Browsing by Author "Medňanský, Martin"

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    Accompanying phenomena during casting of aluminium alloys
    (University of Žilina, 2023) Galčík, Marek; Brůna, Marek; Medňanský, Martin
    An oxide layer is formed on the surface of a molten aluminium alloy when it is exposed to the surrounding atmosphere. The oxide layer on the surface of the melt is not harmful. The problem occurs when it is entrained into the melt volume and solidifies in the casting. The paper deals with the formation of the oxide layer, its types and the formation of a double oxide layers.
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    Hodnotenie vplyvu technologických parametrov na mikroštrutúru vysokotlakových odliatkov
    (Žilinská univerzita v Žiline, 2023) Medňanský, Martin; Brůna, Marek; Matejka, Marek
    A number of technological parameters influence the mechanical properties of a high pressure die casting. The aim of the presented paper was to perform microstructural analysis of AlSi9Cu3(Fe) alloy casting fabricated with high-pressure die casting (HPDC) technology. Several castings with varying casting parameter – maximum plunger speed vmax were cast. In pre-selected critical spots, the effect of vmax was observed on the shape and size of the structural components, where at lower vmax the eutectic Si shortened in length and thickened. EDS analysis determined found intermetallic phases to be α-Al(Fe,Mn,Cr)Si in the shape of a rhombic dodecahedron with sizes as small as 2 µm and Al2Cu being present in both modifications – oblong grains and globular ternary eutectic. There was no significant change in microhardness of α(Al) phase found, that would be caused by the varying vmax
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    Štruktúra hliníkových zliatin pre vysokotlakové odlievanie
    (University of Žilina, 2023) Medňanský, Martin; Brůna, Marek; Matejka, Marek
    The aim of the presented paper was to carry out a review of the internal structure of alloys used for high pressure die casting (HPDC) and to experimentally perform a structural analysis of AlSi9Cu3(Fe) alloy. Several castings with varying casting parameter – maximum plunger speed vmax were cast. In pre-selected critical locations, a change in porosity was observed with the change of the speed, and the casting samples with vmax = 2 and 3 m∙s-1 showed the lowest porosity. The effect of vmax was also observed on the shape and size of the structural components, where at higher vmax the eutectic Si grew in length and decreased in thickness. EDS analysis determined found intermetallic phases to be α-Al(Fe,Mn,Cr)Si in the shape of a rhombic dodecahedron with sizes as small as 2 µm and Al2Cu occurring in both modifications – oblong grains and globular ternary eutectic.
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    Technológ 3/2022
    (Žilinská univerzita v Žiline, 2022) Sýkorová, Martina; Bolibruchová, Dana; Bílik, Jozef; Sobota, Róbert; Šuba, Roland; Mojžiš, Milan; Litvaj, Ivan; Dižo, Ján; Blatnický, Miroslav; Ishchuk, Vadym; Molnár, Denis; Štaffenová, Katarína; Rakyta, Miroslav; Bubeník, Peter; Biňasová, Vladimíra; Kasajová, Marta; Tarbajovský, Pavol; Puškár, Michal; Абович Подригало, Михаил; Петрович Кравченко, Александр; Герлици, Юрай; Сергеевич Шеин, Виталий; Сергеевич Ткаченко, Александр; Александровна Кравченко, Екатерина; Kantoríková, Elena; Koňár, Radoslav; Matejka, Marek; Podprocká, Radka; Kostrzewski, Mariusz; Jerzy Nowak, Wojciech; Medňanský, Martin; Brůna, Marek
    Vplyv teploty precipitačného vytvrdzovania na vlastnosti zliatiny AlSi5Cu2Mg legovanej Zr || Seamless Tubes Manufacturing Processes Analysis || Decision-making process and knowledge management, knowledge management and skills || Nákladné prívesy za traktor - koncepčné usporiadanie a ich typy || Proces reverzného inžinierstva s využitím 3D laserového skenovania || Nákladné prívesy za traktor - špeciálne verzie a zvláštna výbava || Knowledge, knowledge management and innovations || Návrh modelu parného rušňa || Integrovaný systém pre redukciu emisií spaľovacích motorov || Technical preparation of production || О выборе мощности двигателя автомобиля на этапе проектирования || Vplyv tepelného spracovania na nástrojové ocele || Skúsenosti pri ultrazvukovom skúšaní zvarov v praxi || Hodnotenie tepelného zaťaženia vysokotlakovej formy pomocou numerickej simulácie || Rzeczy kilka o transporcie kolejowym ładunków w Japonii || Precipitačné vytvrdzovanie Al-Si-Cu-Mg zliatin || Numerické simulácie vplyvu technologických faktorov na štruktúru vysokotlakových odliatkov
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    Výskum hybridných hliníkových odliatkov s použitím penových jadier
    (University of Žilina, 2024) Medňanský, Martin; Brůna, Marek
    The paper focuses on the technological challenges posed by the production of experimental hybrid castings by overcasting technology. Theoretically, using this technology provides lower casting weight while maintaining positive mechanical properties and improves the energy absorption capability of the component. The effect of the pressure used during the foaming of the cores on the relative density of the metal foam component was experimentally evaluated. The challenge of the technology is the interface between the casting and the oxide coated core surface. Surface-treated cores were cast and their interfaces were observed microscopically. The experimental results showed a positive effect of the presence of AlPO4 in the interface to prevent the penetration of liquid metal into the pores of the foam core.