation of Si rich phase, Ti(Al1 – xSix)3 phase, Al3Zr phase and Al3(Ti, Zr) phase, respectively. The electrochemical test demonstrated that Zn–5Al–2Mg–0.2(TiZr) alloy has higher corrosion resistance as compared to that with the addition of (Si,Ti) and (Si,Zr) elements. Therefore, the addition of Ti and Zr elements can greatly improve the corrosion resistance of Zn–5Al–2Mg alloy. Moreover, the corrosion products of Zn–5Al–2Mg alloy and Zn–5Al–2Mg–0.2(TiZr) alloy were tested by XPS. The results showed that the addition of Ti and Zr inhibits the formation of loose porous ZnO, while promotes the formation of compact Zn5(CO3)2(OH)6, Zn5(CO3)2(OH)6 can adhere to the sample surface well, hinder the charge transfer, and improve the corrosion resistance of the alloy.