| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme


1 - 9 / 9
First pagePrevious page1Next pageLast page
Celovita učinkovitost opreme v Omco Metals Slovenia d.o.o. : magistrsko delo
Denis Arnšek, 2023, master's thesis

Abstract: Vpeljava kazalnika OEE (celovita učinkovitost opreme) omogoča podjetju zaznavanje ključnih pomanjkljivosti v proizvodnjem procesu in posledično optimizacijo le-tega. V nalogi je najprej predstavljen kazalnik OEE in njegovo teoretično ozadje. Osrednji del naloge predstavlja analiza učinkovitosti opreme (proizvodne linije) v obravnavanem podjetju. Vse 3 postavljene hipoteze so izračuni potrdili, kar kaže na precejšenj potencial za izboljšave. Za konec so podani predlogi za nadaljno vpeljavo kazalnika in možne izboljšave procesa s ciljem optimizacije proizvodnje.
Keywords: OEE, celovita učinkovitost opreme, OMCO Metals Slovenia d.o.o., razpoložljivost, zmogljivost, kakovost
Published in DKUM: 02.06.2023; Views: 173; Downloads: 0
.pdf Full text (2,50 MB)

Analysis of trace heavy metals in a sample droplet with lab-on-a-chip system : diplomsko delo univerzitetnega študijskega programa I. stopnje
Nika Žurga, 2020, undergraduate thesis

Abstract: The aim of this work was to develop and validate an electroanalytical method for simultaneous determination of Zn(II), Cd(II), and Pb(II) in a sample droplet with lab-on-a-chip system. Unmodified screen-printed electrodes (bare SPE using Ag/AgCl reference electrode) and Bi-film SPEs (BiFSPE) were used as electrochemical sensors. Cyclic voltammetry of [Fe(CN)6]3–/[Fe(CN)6]4– redox couple was employed for testing the reversibility of the diffusion-controlled system and square-wave anodic stripping voltammetry (SWASV) for determination of Zn(II), Cd(II), and Pb(II). SWASV was performed at deposition potential of –1.5 V vs. Ag/AgCl and deposition time of 60 s. The following validation parameters were examined: limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and precision. LOD and LOQ for Zn(II) were both lower with BiFSPE than with bare SPE. For Cd(II), LOD and LOQ were similar for both bare SPE and BiFSPE. For Pb(II), LOD and LOQ with bare SPE could not be determined (due to intense background contribution) but were obtained with BiFSPE. Linear concentration ranges were obtained for all analytes with bare SPE and BiFSPE. Accuracy and precision were evaluated for different spiked concentrations; however, the method with bare SPE was neither accurate nor precise. With BiFSPE, the method was found to be both accurate and precise for Pb(II) at a spiked concentration of 140.0 μg/L, but not for Zn(II) or Cd(II). For the latter, problems with accuracy and precision were encountered with both bare SPE and BiFSPE. Both methods were selective for Zn(II), Cd(II), and Pb(II) determination. It can be concluded that the optimization of both methods is required for future studies.
Keywords: SPE, BiFSPE, heavy metals determination, SWASV, validation
Published in DKUM: 31.08.2020; Views: 887; Downloads: 168
.pdf Full text (1,91 MB)

Determination of microstructural changes by severely plastically deformed copper-aluminum alloy : optical study
Nebojša Romčević, M. Gilić, Ivan Anžel, Rebeka Rudolf, Miodrag Mitrić, M. Romčević, B. Hadžić, D. Joksimović, Milica Petrović Damjanović, Matija Kos, 2014, original scientific article

Abstract: Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metal matrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of $Cu$, $CuO$, $Cu_2O$, $Cu_4O_3$ or $Al_2O_3$ structural characteristics, depending on type of sample.
Keywords: metals, oxides, atomic force microscopy, Raman spectroscopy, microstructure
Published in DKUM: 08.08.2017; Views: 1451; Downloads: 150
.pdf Full text (596,63 KB)
This document has many files! More...

Synthesis and structure of transition metal bisalkinylselenolato complexes
Rudolf Pietschnig, Carmen Moser, Stefan Spirk, Sven Schäfer, 2005, published scientific conference contribution

Abstract: We synthesized closely related cis and trans platinum complexes of SeCC-n-C5H11 and elucidated their structures in solution and the crystalline state. In line with previous work we find exclusive coordination of the selenium atom of the ambident alkynylselenolate ligand and a preference for the obviously more stable trans isomer. In contrast to previous work we find auniform increase of all metal ligand bond lengths in the cis vs. the trans isomers. Moreover we studied the coordination of alkynykselenolate ligands to group 4 metals.
Keywords: analytical chemistry, isomers, stability, metals
Published in DKUM: 22.06.2017; Views: 1017; Downloads: 341
.pdf Full text (614,73 KB)
This document has many files! More...

Sensing heavy metals using mesoporous-based optical chemical sensors
Špela Korent Urek, Nina Frančič, Matejka Turel, Aleksandra Lobnik, 2013, review article

Abstract: Heavymetal pollution is one of the more serious environmental problems; therefore, there is a constant demand for the development of new analytical tools for its monitoring. An optical chemical sensor represents a good alternative to classical instrumental methods.The mesoporous materials used in optical chemical sensorsʼ fabrications have properties such as high porosity, exceptional adsorption capacity, tuneable 3D shape, geometry, and morphology, which enable improved limit of detection, response time, and selectivity properties of optical sensors. In this review, we firstly present the properties of mesoporous materials, provide a brief description of sensing mechanisms, and briefly discuss the importance of continuous monitoring. Recent advances in those mesoporous silica-based optical sensors used for heavy metal detection have been reported and their advantages and limitations also discussed. This review covers publications that have appeared since 2008.
Keywords: heavy metals, magnetic properties, structural properties, heavy metal pollution
Published in DKUM: 14.06.2017; Views: 2455; Downloads: 325
.pdf Full text (3,19 MB)
This document has many files! More...

Protection of copper and its alloys using corrosion inhibitor-literature review
Milorad V. Tomić, Miomir Pavlović, Milovan Jotanović, Regina Fuchs-Godec, 2010, original scientific article

Abstract: A review of the literature dealing with the electrochemical corrosion of copper and its alloys with purpose to find the most suitable inhibitor for its protection has been done. According to their chemical composition of corrosion inhibitors are divided into inorganic and organic inhibitors. Inhibition of alloying metals are possible (such as the addition of arsenic alloy components in brass, preventing its unzincanization). The paper reviews the theoretical basis of application of inhibitors to protect metals from corrosion as well as an overview of current research application of inhibitorsto protect copper and copper alloys. Benzotriazole (BTA) is most often used corrosion inhibitor for copper and its alloys in acidic and alkaline solution, because of its high inhibition efficiency. The lowest concentration of inhibitor for protection of copper in various solutions was 0.05%, and for the protection of copper in contact with steel is 0.1%. On the surface of copper and brass BTA forms a protective Cu-BTA film. However, BTA is like many other synthesized organic inhibitors is very toxic and if used invery small concentrations. It turnedout that the AETD, AETDA and PTAT good corrosion inhibitors of copper mixed type with the efficiency of inhibition increases with concentration. Due to the adverse effects on the environment, health and other bodies in recent times the focus of researchis transferred to the inhibiting action of biological molecules or mixtures of natural compounds called "Green inhibitors".
Keywords: corrosion inhibitors, protection of metals, inorganic inhibitors, organic inhibitors, alloys elements, green inhibitors
Published in DKUM: 31.05.2012; Views: 2289; Downloads: 119
URL Link to full text

Optical properties of plastically deformed copper
J. Trajić, Rebeka Rudolf, Ivan Anžel, M. Romčević, N. Lazarević, M. Mirić, Z. Lazarević, B. Hadžić, Nebojša Romčević, 2010, published scientific conference contribution

Abstract: Pure copper (99.99), prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm, was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing (ECAP). ECAP was applied as an effective technique for producing bulk nano-scaled structures. Optical properties of the sample were investigated using Raman spectroscopy. Two types of lines: narrow (with width of 7 cm¡1) and wide ( 40 cm¡1) are registered. Existence of two types of lines indicates that in the specimen exists nano-sized crystal structures of both Cu and CuO related with three dimensional amorphous boundary spaces, which indicates that plastic deformation of the sample did not lead to total amorphisation of the specimen.
Keywords: plastically deformed copper, hydrometallurgical extraction of metals
Published in DKUM: 31.05.2012; Views: 2006; Downloads: 115
URL Link to full text

Ellipsometric measurements of plastically deformed copper
M. Mirić, Rebeka Rudolf, Ivan Anžel, B. Hadžić, M. Romčević, J. Trajić, Nebojša Romčević, 2009, published scientific conference contribution

Abstract: Chemically pure copper (99.99) prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm was extremely plastically deformed with the repeated application of equal channel angular pressing. Equal channel angular pressing was applied as an effective technique for producing bulk nanoscaled structures. It is well known that severe plastic deformation of metallic materials often leads to microstructure with ultrafine grains and cross-sections which remain about equal before and after deformation. Optical properties of the sample were studied using spectroscopic ellipsometry in UV-VIS range. The parameters of the sample like copper oxide and surface roughness overlayer were calculated using two-film model together with the Bruggeman effective medium approximation.
Keywords: hydrometallurgical extraction of metals, copper
Published in DKUM: 31.05.2012; Views: 1683; Downloads: 138
URL Link to full text

Charpy toughness and microstructure of vibrated weld metal
Bogdan Pučko, Vladimir Gliha, 2006, original scientific article

Abstract: Vibration during welding can be used to obtain certain changes in mechanical properties of weld metal. Research work on the influence of vibration on the secondary microstructure of welds and hence on the Charpy toughness was performed. Vibration during welding exhibits positive effects on the microstructure constituent formation. Multipass welding was simulated with reheating of the original single pass weld in order to obtain similar microstructure to multipass welds. Microstructures were examined with an optical microscope. Additionally, fractographic examination of the rupture of Charpy specimens was performed. Changes in the microstructure according to vibration were observed which affect toughness of the weld metal. Vibration during welding was rated more effective in the case of reheating the weld metal, which is the case in multipass welding.
Keywords: welding, welded joints, mechanical properties of metals, ferrite, vibration, microstructure, toughness, notched bar testing, weld metal
Published in DKUM: 31.05.2012; Views: 2222; Downloads: 103
URL Link to full text

Search done in 0.18 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica