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Title:Študija parametrov hitrega strjevanja na mikrostrukturo in magnetne lastnosti zlitin iz sistema Nd-Fe-B
Authors:Berložnik, Bojan (Author)
Brunčko, Mihael (Mentor) More about this mentor... New window
Anžel, Ivan (Co-mentor)
Files:.pdf MAG_Berloznik_Bojan_2016.pdf (5,43 MB)
 
Language:Slovenian
Work type:Master's thesis/paper (mb22)
Typology:2.09 - Master's Thesis
Organization:FS - Faculty of Mechanical Engineering
Abstract:Magnetne materiale uporabljamo na številnih področjih kot sestavne dele naprednih tehničnih naprav. Trajni magneti se množično uporabljajo na področjih računalniške tehnike, kot sestavni deli motorjev in generatorjev, v telekomunikacijah, informatiki, merilni tehniki, v akustiki in medicini. Vrhunec razvoja na področju trajnih magnetov predstavljajo magneti iz sistema Nd-Fe-B. To vrsto magnetov odlikujejo visoka koercitivnost, remanenca in maksimalni energijski produkt. Naštete magnetne lastnosti so ob znani kemijski sestavi magnetov odvisne od mikrostrukture, ki pa je pogojena s tehnologijo izdelave Nd-Fe-B zlitine. Sčasoma so klasične postopke litja zamenjale tehnologije hitrega strjevanja. Ugotovljeno je bilo, da počasno strjevanje taline ne vpliva dobro na magnetne lastnosti Nd-Fe-B magnetov. Počasno strjevanje taline omogoči nezaželeno rast zrn. Grobozrnata mikrostruktura zlitin pa ne omogoča uspešnega mletja v droben prah. Dodaten problem pri počasnem strjevanju predstavlja tvorba mehko magnetne alfa-Fe faze. Nasprotno, z hitrim strjevanjem dosežemo manjšo stopnjo mikrosegregacij v zlitini ter pospešimo usmerjeno rast zrn. Tako nastala mikrostruktura je bolj fina, z enakomerno porazdelitvijo usmerjenih zrn. Mehko magnetna alfe-Fe faza se pri dovolj velikih hitrostih ohlajanja ne pojavlja v mikrostrukturi. V magistrskem delu je obravnavana problematika hitrega strjevanja Nd-Fe-B zlitin v centrifugalnem atomizerju. Ugotavljali smo, kako sprememba vrtilne frekvence diska centrifugalnega atomizerja in časa taljenja vplivata na mikrostrukturo lusk Nd-Fe-B zlitin in sintranih Nd-Fe-B magnetov. Raziskava je zajemala izdelavo večjega števila vzorcev Nd-Fe-B zlitine in Nd-Fe-B magnetov, pri različnih proizvodnih parametrih. Bila je opravljena kvantitativna in kvalitativna analiza mikrostrukture vzorcev in magnetov. Izdelanim magnetom so bile dodatno merjene magnetne lastnosti. Raziskava je pokazala da že majhne spremembe parametrov hitrega strjevanja povzročijo pomembne razlike v mikrostrukturi Nd-Fe-B zlitine, Nd-Fe-B magnetov in pripadajočih magnetnih lastnostih. Najboljše magnetne lastnosti so bile izmerjene pri magnetu 4, ki je bil izdelan pri najvišji vrtilni frekvenci diska centrifugalnega atomizerja (f=270 min-1)in ustreznem talilnem času komponent (t=10 min). Slabše magnetne lastnosti so bile izmerjene pri magnetih izdelanih pri nižji vrtilni frekveci diska (f=210 min-1)in prekratkih časih taljenja komponent (t=6 min).
Keywords:Nd-Fe-B magneti, trajni magneti, mikrostruktura, magnetne lastnosti, hitro strjevanje, proizvodni parametri, centrifugalna atomizacija
Year of publishing:2016
Publisher:[B. Berložnik]
Source:Maribor
UDC:621.18:669.018.582(043.2)
COBISS_ID:19785494 Link is opened in a new window
NUK URN:URN:SI:UM:DK:RDNETUPU
Views:1161
Downloads:71
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:English
Title:The study of rapid solidification parameters on the microstructure and magnetic properties of alloys from the Nd-Fe-B system
Abstract:Magnetic materials are used in many areas as components of advanced technical equipment. Permanent magnets are widely used in the fields of computer technology, as integral parts of engines and generators, in telecommunications, informatics, measuring technology, in acoustics and medicine. The highlight of the development in the field of permanent magnets constitutes of magnets from the Nd-Fe-B system. This type of magnets is distinguished by a high coercivity, remanence and maximum energy product. Listed magnetic properties beside the known chemical composition of the magnets depend on the microstructure, which is conditional on the production technology of the Nd-Fe-B alloy. Eventually, the conventional casting processes were replaced by technology of rapid solidification. It was found that the slow solidification of the melt does not have a good effect on the magnetic properties of Nd-Fe-B magnet. Slow solidification of the melt enables undesirable grain growth. Graund granulated microstructure of the alloy does not permit successful grinding to a fine powder. An additional problem in the slow solidification represent the formation of the soft magnetic alfa-Fe phase. On the contrary, the rapid solidification reaches the minimum level of microsegregation in the alloy and thus accelerate oriented growth of grains. The resulting microstructure is finer, a uniform distribution of oriented grains. Soft magnetic alfa-Fe phase at a sufficiently large cooling rate does not appear in the microstructure. The thesis discusses the rapid solidification of Nd-Fe-B alloys in the centrifugal atomizer. We evaluated how the change of frequency rate of the centrifugal atomizer disc and the melting time effect on microstructure of scales of Nd-Fe-B alloys and sintered Nd-Fe-B magnets. The survey covered the production of a larger number of samples of Nd-Fe-B alloys and Nd-Fe-B magnets in a variety of production parameters. A quatitative and qualitative analysis of the microstructure of samples and magnets was carried out. The magnetic properties of manufactured magnets were additionally measured. Research has shown that even small changes in the parameters of rapid solidifications lead to significant differences in the microstructure of Nd-Fe-B alloys, Nd-Fe-B magnets and their magnetic properties. The best magnetic properties were measured in the magnet 4, which was produced at the maximum frequency rate of the centrifugal atomizer disc (f=270 min-1) and in the corresponding melting time of components (t=10 min). Inferior magnetic properties were measured in magnets produced at low speed of the disc (f=210 min-1) and too short melting time of components (t=6 min).
Keywords:Nd-Fe-B magnets, permanent magnets, microstructure, magnetic properties, solidify rapidly, production parameters, centrifugal atomization


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