Ukrainian Journal of Mechanical Engineering And Materials Science. – 2015. – Vol. 1, No. 1

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Науковий журнал

Засновник і видавець Національний університет «Львівська політехніка». Виходить двічі на рік з 2015 року.

Ukrainian Journal of Mechanical Engineering and Materials Science = Український журнал із машинобудування і матеріалознавства : науковий журнал / Lviv Politechnic National University ; editor-in-chief Oleksiy Lanets. – Lviv, 2015. – Volume 1, number 1. – 134 p. : il. – Паралельна назва англійською.

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    Innovation technologies in training specialists in engineering materials science
    (Publishing House of Lviv Polytechnic National University, 2015) Duriagina, Zoya; Bohun, Lidiya; Pleshakov, Eduard; Tepla, Tetiana
    The aim of educational program TEMPUS is the integration of Eastern countries in the Bologna process. Participating of Lviv Polytechnic National University in project “Modernization of two cycles (MA, BA) of competence-based curricula in Material Engineering according to the best experience of Bologna Process – 543994-TEMPUS-1-2013-1-BE-TEMPUS-JPCR” allows to improve the quality of training of specialists in the field of materials science. Directions of “MМATTENG” project realization by Applied Material Science and Materials Engineering chair, implementation of computer-integrated technologies within the project, formation of modernized educational programs, trainings and retrainings of lecturers, seminars on the base of EU Universities, enterprises and companies-developers of software products and formation of the common research centers of materials science with participation of leading foreign and home companies are described in this article.
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    Causes of ductility-dip cracks formation In In52 and In52 MSS alloys during fusion welding
    (Publishing House of Lviv Polytechnic National University, 2015) Beliaiev, Grigorii; Volosatov, Ivan; Kakhovskyi, Mykola
    The aim of the paper is to investigate one of the causes of ductility-dip cracks (DDC) formation. The main aim of this work is calculation of grain boundaries (GB) cohesive energy in nickel based In52 and In52 MSS alloys. For measuring the GB energy anisotropy methods of thermal etching and light interferometry were used. DDC form on the grain boundaries of nickel based alloys due to adsorption of impurities during multipass welding. The In52 alloy has tendency to form DDC during multipass welding fusion unlike In52 MSS one doped with Mo and Nb. The main cause is the change of thermodynamic state of the GB, as it is indicated by the decrease in the cohesive energy to 1.8-1.26 J/m2. During multipass fusion welding in In52 alloy adsorption of S and O from the grains body to GB takes place. The average concentration of O and S on the surface of DDC for high angle boundaries is within 2.3-4.5 and 0.5-1 at. %, respectively. Presented in this paper results have shown the influence of welding heat for reduce the cohesive strength of GB and, as a result, of the formation of DDC. Quantitative effect of S and O as embrittlement elements on the value of decrease in the cohesive energy was shown.
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    Micromechanical properties and thermal annealing of zinc oxide bulk ceramic
    (Publishing House of Lviv Polytechnic National University, 2015) Virt, Ihor; Pavlovskyy, Yuriy; Hadzaman, Ivan
    Zinc oxide has numerous commercial device applications. Polycrystalline ZnO varistors, for example, are widely used in high voltage and power-related applications in industries such as microelectronics. One of the ways to control the properties of ZnO is its annealing in various environments, including oxygen, which leads to increased hardness and fracture toughness of ceramics. Therefore, the study of micromechanical properties of materials for modern electronics is an important and vital issue, both in terms of technology for improving quality of the final product and from the point of view of prospect of its practical use. The structural properties of the ceramic samples of ZnO have been studied. The average grain size has been defined. The micromechanical properties have been studied. The temperature conditions of increasing microhardness of ZnO have been defined after annealing in an oxygen atmosphere.
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    Modification of surfaces of special alloys by nitrogen for power engineering
    (Publishing House of Lviv Polytechnic National University, 2015) Duriagina, Zoya; Tepla, Tetiana
    The use of nitrogen as an alloying element presents a great interest for the improvement of properties of alloyed steels and special alloys. Superficial layers were formed by ionic implantation and by melting the surface by nitrogen plasma. After this kind of treatment, there form a continuous defect-free layers with a good adhesion to the surface. Surface treatment of steels and vanadium alloys increases their corrosion resistance and microhardness of surface layers. A combined supply of alloying elements into the melting area allows us to control the type and the density of secondary phases which are formed as the result of the reaction diffusion. In this way, depending on external needs, it is possible to increase either corrosive-electrochemical properties of the surface (when alloyed layers consist mainly of nitride or oxinitride phases) or wear resistance (when carbide or carbonitride phases will constitute a greater specific volume in the formed layers).
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    The structure, mechanical and electrophysical properties of monocrystalline silicon under influence of constant magnetic field
    (Publishing House of Lviv Polytechnic National University, 2015) Kutzova, Valentina; Nosko, Olha; Sulay, Andrey
    The monocrystalline silicon is one of the most important materials in the view of the fact that it is used in contemporary electronics. The issues concerning silicon processing methods up to now attract a lot of attention of scientists all around the world. From this point of view, the influence of constant magnetic field upon the monocrystalline Czochralski silicon had been studied. The processing of monocrystalline Cz-Si (alloyed with Zr, Hf, Mg, Al, and unalloyed) in weak constant magnetic field (0.07 Tesla) has been carried out. The influence of weak constant magnetic field on the structure, mechanical and electrophysical properties of silicon, namely, increasing of internal defects density, forming of polycrystalline structure in unalloyed silicon, significant increment of microhardness and considerable degradation of minority carriers time of life has been noted. The qualitative explanations of magneto-stimulated phenomena in studied specimens from the viewpoint of spin-conversion as well as changes of electronic states density in the space-time as well as that of the influence of alloying elements on the critical points of first type phase transitions in silicon have been suggested. It has been found that using the weak constant magnetic field lets us to manage the properties of silicon by acceleration or slowing the shear and shear-diffusion phase transitions.