Browsing by Author "Guzgan, Dorin"

Now showing 1 - 13 of 13
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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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    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 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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    Condiţii de formare şi dezvoltare a competenţelor profesionale la studenţi în cadrul disciplinelor tehnico-tehnologice [Articol]
    (USARB, 2014) Rotari, Elena; Guzgan, Dorin
    The paper is devoted to the problem of training requirements for training and skills development to students in technical and technological disciplines. Competence based one of the forms of societal progress. There fore switching to somae new technologies can only be achieved forms of societal progress. There fore switching to somae new technologies can only be achieved actively participate in the process of creativity.
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    Conferirea unei micro-geometriei prescrise a suprafețelor metalice în scopul sporirii intensității curentului de emisie termo-electrică
    (USARB, 2015) Guzgan, Dorin
    The paper presents results of experimental investigations aimed at the construction of cathodes for thermo-electronic emission. The method of pulsed electrical discharge machining was applied to confer a prescribed micro-geometry of the cathode active surface. Modification of the cathode surface micro-geometry involves the extraction and freezing of the Taylor cone meniscuses that are electric field and heat concentrators applied in order to increase the intensity of the thermo-electronic emission current.
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    Experimentul de laborator – Metodă didactică eficientă în cadrul disciplinelor şcolare [Articol]
    (USARB, 2014) Guzgan, Dorin; Guzgan, Natalia
    The right combination of traditional and non traditional methods of teaching-learning-evaluation allows achieving of expected results. Educational reforms have a guide role in the process of competence formation. Their aim is to prepare young generations for better fitting in the today's society. The actual papper is designed for teachers who lead experimental disciplines as Physics, Technological Education, Chemistry and Biology. Here are defined and presented various forms, classifications and phases of planning and organisation of the laboratory experiment.
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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 micro-geometriei suprafeţei catodului în scopul sporirii intensităţii curentului de emisie termo-electronică [Articol]
    (USARB, 2016) Guzgan, Dorin
    The paper presents results of experimental investigations aimed at the construction of cathodes for thermo-electronic emission. The method of pulsed electrical discharge machining was applied to confer a prescribed micro-geometry of the cathode active surface. Modification of the cathode surface micro-geometry involves the extraction and freezing of the Taylor cone meniscuses that are electric field and heat concentrators applied in order to increase the intensity of the thermo-electronic emission current.
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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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    Peculiarity of the Tool-Electrode Wear Mechanism during Surface Machining with Electric Discharges in Pulse [Articol]
    (USARB, 2014) Topală, Pavel; Pînzaru, Natalia; Guzgan, Dorin; Ojegov, Alexandr; Beşliu, Vitalie
    The paper presents the results of experimental research on the wear mechanism of the tool-electrode as a result of machining metal materials by applying electric discharges in pulse. It highlights the requirements that should be followed when designing and developing the tool- electrode. It examines several phenomena noticed on the tool-electrode surface, exactly, the oxide layer formation and the modification of the micro-geometry of the tungsten tool-electrode surface. The paper presents the experimental results on the behavior of the tool-electrode made of stainless steel after the metal parts have been machined. It also presents the phases of mass transfer in the gap between electrodes.
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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.