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1.
APPLYING THE GRAIN-BOUNDARY DIFFUSION PROCESS USING ELECTROPHORETIC DEPOSITION TO SELECTED REGIONS OF A Nd-Fe-B MAGNET
Blaž Goričar, 2014, master's thesis

Abstract: This Master's thesis research is about the localized coercivity enhancement of Nd-Fe-B magnets, which are used in electric motors. Computer simulations show, that when magnets operate at high temperatures, they experience large demagnetizing fields. However, this happens only on specific parts of the body of the magnet. The demagnetization can be prevented by locally enhancing the coercivity only on these specific parts. The goal of this Master’s thesis was to research the localized coercivity enhancement by creating a magnet, where one half would have different magnetic properties compared to the other half. Commercially available Nd-Fe-B magnets were bought from Shin-Etsu, Japan. The magnetic properties of the magnets were measured on two very different devices – the permeameter and the vibrating sample magnetometer. The demagnetization curves were compared. The coercivity of the magnet was improved with the electrophoretic deposition of dysprosium on the surface. The dysprosium then diffused, at high temperature, from the surface to the inside of the magnet along the grain boundaries. The microstructure of the magnet was analysed on the scanning electron microscope, while the content of the elements was quantitatively analysed with the EDS method. The demagnetization curves of both devices were comparable. The grain-boundary diffusion process of dysprosium with the electrophoretic deposition increased the coercivity of the magnet by 25 %, without any significant loss in remanence. The research on the localized grain-boundary diffusion was first done with measurements on the vibrating sample magnetometer and then confirmed with the Hall probe. We discovered that one part of the magnet could have different magnetic properties compared to the other half. There was a clear border between the two.
Keywords: Nd-Fe-B magnet, coercivity, magnetic properties, electrophoretic deposition, grain-boundary diffusion process.
Published: 09.09.2014; Views: 1600; Downloads: 93
.pdf Full text (4,38 MB)

2.
SINTEZA PROCESOV PROIZVODNJE BIODIZLA Z MATEMATIČNIM PROGRAMIRANJEM
Blaž Goričar, 2012, undergraduate thesis

Abstract: Diplomsko delo vsebuje matematični model šestih različnih tehnologij proizvodnje biodizla: homogeno bazično katalizo, homogeno bazično katalizo s predpripravo, homogeno kislinsko katalizo, heterogeno kislinsko katalizo, encimsko katalizo ter superkritični proces. Namen diplomske naloge je ugotoviti, katera proizvodnja biodizla je ekonomsko najbolj ugodna in sprejemljiva. Kot glavno surovino smo odvisno od procesa izbrali ali olje oljne repice ali odpadno rastlinsko olje. Optimiranje smo izvedli v programu GAMS, kjer smo kot glavni kriterij optimiranja določili maksimiranje letnega dobička proizvodnje. Pomembna rezultata pri vsakem procesu sta bila še investicija procesa ter strošek na liter biodizla. Osnovna kapaciteta proizvodnje biodzila je znašala 8 500 ton na leto. Zaradi nihanja cen olja in biodizla na tržišču smo izvedli občutljivostno analizo, kjer smo opazovali vpliv spremembe cene biodizla in olja na letni dobiček. Prav tako smo analizirali vpliv povečanja kapacitete na letni dobiček. Določili smo prag donosnosti, kjer postane vsaka proizvodnja dobičkonosna. Rezultati kažejo, da so vsi procesi proizvodnje biodizla močno odvisni od cene surovin, ki predstavljajo skoraj 90% vseh stroškov. Pri procesih, kjer smo kot surovino lahko izbrali cenejše odpadno rastlinsko olje, smo dobili večji letni dobiček in manjši strošek na liter biodizla. Še posebej dobro se je izkazala heterogena kislinska kataliza. Ugotovili smo, da encimska kataliza ni ekonomsko sprejemljiva zaradi visoke cene encimov. Homogena bazična kataliza, ki je najpogosteje uporabljena v industriji, se je izkazala za dobičkonosno pri dovolj veliki kapaciteti proizvodnje.
Keywords: biodizel, transesterifikacija, esterifikacija, olje oljne repice, odpadno rastlinsko olje, letni dobiček.
Published: 11.09.2012; Views: 2362; Downloads: 281
.pdf Full text (3,81 MB)

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