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|Pokhmurskyi V. I., Kalakhan О. S., and Оkhotа H. H. Corrosion electrochemical behaviour of surface modified titanium alloys
SUMMARY. Corrosion-electrochemical properties of titanium pseudo- TC-5 and (+) BT-6 alloys subjected to high-energy (E = 30 keV) ion implantation with nitrogen in the amount of 21017 ion/cm2 and annealing in vacuum at 803 K for 2 h without and with titanium nitride coatings have been studied. The temperature-kinetics method for establishing the limiting stages of corrosion process and anodic dissolution of the modified surfaces in 3% NaCl aqueous solutions within the temperature range of 293…363 K was applied. It has been shown that modification of the surface with nitrogen influences the potential value that corresponds to the start of passivation and the interval of the passive state potentials. It has been found, that the structure of surface films determines the energetics of dissolution process and the value of effective activation energy.
|Shapovalova I. M., Tatarchenko H. O., Zakharov I. I., and Tiupalo M. F. Quantum chemical model of active centres of metals electrochemical corrosion
SUMMARY. A model of active centers formation on the metal surface which determine the behaviour of electrochemical processes has been considered. The quantum-chemical calculations of cluster Sn–Ni8–Ni showed that a tin foreign atom can promote nickel dissolving in acidic medium and in cluster Zn–Ni8–Ni the atom of zinc promotes its passivation. It was also demonstrated that the oxygen added into acid medium promote the nickel passivation.
|Bazeleva N. A. Corrosion electrochemical behaviour of M1 copper in hydroethyleneglycol media
SUMMARY. It has been determined that in aqueous ethylene glycol medium the copper oxidizes to ions Cu+. In the process of corrosion the dissolved oxygen oxidizes ethylene glycol and Cu+ ions to Cu2+ ions, which with ethylene glycol and its oxidation products form complex compounds. Using ion-exchange polishing in cooling system the maximal coefficient of protective action attains 70% and is obtained in the conditions of deep purification of aqueous ethylene glycol heat-carrying agent ( = 100 k m). With the decrease of concentration of dissolved oxygen to 1 g/m3 at minimal depth of purification ( = 5 k m) the coefficient of protective action constitutes 77% and increases to 97% at specific electric resistance of heat-carrying agent, which is equal to 50 k m. The combination of both methods of removing corrosive admixtures (dissolved oxygen, products of copper oxidation and ethylene glycol) essentially raises the corrosion resistance of copper in aqueous ethylene glycol heat-carrying agent.
|Malyshev V. V. and Hab A. I. Galvanic powders and molybdenum coatings and their physico-mechanical properties (A review)
SUMMARY. Electrolytes for galvanic deposition of molybdenum powders and coatings are systematized. Some physico-mechanical properties of coatings are given.
|Fedirko V. M., Matychak Ya. S., Pohreliuk I. M., and Prytula A. O. Description of diffusion saturation of titanium with nonmetallic admixtures regarding their segregation on the surface
SUMMARY. The phenomenological approach to high-temperature interaction between metal and diluted gaseous medium has been developed. The approach is based on the assumption of duplex contact layer existence (with relative thickness 2), where the chemical reactions and gas component migration occur. The non-stationary conditions of mass transfer at the interface are written. They allow to consider a wide spectrum of boundary diffusion phenomena, namely the kinetics of diffusant accumulation near the surface. In terms of the proposed model the kinetics of gaseous saturation of titanium (nitriding and borating) in the diluted medium is proposed. The obtained equations describe the time dependence of surface concentration of gaseous component involving segregation, the specimen mass change owing to both the diffusive impurity solution in metal and the chemical interaction. The role of temperature is also evaluated.
|Solodiak M. T. and Tokarchuk M. V. Electrodiffusion of radionuclei in lava type
SUMMARY. A problem of charged radionuclides transport through the interface between electrolite and lava-like fuel-containing material is formulated and investigated. Electric charge and strength of the electric field are shown to concentrate in the vicinity of the interface and produce the surfacial electric charge. Conditions of minimum electrodiffusion of charged particles are established.
|Duriagina Z. A. and Mudryi S. I. Structural coherence at the interface
of “stainless steel–Li17Pb83 (Pb) melts” system
SUMMARY. It has been shown, that in the thermodynamic open system “stainless steels– Li17Pb83(Pb) melt” the processes of energy and mass exchange take place. Under coherence of the surface atoms and absorbed melt atoms of steel, the dissipative structures (secondary phases) can be formed, proving the ability of nonequilibrium state to serve as a source of ordering. Structural coherence between close order of atoms distribution in Pb, Li17Pb83 melts and the remote order of atoms distribution on the steel surface controls the intensity of interaction in the system “steel–melt”. By changing the structural phase state of steel surface by the methods of surface engineering or by alloying the melt with different elements, it is possible to control the interaction between them at the interface.
|Usov V. V. and Shkatuliak N. M. Fractal nature of brittle facture surface of metals
SUMMARY. The fracture surfaces of the low-alloyed low-pearlite steel after impact bending tests as well as of aluminium wire after fatigue fracture at various temperatures are investigated. It is established that the fracture surfaces after brittle fracture are fractal surfaces. Fractal dimensions of borders of fracture surfaces and the critical sizes of brittle cracks are determined on the basis of the fractal model of the crack. The critical dimensions of brittle cracks are found too.
|Balytskyi O. I., Kolesnikov V. O., and Kubitskyi E. Improvement of crack growth resistance of manganese cast irons
SUMMARY. The parameters of static (K1С = 30...44 МPа ) and cyclic crack growth resistance of austenitic manganece cast-iron (ΔKth = 4,7 ... 6,3 МPа , ΔKfc = 35 ... 44 МPа ) were established. The obtained results are compared with literature data. The high K1С values in alloys were attained thanks to refining action of calcium. The fracture mikromechanism of these materials obtained, using the modern methods of investigations is studied. It is shown, that parameters of graphite phase, and also toughness and plasticity of metallic matrix have a considerable influence on the fracture resistance.
|Musii R. S. and Stasiuk H. B. Equation of dynamic thermoelasticity problem in stresses in triorthogonal coordinate system
SUMMARY. The initial system of determining equations in stresses of the dynamical thermoelasticity problem in the triorthogonal coordinate system has been written using the equations of motion, Hooke’s law, Cauchy’s correlation and Saint-Venant’s compatibility conditions. This system has been reduced to the system of successive connected wave equations; the equation for the first invariant of stress tensor being independent. The initial conditions for the key functions have been written.
|Pauk V. and Zastrau B. Rolling contact of a cylinder with wavy surface|
|Yevtushenko O., Semerak V., and Yevtushenko Ol. Approximate calculation
of temperature for the “wheel–rail” tribosystem
SUMMARY. An approximate solution of two-dimensional quasistatic heat conductivity problem for a semispace, heated on the surface by a rapid moving distributed heat flux has been constructed in terms of piecewise-linear approximation methods and a Green’s function. It has been assumed that the obtained solution under certain conditions models the heat formation, due to wheel-rail friction. The conducted numerical analysis showed that the minimum temperature on the contact area does not exceed 450C even at great (2%) slip coefficient and is too low for the beginning of martensitic transformations in steel.
|INVESTIGATION AND TEST METHODS|
Kolodii B. I. and Seniuk M. M. Possibility of checking the adhesive connection of bodies by their sounding with a plane transverse electric wave
SUMMARY. The coefficient of a plane TE-wave reflection from the adhesive joint of a plate and a semi infinite body containing intermediate layer has been analytically determined, the dependence of permeability over the layers thickness being linear. By analyzing the quantitative frequency dependences of reflection coefficient on the investigated objects the conclusion about the possibility of detection of the intermediate layer and its thickness by comparing the theoretical and experimental sounding data by waves of 3…5mm range was done.
|Shyrokov V. V., Arendar L. A., Kovalchyk Yu. I., Vasyliv Kh. B., and Vasyliv O. M. Computer processing of frictional surface profilograms
SUMMARY. The kinetics of the change of profile microrelief parameters is the main characteristic of the friction surface. The program Roughness Plot Analyzer has been created for precise calculation and analysis of profile parameters. The program allows to analyze the friction surface relief change depending on wear conditions and material properties, what is important for establishing wear mechanizms.
|Ivanytskyi Ya. L. and Shtaiura S. T.Determination of crack growth resistance characteristics under mixed mode fracture macromechanisms
SUMMARY. A method for static crack growth resistance testing of materials under mixed mode fracture (I + II) (tear and transverse shear) and (I + III) (tear and longitudinal shear). Cylindrical specimens with a circular crack and an edge eut were subjected to testing under both tension and twisting (Fig. 1). The specimens were described, the methods of testing, determination of the force and deformation characteristics of crack growth resistance for given loading conditions were determined, the results were processed as crack resistance curves (Fig. 3 and 4). The methodical instructions have been developed, using the requirements and regulations of the national standards [9–11].
|SCIENCE FOR PRODUCTION |
Narivskyi O. E. Corrosion fracture of lamellar heat-exchangers
SUMMARY. In heat-transfer plates, independent of steel grade, the pittings arise mainly at the tips of corrugations and in the places of minimum clearance between the adjacent plates. The pitting initiation sites are nonmetallic inclusions of complex oxides (Al, Si, Ti and Mg) and oxy-sulphides (Ti and Ca). It has been experimentally proved that heat-transfer plate deformation has almost no effect on corrosion losses under testing in chloride containing environment. Depassivation and pitting development occur near the nonmetallic inclusions of a specific nature. In chloride-containing environments the pittings arise near oxides and oxy-sulphide nonmetallic inclusions, while in chloride-containing environments with oxidizers – at the oxy-sulphide and nitride inclusions.
|Radkevych O. I., Chumalo H. V., Yurkevych R. M., Vasylyk A. V., and Antoshchak I. M. Investigation of serviceability of pump-compressor pipes made of group K steels
SUMMARY. The resistance of steel of strength group К to corrosion, corrosion-hydrogen and corrosion-mechanical fracture in hydrogen sulfide-containing environments of Lokachi gas-field and NACE solution has been analyzed. It has been shown that this steel is not inclined to hydrogen induced cracking (HIC), resistance to sulfide stress corrosion cracking is ssc 0.80.2min , while the corrosion rate is much lower than the dangerous threshold value. Thus, it is possible to prove, that tubing and casing columns of this steel can be used safely on Lokachi gas field.
|Kostornov A. G., Moliar A. G., Nenakhov A. V., and Nechyporenko O. Yu. Antifriction materials based on polytetrafluoroethelene for pipeline articulated joints
SUMMARY. The influence of nature and volumetric content of fillers on the antifrictional characteristics of the fluoroplastic is investigated. It has been established, that fluoroplastic filled with fine powders of molybdenum disulphide and graphite provides highly effective work in pair with ПТ-7М titanium alloy under dry friction.
|SHORT REPORTS |
Tokovyi Yu. V. and Rychahivskyi A. V. Analytical solution of the plane thermoelasticity problem for an inhomogeneous strip
|IN SCIENTIFIC CIRCLES |
Nykyforchyn H. М. Stress corrosion cracking of high-strength steel pipelines
|Rytsar B. and Mykulchyk R. Advances of the Ukrainian scientific and technical terminology|
|Stashchuk M. H.Problems of brittle fracture mechanics|
|Vasyliv Kh. B. Theoretical and applied tribology|
|Okhota H. H. Corrosion theory and corrosion protection|