1. Resolving a structural issue in cerium-nickel-based oxide : single compound or a two-phase system?Jelena Kojčinović, Dalibor Tatar, Stjepan Šarić, Cora Pravda Bartus, Andraž Mavrič, Iztok Arčon, Zvonko Jagličić, Maximilian Mellin, Marcus Einert, Angela Altomare, Rocco Caliandro, 2024, original scientific article Keywords: cerium oxide, nickel oxide, crystallography
Published in DiRROS: 13.03.2024; Views: 332; Downloads: 446
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2. High temperature oxidation of EN AW 7075 aluminium alloyNejc Velikajne, Tilen Balaško, Jaka Burja, Matjaž Godec, Irena Paulin, 2024, published scientific conference contribution Abstract: 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.
Keywords: EN AW 7075, high-temperature oxidation, oxide film, selective laser melting
Published in DiRROS: 28.02.2024; Views: 184; Downloads: 73
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3. Recombination of oxygen atoms on the surface of oxidized polycrystalline nickel—temperature and pressure dependencesDomen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, original scientific article Abstract: The recombination of neutral oxygen atoms in the ground state on the oxidized nickel samples was studied experimentally in the range of pressures where the maximum density occurs in weakly ionized low-pressure oxygen plasma, i.e. between 40 and 200 Pa. The recombination coefficient was determined in the flowing afterglow. The source of oxygen atoms was plasma sustained in a quartz tube of inner diameter 4.7 mm by a microwave discharge in the surfatron mode. The recombination coefficient was determined in the afterglow chamber, which was a Pyrex tube with an inner diameter of 36 mm. The density of oxygen atoms in the afterglow chamber was varied by adjusting the discharge power, the gas flow, the pressure, and the position of a recombinator. Such flexibility of the experimental system enabled adjustment of the temperature of the oxidized nickel samples independently from the O-atom density in its vicinity or other parameters. The density of oxygen atoms in the afterglow chamber at various system parameters was determined by the Šorli method, which is reliable, and has an accuracy of about 20%. The recombination coefficient was determined by calorimetry. The coefficient was inversely proportional to the square root of the pressure and exponentially to the sample temperature. Systematic measurements performed at various pressures and temperatures enabled empirical formula, which were explained qualitatively by recombination kinetics.
Keywords: heterogenous surface recombination, recombination coefficient, nickel, nickel oxide, temperature
Published in DiRROS: 30.08.2023; Views: 350; Downloads: 204
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6. In-depth rheological characterization of tungsten sol-gel inks for inkjet printingUrša Opara Krašovec, Tjaša Vidmar, Marta Klanjšek Gunde, Romana Cerc Korošec, Lidija Slemenik Perše, 2022, original scientific article Keywords: rheology, inkjet printing, tungsten oxide, sol-gel
Published in DiRROS: 11.02.2022; Views: 812; Downloads: 540
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7. Effect of surface oxidation on oxidative propane dehydrogenation over chromia : ǂan ǂab initio multiscale kinetic studyMatej Huš, Drejc Kopač, David Bajec, Blaž Likozar, 2021, original scientific article Keywords: dehydrogenation, chromium oxide, surface oxidation, propane, multiscale modeling
Published in DiRROS: 03.09.2021; Views: 1099; Downloads: 815
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8. First-principles-based multiscale modelling of nonoxidative butane dehydrogenation on Cr [sub] 2O [sub] 3(0001)Drejc Kopač, Damjan Lašič Jurković, Blaž Likozar, Matej Huš, 2020, original scientific article Keywords: butane, nonoxidative, dehydrogenation, first-principles, multiscale modelling, chromium oxide
Published in DiRROS: 13.12.2020; Views: 1566; Downloads: 1028
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