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The influence of copper on the decarburization and recrystallization of Fe-Si-Al alloys
Darja Steiner Petrovič, Monika Jenko, Valter Doleček, 2006, original scientific article

Abstract: The decarburization and recrystallization of Fe-Si-Al alloys containing copper was investigated. The decarburization annealing of non-oriented electrical steel sheets produced from Fe-Si-Al alloys depends on the chemical reactions between the gas mixture and the carbon at the steel's surface. The carbon diffusion, the temperature of decarburization annealing, the composition of the gas mixture and the chemical composition of the steel are the influencing parameters that determine the kinetics and the mechanism of decarburization. The decarburization of Fe-Si-Al alloy with the mass fraction of 0.24% and 0.43% of copper was compared with the decarburization of an Fe-Si-Al alloy with a very small amount of copper (0.01%). The decarburization annealing was performed in a H2-H2O gas mixture at 840 °C. The residual carbon content was determined by analytical chemical method. The alloys were also recrystallized in hydrogen at 980 °C. Microstructure of samples after decarburization and recrystallization annealing was investigated with optical microscopy.
Keywords: alloys, recrystallization, decraburization, non-oriented electrical sheet steels, copper, carbon
Published: 10.07.2015; Views: 494; Downloads: 42
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Continuous vertical casting of a NiTi alloy
Aleš Stambolić, Ivan Anžel, Gorazd Lojen, Aleksandra Kocijan, Monika Jenko, Rebeka Rudolf, 2016, original scientific article

Abstract: In this paper we present research that is connected to the performance of a series of experiments combined with the vacuum-induction melting and continuous vertical casting of a NiTi alloy in order to produce the strand. The theoretical chosen parameters made it possible to obtain a continuously cast strand with a diameter of 11 mm. The strand microstructures were investigated with a light and scanning electron microscope, while the chemical composition of the single phase was identified with the semi-quantitative micro-analysis energy-dispersive X-ray spectroscopy and inductively coupled plasma – optical emission spectrometry. The research showed that the microstructure is dendritic, where in the inter-dendritic region the eutectic is composed of a dark NiTi phase and a bright TiNi3–x phase. In some areas we found Ti carbides and phases rich in Fe. The micro-chemical analysis of the NiTi strand showed that the composition changed over the cross and longitudinal sections, which is proof that the as-cast alloys are inhomogeneous. In the final part, the electrochemical behaviours of NiTi strand samples were compared to a commercially available NiTi cast alloy with the same composition.
Keywords: NiTi alloy, continuous vertical casting, microstructure, potentiodynamic and impedance test
Published: 14.03.2017; Views: 598; Downloads: 202
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Hydroxyapatite coatings on Cp-Titanium Grade-2 surfaces prepared with plasma spraying
Rebeka Rudolf, Dragoslav Stamenković, Zoran Aleksić, Monika Jenko, Igor Đorđević, Aleksandar Todorović, Vukoman Jokanović, Karlo Raić, 2015, original scientific article

Abstract: Thin hydroxyapatite coatings were produced on Cp-Titanium Grade-2 samples, with new high-voltage pulse-power equipment PJ-100 (Plasma Jet, Serbia) in order to get a more stable implant structure appropriate for further clinical applications. A comparative analysis of differently prepared surfaces of the Cp-Titanium Grade-2 samples was done before the hydroxyapatite was applied. Microstructural observation of the modified hydroxyapatite/implant surface was done using scanning-electron-microscopy imaging and Auger electron spectroscopy, with the aim of detecting the morphology and the elements contained in the new surfaces of the samples. The results confirmed that the surface of Cp-Titanium Grade-2 modified with hydroxyapatite is very similar to the bone structure.
Keywords: Cp-Ti2 material, hydroxyapatite, plasma, characterization
Published: 16.03.2017; Views: 464; Downloads: 46
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Synthesis of Au nanoparticles prepared with ultrasonic spray pyrolysis and hydrogen reduction
Srečko Stopić, Rebeka Rudolf, Jelena Bogovic, Peter Majerič, Miodrag Čolić, Sergej Tomić, Monika Jenko, Bernd Friedrich, 2013, original scientific article

Abstract: Golden nanoparticles of different sizes and shapes (spherical, cylindrical, triangular and round) where prepared during a synthesis of gold with ultrasonic spray pyrolysis (USP) and hydrogen reduction. The experimental investigations of the (USP) method were performed with an ultrasonic source of 0.8 MHz and 2.5 MHz, acting on the water solution of HAuCl4 forming aerosols with micron-sized and nanosized droplets. The results of the investigation show that the final shape and size of the Au particles depend on the characteristics of the solution and the frequency of the ultrasound. The second step of synthesizing the Au nanoparticles includes the subsequent thermal decomposition of the aerosol droplets in a hydrogen atmosphere between 260°C and 500°C. The investigations showed that the Au nanoparticles prepared in this way are smaller and more homogeneous.
Keywords: gold, ultrasonic spray pyrolysis, reduction, nanoparticles
Published: 21.12.2015; Views: 802; Downloads: 41
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