1. Kako podnebne spremembe in velikopovršinske motnje vplivajo na naravne ekosisteme? : učno gradivo pri predmetu Globalne spremembe in gozdni ekosistemi, BF Odd. za gozdarstvo in obnovljive gozdne vireLado Kutnar, 2024, drugo učno gradivo Ključne besede: podnebne spremembe, motnje, temperature, gozdni ekosistemi, drevesne vrste, pričakovana razporeditev gozdov, model, IPCC, ARSO, Slovenija Objavljeno v DiRROS: 03.04.2024; Ogledov: 46; Prenosov: 0 |
2. Effect of post-treated low-temperature plasma nitriding on the wear and corrosion resistance of 316L stainless steel manufactured by laser powder-bed fusionMatjaž Godec, Črtomir Donik, Aleksandra Kocijan, Bojan Podgornik, Danijela Anica Skobir Balantič, 2020, izvirni znanstveni članek Ključne besede: austenitic stainless steel, powder bed fusion, low-temperature plasma nitriding, wear and corrosion behaviour, dislocation cell structure Objavljeno v DiRROS: 25.03.2024; Ogledov: 91; Prenosov: 60 Celotno besedilo (3,28 MB) Gradivo ima več datotek! Več... |
3. Understanding carbide evolution and surface chemistry during deep cryogenic treatment in high-alloyed ferrous alloyPatricia Jovičević Klug, Levi Tegg, Matic Klug Jovičević, Rahul Parmar, Matteo Amati, Luca Gregoratti, László Almásy, Julie M. Cairney, Bojan Podgornik, 2023, izvirni znanstveni članek Ključne besede: cryogenic temperature, surface chemistry, microstructure, atom probe tomography (APT), scanning photoelectron microscopy (SPEM), small angle neutron scattering (SANS) Objavljeno v DiRROS: 08.03.2024; Ogledov: 90; Prenosov: 89 Celotno besedilo (20,08 MB) Gradivo ima več datotek! Več... |
4. High temperature oxidation of EN AW 7075 aluminium alloyNejc Velikajne, Tilen Balaško, Jaka Burja, Matjaž Godec, Irena Paulin, 2024, objavljeni znanstveni prispevek na konferenci Povzetek: Aluminium alloys are highly valued for their exceptional strength-to-weight ratio, making them a preferred choice in structural applications. Among these alloys, EN AW 7075 stands out for its superior mechanical properties, finding widespread use in industries such as aerospace, mechanical engineering, and sports equipment. This study investigates the high-temperature oxidation behavior of EN AW 7075 alloy. The gathered results can provide valuable insights into the behavior of the mentioned alloy during the selective laser melting (SLM) process. These results can contribute to a better understanding of how the alloy responds to specific conditions and parameters. SLM is an additive manufacturing technique. The process involves the sequential steps of preheating, melting, and rapid cooling of metal powder. To minimize the influence of oxygen, the build chamber is filled with inert gas. A protective argon atmosphere is continuously maintained. However, despite these precautions, oxidation can still occur, leading to potential issues in the final product. Hence, we examined the oxidation kinetics of the EN AW 7075 alloy in an oxygen atmosphere in the temperature range of 300-500 °C. The findings of this investigation significantly contribute to an understanding of the behavior of the alloy during high-temperature oxidation, particularly for ongoing studies focused on processing Al-Zn-Mg-Cu alloys using the selective laser melting technique. Thermogravimetry was employed to analyze the oxidizing behavior, with three samples subjected to a 6-hour exposure in an oxidizing atmosphere at temperatures of 300, 400, and 500 °C. Surprisingly, no oxidation occurred, as indicated by the negligible and negative changes in mass observed across all samples. Ključne besede: EN AW 7075, high-temperature oxidation, oxide film, selective laser melting Objavljeno v DiRROS: 28.02.2024; Ogledov: 149; Prenosov: 63 Celotno besedilo (897,18 KB) Gradivo ima več datotek! Več... |
5. Solidification behavior of Fe-6.5Si alloy powder for AM-SLM processing, as assessed by differential scanning calorimetryDarja Steiner Petrovič, Črtomir Donik, Irena Paulin, Matjaž Godec, Maja Vončina, Martin Petrun, 2023, izvirni znanstveni članek Ključne besede: soft magnetic alloy, differential scanning calorimetry, oxygen, high-temperature phase, microstructure, eutectics Objavljeno v DiRROS: 02.02.2024; Ogledov: 137; Prenosov: 66 Celotno besedilo (9,05 MB) Gradivo ima več datotek! Več... |
6. High-temperature oxidation of boiler steels at 650 °CJaka Burja, Barbara Šetina, Borut Žužek, Tilen Balaško, 2023, izvirni znanstveni članek Povzetek: This study presents a comprehensive investigation of the formation, composition and
behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3,
13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the oxidation
damage due to short-term overheating. The research combines CALPHAD (CALculation of PHAse
Diagrams) calculations, thermogravimetric analysis (TGA) and advanced microscopy techniques, in-
cluding scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), to elucidate
the complex mechanisms controlling oxidation kinetics and oxide layer development. CALPHAD
calculations were used to determine the thermodynamically stable phases for each steel type at 650
◦C and different oxygen activities. The results showed different phase compositions, highlighting
the importance of the chromium content in steel for the formation of oxide layers. The different
oxidation kinetics and oxide layer compositions are presented and associated with the increased risk
of material degradation due to overheating. These results have significant implications for industrial
applications, mainly the susceptibility to oxidation of low-alloyed steels like 16Mo3 and 13 Cr and
contribute to a deeper understanding of oxidation processes in steels. Ključne besede: high-temperature oxidation, thermogravimetric analysis, kinetics, CALPHAD, boiler steels, SEM, EBSD Objavljeno v DiRROS: 26.01.2024; Ogledov: 217; Prenosov: 104 Celotno besedilo (12,99 MB) Gradivo ima več datotek! Več... |
7. High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V contentBojan Podgornik, Marko Sedlaček, Barbara Šetina, Miha Čekada, 2023, izvirni znanstveni članek Ključne besede: (Cr, V)N coating, galling, high-temperature tribology, hot forming, self-lubrication Objavljeno v DiRROS: 26.01.2024; Ogledov: 188; Prenosov: 121 Celotno besedilo (12,53 MB) Gradivo ima več datotek! Več... |
8. Temperature pre-treatment of gypsum for powder based 3D printing technologyVesna Zalar Serjun, Lidija Korat, 2021, objavljeni znanstveni prispevek na konferenci Povzetek: In recent years many researchers have been involved in studies in the field of pre-treatment of various raw materials. Temperature treatment of materials results in several advantages, which have been already recognised and successfully applied in various fields of applications. Where at the same time, the practices has been adopted also in the field of 3D printing. Enhanced strength and stiffness, assuring desirable performance criteria of the 3D printed models, reflect the most important characteristics. 3D printing binder jetting technology is based on the application of liquid binders onto powdered material, where gypsum powders have been commercially used as a base raw material. As natural raw materials can be replaced by other materials, such as recycled industrial by products, the aim of this research work was to evaluate the potential usage of three synthetic gypsum powders from different industrial processes for 3D printing. The investigation covered (a) mineralogical and microstructural characteristics of gypsums from different origin and (b) the effect of pre-treatment of gypsum powders at different temperatures (up to 500 °C). On the basis of the results, the most promising temperature regime for each different waste gypsum powder treatment, reflecting in the most optimal setting time, was defined. Synthetic gypsums were characterized by X-ray diffraction (QXRD), scanning electron microscopy (SEM) and differential thermal analysis (TG/DTA). The results showed that all three synthetic gypsums (calcium sulfate dihydrate, CaSO 4∙2H2O) thermally degrade into calcium sulfate anhydrite (CaSO 4) via an intermediate calcium sulfate hemihydrate (CaSO 4∙ ½H2 O, bassanite) phase. Microstructural and mineralogical differences were observed when temperature treated gypsums from different origins were compared. The detailed knowledge of gypsum powder properties at different temperature regime is important parameter for the assurance of 3D printing key parameters such as flowability, roughness and wettability, especially for determination of saturation levels and setting time. After all, these parameters define final mechanical properties of 3D printed structures. By using such approach, the understanding of material compatibility for 3D printing technology can be defined and improved if necessary. Ključne besede: 3D print, additive manufacturing, gypsum, temperature Objavljeno v DiRROS: 25.01.2024; Ogledov: 164; Prenosov: 111 Celotno besedilo (9,29 MB) Gradivo ima več datotek! Več... |
9. Experimental study and thermodynamic modelling of the temperature effect on the hydration of belite-ye’elimite-ferrite cementsMaruša Mrak, Frank Winnefeld, Barbara Lothenbach, Andraž Legat, Sabina Dolenec, 2024, izvirni znanstveni članek Povzetek: This study focuses on the kinetics of hydration, phase assemblage, microstructure and mechanical properties after various hydration times of two different BCSA cements at 5, 20, 40 and 60 ◦C and compares experimental data with thermodynamic modelling. Different curing temperatures change the type of hydrates and their amounts. Ye’elimite and gypsum in belite-ye’elimite-ferrite cements are almost fully reacted after 24 h of hydration at 20, 40 and 60 ◦C, while not at 5 ◦C. The hydration of belite is slower than the one of ye’elimite, but reaches a high degree of hydration after 150 days which is increasing with temperature. Less ettringite is present at elevated temperatures due to its increasing solubility, while more monosulfate is observed. Furthermore, with increasing temperature siliceous hydrogarnet forms at the expenses of strätlingite as well as more C S H is found as more belite reacts resulting in higher compressive strength. Dense and homogenous microstructure is observed at 5 ◦C, while it is more heterogeneous at higher temperatures. The presence of more ye’elimite resulted in higher ettringite and str¨atlingite formation and a higher compressive strength, while more belite yields more C S H in the hydrates and lower compressive strength. Ključne besede: belite-ye’elimite-ferrite cement, temperature, hydration, thermodynamic modelling Objavljeno v DiRROS: 11.12.2023; Ogledov: 153; Prenosov: 132 Celotno besedilo (9,96 MB) Gradivo ima več datotek! Več... |
10. Effects of specific parameters on simulations of energy use and air temperatures in offices equipped with radiant heating/cooling panelsSabina Jordan, Jože Hafner, Martina Zbašnik-Senegačnik, Andraž Legat, 2019, izvirni znanstveni članek Povzetek: When creating a simulation model to assess the performance of buildings, there is usually a lack of feedback information. Only in the case of measurements of a real building is a direct comparison of the measured values and simulated results possible. Parameter data related to users’ behavior or other events can also be obtained. Their evaluated frequency, magnitude and duration, along with boundary conditions, are crucial for the results. It is clear that none of them can be predicted very accurately. Most of them, however, are needed for computer modeling. In this paper we analyzed the well-defined TRNSYS simulation model of offices equipped with radiant ceiling panels for heating and cooling. The model was based on real case offices and was validated based on measurements for 1 year. The analysis included simulations in order to define what effect the parameters related mainly to users have on the energy use and the indoor air temperatures. The study confirmed that specific human activities influence the annual energy use to a relatively small degree and that their effects often counteract. It also confirmed the even more important fact that although small, these activities can influence the thermal comfort of users. It is believed that despite the fact that this research was based on an analysis of offices equipped with radiant ceiling panels, most of the results could be applied generally. Ključne besede: measurements, modeling, simulation, validation, analysis, energy use, temperature Objavljeno v DiRROS: 15.09.2023; Ogledov: 285; Prenosov: 137 Celotno besedilo (1,83 MB) Gradivo ima več datotek! Več... |