Browsing by Author "Rusnac, Vladislav"

Now showing 1 - 19 of 19
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    Analiza morfologiei suprafeţelor pentru emisie electronică obţinute în urma prelucrării cu aplicarea descărcărilor electrice în impuls [Articol]
    (USARB, 2014) Topală, Pavel; Rusnac, Vladislav; Guzgan, Dorin
    The formation of cone shape asperities on the work-piece surface by applying electrical discharges in impulse (EDI) leads directly to increasing its active area. Currently this phenomenon can be successfully used to manufacture cathodes that are used in electron beam equipment fulfilling the function of concentration of thermal and electrical fields in the active zones of cathodes in the process of electronic emission. The work-piece surface has a special micro-geometry that facilitates the increase of electronic emission comparatively with the same pieces unprocessed by this method.
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    Cercetarea rezistenţei la uzură a straturilor superficiale obţinute la alierea prin scîntei electrice în cîmp magnetic [Articol]
    (USARB, 2008) Pereteatcu, Pavel; Beşliu, Vitalie; Rusnac, Vladislav; Balanici, Alexandru; Ojegov, Alexandr; Mihailov, Valentin
    În lucrare sînt prezentate rezultatele încercărilor tribologice a straturilor superficiale obţinute la acţiunea cîmpului magnetic asupra procesului de aliere prin scîntei electrice (ASE). Cercetările experimentale efectuate au demonstrat că acoperirile obţinute în condiţiile ASE cu suprapunerea cîmpului magnetic, se uzează mai puţin faţă de aceleaşi acoperiri depuse prin procedeul ASE tradiţional.
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    Cercetări experimentale privind modificarea geometriei suprafeţelor pieselor metalice [Articol]
    (USARB, 2014) Topală, Pavel; Guzgan, Dorin; Rusnac, Vladislav
    The results of experimental investigations related to processing plane and cylindrical metal surface by electrical discharges in impulse (EDI) method are presented in this paper. It was established that some asperities named cones Taylor are formed on the work-piece surface as a result of its interaction with plasma canal. The appearance of these cones is possible at certain energetic temperature of the processing.
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    Cercetări experimentale privind modificarea microgeometriei suprafeţelor pieselor metalice privind metoda electroeroziunii [Articol]
    (USARB, 2008) Rusnac, Vladislav
    În lucrare sunt prezentate rezultatele cercetărilor experimentale privind formarea meniscurilor sub formă de conuri Taylor pe suprafeţele pieselor cu aplicarea descărcărilor electrice în impuls. Se examinează influenţa energiei acumulate pe bateria de condensatoare şi a duratei impulsului asupra formării acestora. Modificarea microgeometriei suprafeţelor pieselor are ca scop sporirea capacităţilor de absorbţie a radiaţiei şi de emisie a particulelor elementare. Se demonstrează că dimensiunile meniscurilor formate sunt funcţie de regimul energetic de prelucrare, mărimea interstiţiului, durata descărcării electrice în impuls şi propriităţile termo-fizice a materialului de execuţie al piesei.
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    Cercetări experimentale privind obţinerea peliculelor de oxizi pe suprafeţele semiconductoare cu aplicarea plasmei [Articol]
    (USARB, 2015) Topală, Pavel; Rusnac, Vladislav; Guzgan, Dorin; Ojegov, Alexandr
    The paper presents the results of experimental investigations aimed at the formation of thin oxide films on semiconductor surfaces by plasma applying. The morphology of obtained films depending on the electrode base material is examined. A special interest presents clusters formed on the semiconductor surfaces after processing, which highlights new properties that differ from the properties of the separate molecules and of the base material.
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    Cercetări experimentale privind prelucrarea complexă a oţelurilor cu un conţinut de carbon < 0,35% [Articol]
    (USARB, 2022) Pereteatcu, Pavel; Ojegov, Alexandr; Cracan, Cornel; Ţîganaş, Ion; Rusnac, Vladislav
    The paper presents some results of the complex processing of metal surfaces made of steel with a carbon content ≤ 0.35%. The complex processing was performed in different consecutiveness: ESA + CHTT and CHTT + ESA. Electrodes – anodes for ESA were made of Chromium and Aluminum. The obtained results demonstrated the effectiveness of such processing, which finally leads to the improvement of some physical-mechanical characteristics of the metal surfaces.
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    Ciclul de lucrări de laborator la disciplina "Metrologie, standardizare şi controlul calităţii"
    (USARB, 2012) Rusnac, Vladislav; Burlacu, Dumitru
    Lucrarea "Ciclu de lucrări de laborator la disciplina "Metrologie, standardizare şi controlul alităţii"" prezintă un astfel de îndrumar pentru disciplina menţionată în titlu, care este inclusă în programul de studiu a studenţilor la specializarea „Educaţie Tehnologică". Lucrarea începe cu o introducere care argumentează necesitatea studierii acestei discipline. Ulterior sunt descrise obiectivele generale ale disciplinei şi procesul de realizare a lucrărilor de laborator. Procesul respectiv conţine trei etape: de pregătire, de execuţie şi de susţinere şi fiecare din ele este descrisă detaliat pe paşi, deoarece studenţii în majoritatea cazurilor se pregătesc independent pentru fiecare etapă.
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    Distribuţia temperaturii în piesa de lucru la aplicarea descărcărilor electrice în impuls [Articol]
    (USARB, 2008) Rusnac, Vladislav
    În lucrare sunt precăutaţi factorii principali ai căldurii, generate de descărcările electrice în impuls. Se prezintă distribuţia temperaturii în piesa de lucru, demonstrîndu-se că acesteia îi revine un rol esenţial în procesele de prelucrare dimensională, formare a straturilor de depunere şi de modificare a microgeometriei suprafeţelor pieselor metalice.
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    Eficienţa aplicării instrumentelor de calitate pentru asigurarea creşterii economice [Articol]
    (USARB, 2018) Rusnac, Vladislav; Ursu, Mădălina
    This article proposes clear examples of quality improvement in economic using „7 tools of quality‖ [Q7] and „7 modern tools of management‖ [M7], their definitions and a presentation of their usefulness and of course their differences. A theoretical introduction demonstrates what these tools real represent following directly with examples, diagrams, graphics, pictures and pointing their advantages and disadvantages. The focal point of the paper consists in approaching the feat concept of using these tools in analyzing and solving the errors and in coordinating the continual efforts of the process of tools improvement in economic. The implementation of these tools of quality are based on a suitable planning and focused on new ideas in promoting a long-term effectiveness and satisfaction of customers.
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    Experimental investigations concerning the extraction of cone meniscus on metal surfaces with Electrical Discharge Machining (EDM) adhibition [Articol]
    (USARB, 2008) Topală, Pavel; Rusnac, Vladislav
    The paper presents the results of experimental investigation concerning cone meniscus formation on innard surfaces with impulse discharge adhibition. The aim of surface micro geometry modification is to increase their absorption capacity of radiation and the emission of elementary particles. It is shown that the size of the formed meniscus depends on the energy processing regime, device size, electric discharge in impulse duration and thermo - physic properties of executive innard material.
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    Formarea micro- şi nano-structurilor pe suprafeţe metalice în condiţii descărcărilor electrice [Articol]
    (USARB, 2023) Ojegov, Alexandr; Beşliu, Vitalie; Topală, Pavel; Hîrbu, Arefa; Rusnac, Vladislav
    The paper is dedicated to theoretical-experimental research on the formation of micro- and nano-structures on metallic surfaces under conditions of pulsed electric discharge machining (PEDM). In the case of the processing of construction steels with the graphite tool-electrode by applying PEDM in maintenance regime of the „cold” electrode spots, the formation of graphite structures (of the fullerene and single-walled carbon nanotube type) of the nanometric order was detected. Due to the superior mechanical properties, the coatings with micro- and nano-dimensional layers of carbon on the metal base can be applied to the processing of machine building parts in order to increase the wear resistance of the active surfaces.
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    Formation of Taylor Cone Shaped Asperities on Cylindrical Surfaces by Applying Electric Discharges in Pulse [Articol]
    (USARB, 2014) Topală, Pavel; Rusnac, Vladislav; Guzgan, Dorin
    This paper presents the results of experimental research on Taylor cone shaped meniscuses formation on the surfaces of pieces by applying electric discharges in pulse. It examines the influence of energy stored in the capacitor and of pulse duration on their formation. The modification of piece surface micro-geometry aims to increase the capacity of absorption of radiation and of particle emission. It shows that the size of formed meniscuses depends on the energy regime of machining, on the gap size, on the duration of electric discharges in pulse and on thermal-physical properties of the material used to execute the piece.
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    Modificarea structurală a compoziţiei chimice şi a microgeometriei suprafeţelor pieselor cu aplicarea descărcărilor electrice în impuls [Articol]
    (USARB, 2011) Topală, Pavel; Beşliu, Vitalie; Rusnac, Vladislav; Ojegov, Alexandr; Pînzaru, Natalia
    Lucrarea de faţă prezintă noi tehnologii de prelucrare şi anume durificarea cu electrizi-scule din grafit, depunerea peliculelor de grafit, creşterea meniscurilor toate acestea realizîndu-se prin aplicarea descărcărilor electrice în impuls, în regim de subexcitare cu impulsuri monopolare şi bipolare. Aceste noi tehnologii ne permit marire durabilităţii pieselor supuse prelucrării în condiţii de producere, permit podificareea microgeometriei suprafeţelor prelucrate, sporesc esenţial emisia termoelectronică ale acestora circa de 9 ori.
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    Noi secvenţe la tabloul fizic al fenomenului electroeroziunii [Articol]
    (USARB, 2005) Topală, Pavel; Olaru, Ion; Rusnac, Vladislav
    In this work is proposed a new model of analyzing the physical portrait of the process of electric erosion in normal conditions. Based on analysis of the bibliographic sources of nowadays and based on the result of the personal researches, the authors propose a model, based on capillary waves appearing and tneir developing on surface of the electric field.
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    Obtaining surfaces with taylor cone shaped asperities of micro- and nano-scale dimensions using the EDI method [Abstract]
    (USARB, 2014) Topală, Pavel; Beşliu, Vitalie; Rusnac, Vladislav; Guzgan, Dorin; Pleşco, Irina
    The present paper is devoted to experimental investigations concerning the treatment of conductive surfaces by applying electric discharges in impulse (EDI). We have particularly focused on the modifications of metal surface micro-geometry leading to the formation of Taylor cone shaped asperities. We have established and presented the best energetic regimes of extracting the latter from cylindrical and flat pieces made of W+10%Re using EDI.
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    Obtaining Surfaces with Taylor Cone Shaped Asperities of Micro-and Nano-Scale Dimensions Using the EDI Method [Articol]
    (ModTech Publishing House, 2014) Topală, Pavel; Beşliu, Vitalie; Rusnac, Vladislav; Guzgan, Dorin; Pleşco, Irina
    Nowadays the stage of technical progress is characterized by a transit from macro to micro and nano scale dimensions. The present paper is devoted to experimental investigations concerning the treatment of conductive surfaces by applying electric discharges in impulse (EDI). We have particularly focused on the modifications of metal surface micro-geometry leading to the formation of Taylor cone shaped asperities. We have established and presented the best energetic regimes of extracting the latter from cylindrical and flat pieces made of W+10%Re using EDI.
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    Oxidation of Taylor cone-shaped asperities by application of plasma in normal condition [Articol]
    (USARB, 2015) Topală, Pavel; Ojegov, Alexandr; Beşliu, Vitalie; Rusnac, Vladislav; Guzgan, Dorin; Hîrbu, Arefa; Pleşco, Irina
    This paper refers on experimental investigations of the conductive surface treatment by applying electric discharges in impulse. We have particularly focused on the modifications of metal surface micro-geometry that leads to formation of Taylor cone shaped asperities. We have established and presented the best energetic conditions of extracting the latter from cylindrical and flat pieces made of W+10 % Re by electrical discharges in impulse. The process of extraction of cones was followed by formation of oxide nano-films. Next research is oriented on chemical analysis of oxide nano-films on the Taylor cone surfaces.
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    Rolul Standardelor ISO în dezvoltarea strategică a întreprinderii [Articol]
    (USARB, 2018) Rusnac, Vladislav; Reicu, Andrei
    Any enterprise indiferent of the number of staff, the scope of activating, place of activating, wants an continuous development to achieve the growth of profit. In this case the company is implementing the development strategies. These strategies have as an aim the expansion of the new markets, the local development, the diversification and the modernization. Although all elements listed above are important, they will not have the desired effect without main elements: a well thought strategic plan; a business plan; qualification of human resources; knowledge and performance-standards. Implementing all of the above mentioned elements, leads to a high profit. In this case the entrepreneur is looking for ways to act in the country of origin, but also in the neighboring countries. In such a way the needs to obtain certain certifications in order to promote its products appear. In this situation it is recommended to do audit of quality. The quality audit is performed to obtain the set of documents required for the certification and the confirmation of the correspondence with international standards of the company, in accordance with its business activities. The standardization is one of the most important elements of modern system of quality management.
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    Specifics of Surface Micro-Geometry Modification under the Action of temperature and Electric Field of Electrode Spots [Articol]
    (USARB, 2015) Topală, Pavel; Guzgan, Dorin; Rusnac, Vladislav; Ojegov, Alexandr; Beşliu, Vitalie
    The paper presents the results of experimental research on the possibilities of micro¬machining conductive and semi-conductive materials that gives them new functional properties. It emphasizes that surface micro-geometry modification occurs in practically all cases of the action by concentrated sources of energy, but a prescribed geometry can be reached only under strict conditions. The process of this geometry formation is a function of the physical and mechanical properties and the chemical composition of the processed material, the gradient of applied energy, the intensity of electric field applied in the discharge gap between the workpiece and the tool- electrode. polarity (positive or reverse/negative) in the discharge circuit of the current impulse generator, etc. It is known that on the processed surface can be formed spherical shaped craters, round asperities or Taylor cone shaped asperities. Depending on the shape and the size of asperities, the active surface area, and, respectfully, the emission and absorption properties of elementary particles and light radiation are modified.