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Iskalni niz: "ključne besede" (properties) .

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1.
Glass-ceramic engineering:tailoring the microstructure and properties
Christian Rüssel, Wolfgang Wisniewski, 2025, izvirni znanstveni članek

Povzetek: Traditionally, glass-ceramics are inorganic non-metallic materials obtained by the controlled crystallization of a glass. A modern definition has widened this class of materials to solid materials containing at least one glassy and one crystalline phase. The glass is usually obtained by quenching a melt. Re-heating it to a temperature slightly above the glass transition temperature allows nucleation while an often applied second annealing step at a higher temperature causes most of the crystal growth. As in most materials, the composition and the microstructure of glass-ceramics widely governs their properties. The morphology, i.e., size, and aspect ratio of the crystal phases is of special significance and depends on the crystal structure and the occurring growth mechanism. The morphology is also affected by the chemical composition and the temperature/time schedule of the crystallization process, here components of minor concentrations can have a great effect. This review addresses the effects of nucleating agents, phase separation, crystal orientation alignment and stress introduction as tools to tailor the properties of glass-ceramic materials. Future developments in the field of glass-ceramics are discussed.
Ključne besede: glass ceramics, controlled crystallization, microstructure, properties
Objavljeno v DiRROS: 12.02.2025; Ogledov: 32; Prenosov: 36
.pdf Celotno besedilo (28,08 MB)
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2.
Liquid-copper infiltration and characterization of additively manufactured W-lattice structures
Aljaž Iveković, Gokula Krishna Muralidharan, Andrei Galatanu, Guichuan Li, Kim Vanmeensel, Jef Vleugels, 2025, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: termomechanical properties, liquid-metal infiltration, laser powder-bed fusion, metal-matrix composites
Objavljeno v DiRROS: 07.02.2025; Ogledov: 85; Prenosov: 18
.pdf Celotno besedilo (3,44 MB)
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3.
Quality of Slovenian dry-cured ham from Krškopolje and hybrid pigs : Influence of skin trimming methods
Bojana Savić, Martin Škrlep, Nives Marušić Radovčić, Sandra Petričević, Marjeta Čandek-Potokar, 2025, pregledni znanstveni članek

Povzetek: This study examined the quality of dry-cured hams produced from local pig breed and modern hybrids using two trimming methods. Hams (n = 24) of similar weight were harvested from local breed “Krškopolje pig” (KKP) and conventional hybrid pigs (CON). The left and right hams from KKP were trimmed according to “Kraški pršut” (K) and “Istrski pršut” (I), respectively, while the hams from CON were trimmed as “Kraški pršut”, yielding 8 hams per treatment (K-KKP, I-KKP, K-CON). After processing, the samples of dry-cured hams (part with biceps femoris, semimembranosus and semitendinosus muscles) were collected and analysed for chemical composition, texture, sensory analysis and volatile profile. Dry-cured hams of local breed (K-KKP) had lower dehydration loss (due to thicker fat cover), moisture content and aw, softer and more plastic texture, with sensory analysis showing more marbling, softer, pastier texture, more pronounced herbal aroma and sweetness than K-CON. Trimming type was associated with higher dehydration loss (due to removed skin), lower moisture content and aw, higher salt content and harder texture, with sensory analysis showing more marbling, more surface moisture and herbal odour, harder and pastier texture, and sweeter and less bitter taste in I-KKP than K-KKP. The analysis of volatile compounds clearly distinguished the types of dry-cured hams, with each exhibiting a unique volatile profile that enabled differentiation based on breed or trimming. Overall, the study highlights some advantages of dry-cured ham from local pig breeds and shows how trimming affects product's characteristics.
Ključne besede: pigs, dry-cured ham, Krškopolje pig, Kraški pršut, Istrski pršut, physico-chemical properties, volatile profile
Objavljeno v DiRROS: 04.02.2025; Ogledov: 115; Prenosov: 63
.pdf Celotno besedilo (12,07 MB)
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4.
AISI H13 tool steel - comparison between powder bed fused and classically produced parts
Samo Tome, Irena Paulin, Matjaž Godec, 2024, objavljeni znanstveni prispevek na konferenci

Povzetek: AISI H13 Is very commonly used in the hot-work category of steels. Whether it is used as a forging die, a hotcutting tool, or a mold in injection molding or die casting, it is always on the table, as the material of choice. However, its potential has not yet been fully realized. New manufacturing techniques such as additive manufacturing (AM) broaden the horizon of the material’s application, and promise improved performance, through optimized geometry, unobtainable by traditional means, and heightened mechanical properties. One of the more widespread AM processes is Powder Bed Fusion (PBF) where a laser or electron beam constructs the model, by meting a thin coating of metal powder applied to a base plate. By repeatedly applying and melting powder, the end result is a layer-by-layer produced part. However, the techniques for producing such parts are not yet refined enough and require further research. Problems like porosities, part deflection, and crack formation due to residual stress are commonplace, while comparably low mechanical properties in the asprocessed state call for post-production treatments. Naturally, every technique has its boons and drawbacks, and that is what this work aims to analyze - How do the PBF parts compare to classically produced ones, and what are the difficulties in producing the later-mentioned parts.
Ključne besede: powder bed fusion, tool steel, additive manufacturing, mechanical properties
Objavljeno v DiRROS: 16.01.2025; Ogledov: 142; Prenosov: 68
.pdf Celotno besedilo (595,24 KB)
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5.
Hybrid nanostructures of ▫$Fe_3O_4$▫ and Au prepared via coprecipitation and ultrasonic spray pyrolysis
Lan Kresnik, Peter Majerič, Darja Feizpour, Klementina Pušnik Črešnar, Rebeka Rudolf, 2024, izvirni znanstveni članek

Povzetek: The coupled processes of coprecipitation and ultrasonic spray pyrolysis (USP) were used to synthesize Fe3O4-Au hybrid nanostructures. The first coprecipitation method enabled the synthesis of Fe3O4 nanoparticles by mixing iron salts’ ions (Fe2+ and Fe3+) and ammonia as the base, and USP was used as the coating process of the Fe3O4 nanoparticles with Au. The formatted hybrid nanostructures consist of Fe3O4 nanoparticles that have Au on their surface in the form of gold nanoparticles (AuNPs). AuNPs have a crystalline structure and range in size from 10 to 200 nm. Additional characterization techniques, including ICP-OES, TEM, SEM, EDS, DLS, zeta potential, and room temperature magnetic hysteresis loops, were used to determine the chemical, physical, and magnetic properties of the Fe3O4 nanoparticles and hybrid nanostructures. It was found that USP produces separate AuNPs too (not just on the Fe3O4 surface), suggesting a bimodal formation of AuNPs. The zeta potential of the Fe3O4 nanoparticles showed poor stability (−15 mV), indicating a high tendency to aggregate, and the zeta potential of the hybrid nanostructures was also very low (≅0), which, comparatively means even worse stability. The saturation magnetization of the Fe3O4 nanoparticles was 35 emu/g, which is relatively lower than that of bulk Fe3O4, while the saturation magnetization of the hybrid nanostructures was significantly lower (0.1 emu/g) compared to the Fe3O4 nanoparticles.
Ključne besede: magnetic NPs, gold NPs, transmission electron microscopy, magnetic properties
Objavljeno v DiRROS: 08.01.2025; Ogledov: 176; Prenosov: 97
.pdf Celotno besedilo (7,35 MB)
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6.
Evaluation of the magnetic properties of Ag-Au-Pd-Cu dental alloys
Leo Gusel, Peter Majerič, Mirko Glišić, Aleksandra Kocijan, Rebeka Rudolf, 2024, izvirni znanstveni članek

Ključne besede: magnetic properties, noble dental alloys, characterization
Objavljeno v DiRROS: 24.12.2024; Ogledov: 186; Prenosov: 85
.pdf Celotno besedilo (3,81 MB)
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7.
Investigating the synergistic impact of freeze-thaw cycles and deicing salts on the properties of cementitious composites incorporating natural fibers and fly ash
Ildikó Merta, Vesna Zalar Serjun, Alenka Mauko Pranjić, Aljoša Šajna, Mateja Štefančič, Bojan Poletanovic, Farshad Ameri, Ana Mladenović, 2025, izvirni znanstveni članek

Povzetek: In cold climates, concrete structures confront durability challenges due to harsh conditions. This study evaluates the effects of incorporating natural fibers, such as hemp and flax fibers (at 1 vol%), and partially replacing cement with fly ash (at 25 and 50 wt%) on the properties of cementitious composites subjected to accelerated aging under freeze-thaw cycles and deicing salts. Findings reveal that natural fibers enhance the freeze-thaw resistance, reducing deterioration (scaling) to 5-8% after 56 cycles. When mortars were subjected to accelerated freeze-thaw cycles, the compressive strength of plain mortar significantly decreased (up to 57%). However, adding natural fibers to the matrix substantially reduced its compressive strength loss. In the case of flexural strength, plain mortars experienced 33% loss, while hemp, flax, and polypropylene fiber mortars showed only 13%, 23%, and 10% losses, respectively. Furthermore, mortars experience a notable enhancement in their energy absorption capacity when reinforced with natural fibers, particularly with hemp fibers (up to 348% higher than plain mortar). Under harsh conditions, hemp and flax-reinforced mortars, with 25wt% fly ash replacement, lose the compressive strength significantly however still demonstrate an alternative to synthetic fibers in terms of flexural strength. Even with 25wt% of fly ash, mortars with natural fiber reinforcement display significantly superior energy absorption capacities compared to plain mortars (up to 48%).
Ključne besede: cementitious composites, natural fibers, freeze-thaw cycles, mechanical properties, mass loss, fly ash
Objavljeno v DiRROS: 23.12.2024; Ogledov: 261; Prenosov: 95
.pdf Celotno besedilo (10,99 MB)
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8.
Effects of different China and ball clays on traditional ceramic process : a multi-methodological approach
Andreas Bernasconi, Nicoletta Marinoni, Lucia Mancini, Marco Voltolini, Fernando Francescon, R. Sartori, Alessandro Pavese, 2024, izvirni znanstveni članek

Povzetek: A combination of technological properties, mineralogical composition and three-dimension (3D) imaging is proposed to get insights into sanitary-ware ceramic bodies of the Vitreous-China technology as a function of the different clay raw materials used in the formulation of slip. Particular attention is paid to the effects induced along the production chain, during casting, after drying (dried body) and after firing (fired body). The different combinations of China and ball clays lead to different casting behaviour, in first instance, and to different mechanical strength, then, due to variations in the particle size distribution rather than in the mineralogical composition. In particular, the finer the particle size, the finer the pore size and, in addition, the better the mechanical properties (with a maximum of 4.7 MPa), due to a better packing. However, fine particle size distribution worsens the slip’s behaviour into moulds, impacting negatively on productivity, with a 17 % reduction of casting thickness. Upon firing process, such differences are mitigated by the body densification and result in more similar pores’ distributions, though the importance of the mineralogical composition is revealed. In fact, differences in mineralogical phases’ contents and in kaolinite HI index guide the comprehension of high temperature phase evolution and technological properties like the fired body thermal expansion, foremost via residual quartz. These results are important for a plastic raw materials’s selection within the ceramic sanitary-ware process.
Ključne besede: clay raw materials, vitreous-China technology, synchrotron X-ray microtomography, X-ray diffraction, ceramic properties, phase analysis
Objavljeno v DiRROS: 16.12.2024; Ogledov: 146; Prenosov: 115
.pdf Celotno besedilo (3,59 MB)
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9.
The effectiveness of neuromuscular training warm-up program for injury preventionin adolescent male basketball players
Armin Paravlić, Peter Bakalár, Katarina Puš, Saša Pišot, Miloš Kalc, Kaja Teraž, Luka Šlosar, Manca Peskar, Uroš Marušič, Boštjan Šimunič, 2024, izvirni znanstveni članek

Povzetek: This study evaluated the effects of a neuromuscular training (NMT) warm-up program on injury incidence,neuromuscular function, and program adherence, maintenance and acceptance in adolescent basketballplayers. A total of 275 players from 20 Slovenian teams (15 ± 1.7 years of age), were randomized into anintervention group (IG, n=129) and a control group (CG, n=146). Over three months, the IG incorporatedNMT into their warm-ups, while the CG followed their usual practice. Measurements of body anthro-pometry, muscle contractile properties, and balance were taken before and after the intervention. Also,the injury incidence, training adherence and maintenance were reported. Both groups showed improvedbalance, with no significant difference between them. However, IG demonstrated reduced delay times inspecific muscles, indicating improved neuromuscular function. Injury prevalence proportion (%) duringthe whole study period was higher in the control group compared to intervention (IG: 10.9% vs. CG:23.3%), and incidence rate. Moreover, the incidence rate ratio for sustaining an injury was 2.6 on average(ranging from 0.88 to 7.07 for tendon and muscle injuries, respectively), indicating significantly lowerinjury risk in IG than CG. These findings highlight the effectiveness of NMT warm-ups in reducing injuryrisk and enhancing neuromuscular function, emphasizing the value of structured injury preventionstrategies in youth sports.
Ključne besede: muscle contractile properties, balance, injury prevalence, training adherence
Objavljeno v DiRROS: 18.11.2024; Ogledov: 237; Prenosov: 121
.pdf Celotno besedilo (895,08 KB)
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10.
Laser powder bed fusion parameters optimization for enhanced mechanical properties of EOS Co-Cr dental alloy
Dalibor Viderščak, Zdravko Schauperl, Biserka Runje, Sanja Šolić, Amir Ćatić, Matjaž Godec, Irena Paulin, Črtomir Donik, 2024, izvirni znanstveni članek

Povzetek: This research explores how variations in laser powder bed fusion (LPBF) parameters—laser power (P), scanning speed (v), and base plate preheating temperature (ϑp)—affect the mechanical properties of the EOS Co-Cr SP2 dental alloy. A central composite design (CCD) was used to optimize the process parameters. Mechanical testing focused on crucial properties for dental applications, including yield strength (Rp0.2), elongation (ε), toughness (KVa), and flexural strength (Rms). Microstructural analysis was conducted using light and electron microscopy, while XRD identified microstructural phases. Statistical analysis (ANOVA, Scheffé post hoc test, α = 0.05) revealed significant effects of P, v, and ϑp on the mechanical properties. Response surface models (RSMs) were developed, and optimal parameters were determined to achieve maximum toughness and flexural strength. Maximum values were obtained with laser power above 205Wand base plate preheating at 310 ◦C. The mathematical model predicted toughness values with less than 5% deviation from experimental results, indicating high accuracy.
Ključne besede: LPBF, production parameters, Co-Cr dental alloy, CCD, mechanical properties, ANOVA
Objavljeno v DiRROS: 18.10.2024; Ogledov: 277; Prenosov: 8214
.pdf Celotno besedilo (8,69 MB)
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