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15. Liquid-copper infiltration and characterization of additively manufactured W-lattice structuresAljaž Iveković, Gokula Krishna Muralidharan, Andrei Galatanu, Guichuan Li, Kim Vanmeensel, Jef Vleugels, 2025, original scientific article Abstract: Tungsten-copper (W-Cu) composites have a wide range of engineering applications, from arc-resistant electrodes and high-voltage electrical contacts to heat sinks for integrated circuits and plasma-facing components for fusion reactors. They combine high corrosion and erosion resistance, very good thermal and electrical conductivity, low thermal expansion, with good mechanical properties. However, the fabrication of such materials is limited in terms of shape complexity and the internal distribution of the individual phases. Furthermore, the dissimilar thermo-mechanical properties (melting temperature, thermal conductivity, coefficient of thermal expansion) of the constituent phases impose severe constraints on the fabrication and use of W-Cu composites. To overcome the challenges of component design and enable greater freedom in terms of composition, W-Cu composites were produced by a combination of additive manufacturing and liquid-melt infiltration (LMI). Porous W-lattice structures were manufactured by laser powder-bed fusion (LPBF) followed by infiltration with molten Cu. A series of composites was produced with Cu contents from 3 to 75 vol% and evaluated in terms of thermal, electrical, and mechanical properties. The LPBF-LMI W-Cu composites exhibited comparable thermo-mechanical properties to W-Cu materials manufactured using powder-metallurgical processing, but with an expanded composition range and shape complexity. Lower thermal expansion coefficients (4.5–5.8 × 10−6 K−1) and an improved thermal stability of the Young’s modulus, only a 27–33 GPa decline in the range 27–827 °C, were observed for all the compositions, which was ascribed to the W-phase connectivity in all the W-Cu composites, independent of the volume fraction of Cu.
Keywords: termomechanical properties, liquid-metal infiltration, laser powder-bed fusion, metal-matrix composites
Published in DiRROS: 07.02.2025; Views: 34; Downloads: 6
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16. Vacuum ultraviolet radiation from gaseous plasma for destruction of water contaminantsMark Zver, Rok Zaplotnik, Miran Mozetič, Alenka Vesel, Arijana Filipić, David Dobnik, Belisa Alcantara Marinho, Gregor Primc, 2025, original scientific article Abstract: Innovative technological solutions are needed for water decontamination to combat the diverse pollutants present in water systems, as no single optimal decontamination technique is appropriate for all circumstances. Vacuum-ultraviolet (V-UV) radiation is a source of energetic photons that break molecular bonds, producing a plethora of chemically reactive agents, most notably OH● radicals, which can cause the degradation of harmful pollutants. Low-pressure gaseous plasma is a good source of V-UV radiation; however, its application to liquid water poses challenges. We constructed an inductively coupled radiofrequency plasma to produce high-intensity V-UV radiation, which was applied to contaminated water via a V-UV-transparent window. Plasma was sustained in hydrogen, as it produces the highest V-UV intensity among all gases at selected discharge parameters. Bacteriophage MS2 was used as an indicator of microbial decontamination efficiency. Reactive oxygen and nitrogen species were measured at various treatment setups to quantify their effect on MS2 inactivation and elucidate the primary inactivation factors. At optimal conditions, the concentration of active virus dropped by 9 log10 PFU/mL in 60 s. The optimal experimental setup was then used to treat bacteria E. coli, S. aureus, antibiotic tetracycline, and synthetic dye methylene blue as representatives of other types of pollutants, all of which were effectively removed/degraded within 10 min of treatment. A comparison of energy efficiency (EEO) to other disinfection setups was made for bacteriophage inactivation. With a low EEO value, we showcase the potential of this technique for further work in this field.
Keywords: water treatment, radical
Published in DiRROS: 07.02.2025; Views: 29; Downloads: 11
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18. Deactivation of copper electrocatalysts during ▫$CO_2$▫ reduction occurs via dissolution and selective redeposition mechanismBlaž Tomc, Marjan Bele, Mohammed Azeezulla Nazrulla, Primož Šket, Matjaž Finšgar, Angelja Kjara Surca, Ana Rebeka Kamšek, Martin Šala, Jan Šiler Hudoklin, Matej Huš, Blaž Likozar, Nejc Hodnik, 2025, original scientific article Keywords: electrochemistry, catalysts, copper, hydrogen production
Published in DiRROS: 07.02.2025; Views: 43; Downloads: 32
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20. O tobožnjem privilegiju akvilejskoga patrijarha Grgura de Montelonga i širenju ingerencija koparske komune na Buje, Oprtalj, Buzet i DvigradJosip Banić, 2017, original scientific article Abstract: Članak utvrđuje epistemološke pretpostavke koje stoje iza tvrdnje da je akvilejski patrijarh Grgur de Montelongo (1251. – 1269.) na početku svoje vlasti (1251. ili 1254.) izdao poseban privilegij koparskoj komuni, davši joj pravo postavljanja podestata iz redova gradskoga plemstva u Bujama, Oprtlju, Buzetu i Dvigradu. To su mišljenje u istarskoj historiografiji popularizirali Pietro Kandler, Carlo de Franceschi i Dane Gruber, sva trojica bez navođenja ikakva izvora, a kasnije su tvrdnju preuzeli Dario Alberi i Darko Darovec. S druge strane, mnogi povjesničari srednjovjekovne povijesti Akvilejskoga patrijarhata i Istre, poput Pija Paschinija i Giovannija de Vergottinija, nigdje ne spominju taj događaj. Nadalje, ni izvorna listina ni njezin prijepis ne nalaze se ni u jednoj objavljenoj zbirci izvora niti u poznatim arhivskim fondovima. Autor zaključuje da je sporno mišljenje prvi formulirao Prospero Petronio u 17. stoljeću, nadovezujući se na Nicolòa Manzuolija, koji je pogrešno povezao koparske privilegije iz 1421. i 1423. s tada već poznatom činjenicom da su koparski plemići u trinaestom stoljeću služili kao podestati u nekim istarskim komunama. Kako se radi o čistoj novovjekovnoj fikciji koja je služila jačanju legitimnosti vlasti koparske komune, tadašnjem neosporivom centru mletačke Istarske provincije, tvrdnja o tobožnjem privilegiju Grgura de Montelonga mora se u potpunosti napustiti.
Keywords: historiografija, horografija, razvijeni srednji vijek, Istra, Kopar, Akvilejski patrijarhat, komune
Published in DiRROS: 06.02.2025; Views: 48; Downloads: 15
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