1. Capacitive energy-storage and electromechanical properties of aerosol-deposited ▫$0.5BaZr_{0.2}Ti_{0.8}O_3–0.5Ba_{0.7}Ca_{0.3}TiO_3$▫ filmsSoukaina Merselmiz, Ivana Goričan, Tadej Rojac, Vid Bobnar, Victor Regis de Moraes, Matej Šadl, Val Fišinger, Nejc Suban, Brigita Kmet, Andreja Benčan, Andraž Bradeško, Andrej Debevec, Barbara Malič, Hana Uršič Nemevšek, 2026, izvirni znanstveni članek Ključne besede: electronic ceramics, powder aerosol composition, thin films, ferroelectricity, energy storage, electromechanical properties
Objavljeno v DiRROS: 08.12.2025; Ogledov: 138; Prenosov: 79
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2. Heat treatment optimisation of 18 % Ni maraging steel produced by DED-ARC for enhancing mechanical propertiesMaja Lindič, Damjan Klobčar, Aleš Nagode, Nikolaj Mole, Borut Žužek, Tomaž Vuherer, 2025, izvirni znanstveni članek Povzetek: This article deals with the Directed Energy Deposition using Wire and Arc (DED-ARC) for maraging steel cladding. A technology for cladding using Gas Metal Arc Welding (GMAW) has been developed that enables the perfect deposition of maraging steel. The material characterisation was carried out in different material states: in the as-built, solution annealed and aged. The research included visual examinations, optical microscopy, Scanning Electron Microscopy / Energy-dispersive X-ray spectroscopy (SEM/EDS), fractography, hardness testing, tensile testing and impact toughness testing. The as-deposited state exhibited a microstructure with very long crystal grains and microsegregations orientated the direction of the heat sink, consisting of lath martensite. Consequently, a subsequent heat treatment is absolutely necessary in order to obtain a uniform fine-grained microstructure. Two different solution annealing processes were analysed, which allowed us to select the most suitable process for the first step of heat treatment followed by aging. A response surface methodology was used to optimise the aging conditions. The results show that additively manufactured maraging steel reaches a tensile strength of 1947 MPa, a hardness of 657 HV5 and a Charpy impact toughness of 11 J at peak aging condition, which is comparable to conventionally manufactured maraging steel.
Ključne besede: maraging steel, heat treatment, material properties optimisation, DED-ARC, GMAW, RSM
Objavljeno v DiRROS: 08.12.2025; Ogledov: 93; Prenosov: 55
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3. Functional determinants for false vacuum decayPietro Baratella, Miha Nemevšek, Katarina Trailović, Yutaro Shoji, Lorenzo Ubaldi, 2025, izvirni znanstveni članek Povzetek: We derive simple expressions to regularise functional determinants from fluctuations of fields with spin 0, 1/2, and 1. These are important for the precise dimensionful determination of false vacuum decay rates. We work in D = 4 Euclidean dimensions and use familiar Feynman diagrammatic techniques with a double expansion in interactions and masses, together with dimensional regularisation in momentum space. We Fourier transform to coordinate space and end up with a simple regularisation prescription in terms of single integrals over the Euclidean radius of field-dependent masses and their derivatives. Our results apply to models with an arbitrary scalar potential and with any number of scalars, fermions, gauge bosons and associated ghosts. We exemplify this approach on the Standard Model with a streamlined calculation of the renormalisation and isolation of divergences in fluctuation determinants.
Ključne besede: false vacuum, decay rates, Higgs properties, multi-Higgs models, functional determinants
Objavljeno v DiRROS: 04.12.2025; Ogledov: 133; Prenosov: 70
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4. Effect of hardening on the magnetic behavior of AISI 1045 steelMario Vukotić, Damijan Miljavec, Jaka Burja, 2025, izvirni znanstveni članek Povzetek: Hardening is an effective method to improve the hardness of the steel construction elements of an electric machine, such as rotor shaft. Surface hardening is typically employed for shafts as it provides a material with hard wear-resistant surface (martensite) and tough and ductile core (ferrite and pearlite), with the transitional zone between them (martensite, ferrite, and pearlite). The investigations were performed on the specimens of AISI 1045 steel, which is commonly used in electric machines. There were three categories of specimens, each of them representing a region in a surface hardened shaft – normalized specimens found in as-delivered steel (core), partially hardened specimens obtained by partial hardening of normalized specimens (transitional zone), and fully hardened specimens (hardened surface), also obtained from the normalized steel. Comparison of the magnetization curves showed that partially and fully hardened specimens exhibited a decrease of saturation magnetic flux density for about 11% and 7%, respectively, compared to the normalized specimens. The magnetizing curves from this study can be directly used in the magnetic simulations of a surface-hardened shaft. This allows more accurate electromagnetic design of electric machines, in which the shaft represents an important part of the magnetic circuit, e.g. two-pole wound-rotor synchronous machine.
Ključne besede: electric machine, hardening, hysteresis loop, magnetic properties, magnetizing curve, microstructure, shaft
Objavljeno v DiRROS: 16.10.2025; Ogledov: 244; Prenosov: 136
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7. Mechanical and microstructural characterization of geopolymer synthesized from low calcium fly ashSabina Dolenec, Vilma Ducman, 2015, izvirni znanstveni članek Povzetek: This study deals with the mechanical and microstructural characterization of geopolymers synthesized from locally available fly ash. A low calcium fly ash was activated using a sodium silicate solution. Samples were characterized by means of flexural and compressive tests, Fourier Transform Infrared (FTIR) spectroscopy, X-ray powder diffraction (XRD), and scanning electron microscopy(SEM). Porosity and pore size distributions were identified using mercury intrusion porosimetry and gas sorption. The compressive strength of the produced geopolymers, which is in the range of 1.6 to 53.3 N/mm2, is strongly related to the water content as well as SiO2/Na2O mass ratio of an alkali activator. The compressive strength significantly increased with decreases in the water content and increased silicon concentration used for the synthesis of geopolymers.
Ključne besede: geopolymers, fly ash, microstructure, mechanical properties
Objavljeno v DiRROS: 05.09.2025; Ogledov: 399; Prenosov: 193
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8. Thermal and mechanical properties of in-house-manufactured PLA and PA filaments at high temperatureNabilah Afiqah Mohd Radzuan, Izzat Mat Samudin, M. S. H. Al-Furjan, Abu Bakar Sulong, Farhana Mohd Foudzi, Muhammad Amin Azman, 2025, izvirni znanstveni članek Ključne besede: polymer composites, additive manufacturing, mechanical properties, finite element analysis
Objavljeno v DiRROS: 01.09.2025; Ogledov: 406; Prenosov: 185
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9. Effect of sulfide in a 0.2 M NaCl solution on copper and pre-oxidized copper in oxic conditionsKlara Prijatelj, Tadeja Kosec, 2025, izvirni znanstveni članek Povzetek: This study investigated copper and pre-oxidized copper immersed in 0.2 M NaCl solutions containing different concentrations of sulfide ions. In order to investigate the corrosion processes, the corrosion potential and electrochemical impedance at room temperature and at an elevated temperature were measured for 24 h during and after exposure to the chloride solution with different sulfide concentrations in aerated conditions. The surfaces of the pre-oxidized copper were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), a focused ion beam scanning electron microscopy (FIB-SEM), and Raman spectroscopy. It was shown that the concentration of sulfide ions in the chloride environments, in addition to the temperature itself, greatly affect the film formation in oxic conditions. The thickness of the films observed corresponds well to those calculated using cathodic stripping voltammetry. The mechanism of corroding copper in chloride/sulfide system was proposed.
Ključne besede: copper, pre-oxidized copper, chloride and sulfide environment, electrochemical properties, surface characterization, Raman, cyclic voltammetry
Objavljeno v DiRROS: 29.08.2025; Ogledov: 420; Prenosov: 267
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