The regularities of joint action of the additives characterized by different inhibition mechanisms for the protection of mild steel in aqueous saline media are investigated. We study, in total, 14 inhibiting mixtures with different concentration ratio. The accumulated results on the protective efficiency and produced morphological and structural modifications of the metal surface are interpreted with

The production of Cu/Ag nano-bimetals for the CO2 reduction on a catalytically active cathode is studied according to the following scheme: the formation of porous copper as a result of selective anodic dezincification of Cu–Zn alloy in an H2SO4 solution and deposition of silver nanostructures by the galvanic replacement. It is shown that the nanosized dendritic formations of silver (70–100 nm) are

We develop a finite-element three-dimensional model of a Bridgman specimen with an aim to investigate its elastoplastic deformation in tension. The distribution of stresses in the cross section of the working part of the specimen for a wide range of loads is determined. It is shown that stresses acting at the center of the specimen in the stage of elastic deformation are lower than the stresses on

We develop a complex technology of fabrication of oil-and-gas pipes with elevated corrosion resistance, including the procedure of controlled forge-rolling of pipe blanks of 06X1-Y steel with regulated contents of chemical elements and the procedure of heat treatment, namely, hardening with double short-term high tempering at temperatures maximally close to the temperature of the α → γ phase transformation

We study the corrosion resistance of an amorphous cobalt-based alloy (AMA) by the method of cyclic voltammetry (VA) in a 1 M KOH aqueous medium at different temperatures varying from 293 to 333°K. It is shown that, as a result of fivefold cyclic polarization of electrodes within the range from – 1.5 to + 0.5 V, the corrosion potential shifts to the cathodic side and, in solutions with temperatures

We established the chemical composition, current efficiency, and corrosion properties of CoW and CoRe binary alloys and CoWRe ternary alloys obtained from electrolytes of two types: citrate and citrate-pyrophosphate. It was discovered that the alloys deposited from citrate electrolyte contain much more refractory metals [51.0 at.% Re and 46.2 (W + Re)] for the same current density of deposition (10

The 2205 duplex stainless steel (DSS) is an alloy containing 22% of Cr and 5% of Ni. The microstructure of steel is a BCC matrix of d-ferrite with FCC islands of g-austenite grains in the 50:50 ratio. DSS is used in the industry due to its high mechanical strength and corrosion resistance that are better than the corresponding characteristics of ferritic or austenitic stainless steels. In the process

We study specific features of the distributions of alloying elements in secondary carbides for the Ni–13.5Cr–5Co–3.4Al–4.8Ti–7.3W–0.8Mo–0.015B–0.12C multicomponent system. The thermodynamic processes of crystallization are modeled by the CALPHAD method. The results of numerical analyses of the chemical composition of carbides are compared with the experimental data obtained with the help of a РЕМ-106І

We study the corrosion behaviors of electrolytic composite coatings based on ternary cobalt alloys under different conditions and analyze the distribution of metals over the thickness of the coating and the parameters of their surface roughness. The accumulated results show that, in alkaline and neutral media, the corrosion potentials shift in the negative direction as compared with the potentials

We study the influence of ultrasonic vibration on the local corrosion and deposition of carbonates onto the surface of AISI 304 stainless steel under the conditions of heat exchange. It is shown that, in the presence of ultrasonic vibration with a power of 9 W and a frequency of 27 kHz, it is possible to shift the activation potential to the anodic side by 0.22 V (from 0.20 up to 0.42 V/SCRE). A mechanism

We present the results of complex investigations of the influence of full cycle of heat treatment (HT) including the procedures of hardening and artificial aging on the corrosion and corrosion-mechanical resistance of welded joints of an aluminum alloy of the Al–Mg–Si–Cu system with a thickness of 1.2 mm. Welded joints were prepared with the use of a nonconsumable electrode by the free arc method in

We analyze the innovative aspects of the formation and development of corrosion protection as an important element of the state engineering and economic policy in the field of quality and safety of industrial objects. A risk-based approach is proposed to overcome the uncertainty of parameters of the corrosion protection of the structures and buildings according to the requirements of the quality function

We solve the plane problem of the theory of elasticity of anisotropic bodies with transverse shear cracks “healed” by the injection technologies, which is reduced to the solution of singular integrodifferential equations for the displacements of crack surfaces. We consider the cases of elastic and viscoelastic fillers of the cracks and evaluate the limit equilibrium state of the bodies with healed

We show the possibility of application of environmentally friendly substances, such as xanthan gum, urotropin, extract of oak chips, and technical glycerol, as corrosion inhibitors for 20 steel, copper, brass, and aluminum in 5% solutions of hydrochloric and citric acids. On the basis of the extract of oak chips, technical glycerol, and urotropin, we create a composition with pronounced synergistic

It is shown that the electrochemical anodic treatment of alloys (stainless steels, Al–Mg alloys, and bronzes) in Ethaline (eutectic mixture of choline chloride and ethylene glycol) can be used as an efficient method for improving not only the surface appearance (to increase gloss and reduce roughness) and some physicomechanical properties (to increase microhardness, wear resistance, etc.) but also

It is shown that xanthan gum inhibits corrosion processes in carbon steel placed in chloride-containing media by the mechanism of adsorption. Potassium-sodium tartrate improves the protective efficiency of xanthan gum. The results of electrochemical impedance spectroscopy confirm the formation of protective barrier layer on steel in a medium inhibited by the composition of gum with tartrate. The Langmuir

We analyze the mechanical, structural-fractographic, and electrochemical methods aimed at the evaluation of the in-service degradation of pipe steels with regard for the corrosion-hydrogen influence of aggressive media. Mechanical methods are used primarily for the evaluation of brittle-fracture resistance. However, in the investigation of forge-rolled steels, it is necessary to take into account the

We establish the influence of the structure of surface layers of aluminum alloy formed as a result of laser modification with silicon carbides on their corrosion-electrochemical behavior in neutral aqueous media. For the laser modification of the surface of 7075 alloy, we use a SiC powder with particle sizes of 80 μm, a hardness of 2600 HV, and a melting point of 2760°С. The SiC powder is blown into

We analyze the corrosion resistance of VT1-0 titanium and VT6 titanium alloy (Ti–6Al–4V) with residual porosities of 1, 3, and 4% obtained as a result of cold pressing and vacuum sintering of titaniumhydride powders in 10, 20, and 30% aqueous solutions of hydrochloric acid. The obtained results are compared with the data on corrosion resistance of the materials produced according to the traditional

We study corrosion, hydrogenation, and mechanical properties of 17G1S-U steel in chloride-acetate solutions with hydrogen-sulfide concentrations of 25, 100, 500, and 1500 mg/dm3. For \( {C}_{{\mathrm{H}}_2\mathrm{S}} \) = 25 and 100 mg/dm3, steel corrodes for 720 h with a rate of about 0.5 g/(m2·h). In these solutions, the yield limit and ultimate strength undergo insignificant changes but the relative

We determine the Gibbs energies for the reactions of interaction of aluminum oxides with neutral or ionized hydrogen in plasma channels in the course of synthesis of oxide-ceramic coatings. It is shown that ionized atomic hydrogen and molecular hydrogen reduce aluminum oxides and decrease the growth rate of oxide-ceramic coatings. We propose new methods for the acceleration of the process of formation

We consider a symmetric problem of harmonic wave loading of an infinite elastic matrix with a oneperiodic array of penny-shaped compliant inclusions. By using the periodic Green function, we reduce this problem to a boundary integral equation for a function characterizing a jump of displacements on one representative inclusion. The Green function used to describe the interaction of inclusions is adapted

We propose a method for the evaluation of the theoretical strength of metal under the conditions of tension and shear. The first of these strengths is determined by comparing the strain energy at the time of fracture with the energy losses required for evaporation. The second strength (obtained on the basis of the data of observations of Luders lines with the help of an electron microscope; × 5000)

We study the influence of ball burnishing on the surface quality, surface hardening, and structure of the surface layers of Ti–6Al–4V (VT6) titanium alloy. It is shown that the degree of surface hardening of the alloy increases with the load applied in the course of deformation treatment. The degree of hardening and the surface quality after treatment are evaluated. The applied procedure of treatment

We propose a mathematical model of production of multilayer filtering porous permeable materials (PPM) with variable porosity by the method of dry radial-isostatic pressing of ShKh15 steel powder together with a pore-forming material. We find the distribution of density along the radius of a hollow PPM obtained by radial-isostatic pressing. On the basis of theoretical calculations, we analyze the factors

We study the influence of electrolyte composition and the parameters of the plasma-electrolytic oxidation of D16Т alloy on the corrosion resistance of synthesized coatings in a 3% NaCl aqueous solution. It was discovered that oxide-ceramic coatings decrease the density of corrosion currents by an order of magnitude as compared with the initial alloy. The lowest corrosion currents were recorded in coatings

We present the results of investigation of the structure and properties of four titanium alloys of the Ti–Nb–Mo system after their subsolidus annealing and annealing with quenching from 870°С. The obtained results indicate that heat treatment strongly affects the phase composition, microstructure, microhardness, Young’s modulus, and elastic properties of investigated specimens. The annealed alloys

We experimentally constructed and computed thermokinetic diagrams of decomposition of supercooled austenite of Ramor-500 and Armox-500 armor steels. The temperatures of phase transformations, microstructure, and mechanical properties of the metal of the heat-affected zone are determined as a result of the simulation of thermal deformation welding at different cooling rates in a Gleeble-3800 installation

We tested cement mortar reinforced with basalt and polypropylene fibers by three-point bending. Possible mechanisms of crack propagation in fibrous concrete are analyzed by the method of acoustic emission (AE). We determine the influence of different volume fractions of basalt and polypropylene fibers on the “load–deflection” curves, ultimate load, deformation, AE-activity, and the parameters of AE

To the article “Enhancement of the Crack Resistance of Si36N4 −Y2O3 Ceramics and Its Structural and Metallurgical Aspects,” by V. D. Vasyliv, O. M. Romaniv, I. V. Zalite, and M. I. Yurkevieh, Vol. 33, No. 3, pp. 323–330, May, 1997

We study the wear resistance of the disks of furrow-openers of seeding machines. The surface nanocrystalline structure of the disks made of 65G steel is formed by the mechanical-pulse treatment under the conditions of dry abrasive friction. It is shown that, in the tests with nonfixed and fixed abrasives, the procedure of surface nanostructuring makes the wear resistance of steel 5.4 and 8.8 times

We construct diagrams of fatigue crack growth for St3ps steel placed in demineralized water and in saturated solutions of the Nurelle D insecticide and UN-32 complex liquid fertilizer and evaluate the corresponding values of threshold and critical stress intensity factors. It is established that, in a Nurelle D solutions, the fatigue crack-growth rate increases, whereas in UN-32 solutions, it decreases

We investigate the corrosion-electrochemical properties of 17G1SU steel in chloride-acetate solutions for different concentrations of hydrogen sulfide. It is shown that, if this concentration increases, then the corrosion potential of steel shifts to the side of more negative values and the corrosion rate increases almost linearly. The presence of hydrogen sulfide does not affect the values of Tafel

We analyze the kinetic features and micromechanism of propagation of fatigue cracks in pseudoelastic nitinol alloy with shape-memory effect under the conditions of constant-amplitude cyclic loading with stress ratios R = 0.2 and 0.5. It is established that, independently of the parameter R, fatigue cracks grow by the quasicleavage mechanism, which is explained by the austenite-martensite deformation

We study the influence of the conditions of impact compaction and heat treatment on the physicomechanical properties and structure of intermetallic compounds. We carried out the procedure of compaction by impact hot pressing of a Fe–14Al (wt.%) intermetallic compound prepared from iron and aluminum powders at temperatures of 1050 and 1150°C, as well as the procedure of annealing of compacted specimens

We study the effect of activation of clinoptilolite specimens by the solutions of HCl, H2SO4 , NaOH, and NH4Cl with their subsequent thermal treatment for the sorption capacity in silver ions. It is shown that the highest sorption capacity is observed for the clinoptilolite activated by a sodium-hydroxide solution. It was established that, in all cases, the increment of sorption capacity observed upon

We study the influence of the conditions of thermochemical treatment (TCT) of annular specimens cut out from a fuel cladding tube made of Zr–1% Nb alloy on their oxidation in air at a temperature T = 550°C for up to τ = 100 h. It is shown that the conditions of TCT in controlled oxygen-containing gas atmospheres decrease the mass increment in the course of oxidation as compared with untreated specimens

We study phase equilibria in a section of 7.14 at.% La in the La–Cu–Si ternary system at 870°K by the methods of X-ray phase diffraction and structural analysis. The existence of two new LaCu9.61Si3.39 and LaCu8.37Si4.63 ternary compounds is established and their crystal structures are studied by the X-ray powder diffraction method. Both compounds are the first representatives of the NaZn13 structural

We study the influence of decrease in the magnesium content and alloying with scandium, zirconium, manganese, and chromium on the structure, phase composition, strength, plasticity, corrosion potential, and corrosion current in alloys of Al−Mg and Al−Mg−Sc systems obtained with the help of a magnetohydrodynamic foundry. The positive influence of lowering of the content of magnesium and replacement

The procedure of gas-metal arc welding (GMAW) has received much attention in recent years and has numerous beneficial applications in the industry, including car industry and ship building. It is expected that the GMAW parameters, such as arc voltage, welding current and welding speed, strongly affect the mechanical properties of welded joints. As one of the most important mechanical properties that

We study the regularities of strain hardening and structural transformations of a tungsten–nickel–iron heavy alloy under the conditions of cold reduction. It is discovered that the alloy with a tungsten content of 89% is hardened easier than the alloy containing 90% W.

We present the results of simulations of the stress-strain state of a traction chain by the finite-element method with regard for the contact interaction and friction between the chain link and the roller. We propose an analytic relation for the approximate evaluation of the fatigue strength of the chain according to the distribution of stresses. We also establish conditions that should be imposed

We study the wear resistance, fatigue strength, and corrosion-fatigue strength of SShKhN-42 rolls made of cast iron with surface nanostructures obtained as a result of mechanical-pulse treatment under the operational conditions of rolls of the rolling mills. It is shown that the surface nanostructure makes the wear resistance of cast iron three times higher and almost doubles the fatigue strength.

A six-component system of CoNiCuCrx high-entropy alloys with different contents of chromium (where x = 0, 0.5, 1.0, 2.0, and 3.0 mole) is obtained by the method of argon-arc melting in a МІFІ-9 study. By the methods of X-ray diffraction analysis, scanning-electron microscopy, and indentation, we investigate the influence of chromium on the crystalline structure, microstructure, and hardness of these

We present the results of investigations of the influence of hydrogen-free carbonitriding in glow discharge on the physicochemical characteristics of the hardened layer of 40Kh steel depending on the content of propane and the pressure of gas atmosphere. We consider three versions of saturation: carbon + nitrogen, nitrogen + carbon, and simultaneous saturation with nitrogen and carbon. The analysis

We study the microstructure of deposited coatings formed by a composite material based on PG-10N-01 self-fluxing alloy and modified with a mechanically activated composite material obtained as a result of the self-propagating high-temperature sintering process. By the X-ray phase diffraction analysis, in the structure of the coating, we detect the presence of titanium diboride (TiB2), nickel boride

We perform the comparative analysis of the corrosion resistance of St3ps steel in demineralized water and in saturated solutions of the Nurelle-D insecticide and UN-32 complex liquid fertilizer. It is shown that, in demineralized water, the general corrosion of the steel surface is predominant. In a solution of insecticide, parallel with general corrosion, we observe a partial realization of pitting

By using the modular-deformation method of calculations, we established the influence of finely divided filler (talc) and additional heat treatment on the elastoplastic properties of polylactide materials. We detected the changes in the modulus of deformation, elasticity modulus, and thermomechanical characteristics of polylactide composites. The maximum values of the moduli and melting point were

By the method of singular integral equations, we solve a plane elastoplastic problem of fracture mechanics for an isotropic plane with an infinite series of curvilinear holes and plasticity bands at their tips. We study the influence of the shapes of smooth holes and the radii of rounding of the contours at their tips on the opening displacements and lengths of the plasticity bands. The solutions of

We develop an electrochemical method aimed at the evaluation of in-service degradation of the mechanical properties of rolled steels of the frames of marine portal cranes. The regularities of decrease in the impact toughness of steels and their polarization resistance are analyzed. The correlation between these parameters forms a basis for the development of a nondestructive method aimed at prediction

The free energy and density of states are computed by the DFT method for the Zr3NiO and Zr3NiN compounds. Their formation was confirmed and numerous Zr3MNx (M = Co, Ni) compounds were synthesized for the first time. It is shown that all these compounds are insertion derivatives of the Re3B structural type (space group Cmcm). We study the process of gas-phase hydrogenation of the obtained subnitrides

We develop a heat-resistant corrosion-resistant alloy based on nickel and alloyed with rhenium and tantalum. This alloy is intended for the production of blades for a new generation of power-generating and ship gas-turbine engines. It is shown that the introduction of rhenium (3.7–4.3 wt.%) and tantalum (2.5–4.3 wt.%) into the composition of the experimental alloy increases the high-temperature corrosion

We study the dependence of the ratio of the cathodic protection current to the ultimate diffusion current for Kh70 steel within the range of protective polarization potentials (-0.75)–(-1.05) V (relative to the silver-chloride reference electrode) standardized by the DSTU 4219 in media with different degrees of corrosiveness. It is shown that, within the рН range 5.6–9.6, as the potential shifts to

We propose a computational model for the evaluation of the service life of fiber-reinforced concrete structural elements subjected to long-term tension. The model is based on the first law of thermodynamics and a proposed idealized tensile stress-strain diagram of fibrous concrete. This model is used for the evaluation of the service life of a fiber-reinforced concrete plate containing a circular hole

We study the problem of contact of two elastic half planes (plane deformation), one of which has a wavy surface under the conditions of partial filling of the interface gaps with compressible liquid. The formulated contact problem is reduced to a singular integral equation for the derivative of the height of the interface gaps and its analytic solution is obtained. We axnalyze the contact behavior

According to the results of simulation of stressed states, it is shown that coarse graphite inclusions formed in the walls of case-shaped parts of transient in thickness are the sites of initiation of defects due to the changes in the dislocation structure and diffusion of carbon from graphite. The cavities formed in graphite also promote the development of oxidation.

The micromechanisms of biocorrosion damage to specimens of 17G1S-U pipe steel are studied on the basis of a combination of the profilometry approaches with fracture mechanics. We develop new methods for the numerical analysis of stress concentration factors regarded as parameters of localization of the microscopic concentrators of corrosion stresses. The improved approach is applied to the analysis

We perform the comparative analysis of the parameters of acoustic structural noise in specimens of 40G structural steel with the use of ultrasonic flaw detectors with phased arrays. It is shown that the parameter of integral density of B-scan images most completely reproduces the variations of energy of acoustic vibrations reflected from the microstructural inhomogeneities (grain-size inhomogeneity

We study a quasicrystalline cast alloy and a film coating obtained by the improved method of threeelectrode ion-plasma sputtering of assembled targets with the following nominal composition: Al60Cu28Fe12 . The structure of the specimens was studied by the methods of quantitative metallography, X-ray diffraction analysis, X-ray energy-dispersive spectrometry, and transmission and scanning electron microscopies

We propose a computational scheme for the evaluation of the maximal temperature of a pad–disk tribosystem in the course of one-time braking with regard for the time of increase in pressure up to its nominal level, the temperature dependence of the characteristics of materials, and the roughness of the friction surfaces. We perform calculations for a three-disk brake made of Termar-ADF carbon composite