Vpliv temperature na magnetne lastnosti Sm2Co17

Zaplotnik, Matej (author), Markoli, Boštjan (mentor)

Namen diplomskega dela je bil ugotoviti vpliv temperature na magnetne lastnosti nizkokoercitivnih magnetov Sm2Co17. Sintrane vzorce in dvostopenjski temperaturni profil obdelave sem pridobil v podjetju Magneti Ljubljana, d. d. Vzorci so bili razdeljeni v sedem serij in so bili obdelani z dvostopenjsko toplotno obdelavo pod različnimi temperaturami. Temperatura se je med posameznimi vzorci dvigovala za 5 °C, tako je temperatura dvostopenjske toplotne obdelave pri vzorcu iz serije 1 znašala 780 °C/800 °C, pri vzorcu iz serije 7 pa 810 °C /830 °C. Vzorci so bili iz sobne temperature 20 °C ogrevani na 780 °C (za serijo 1), kjer so bili zadrževani 1 uro, sledilo je ohlajanje na temperaturo 400 °C s hitrostjo ohlajanja 1 °C/min, nato pa hitro ohlajanje nazaj na 20 °C. Drugi del toplotne obdelave se je začel s segrevanjem z 20 °C na 800 °C (za serijo 1), vzorci so bili tu ponovno zadržani 1 uro in nato ohlajeni na temperaturo 400 °C s hitrostjo ohlajanja 1 °C/min, na koncu pa zopet hitro ohlajeni na 20 °C. Po opravljeni toplotni obdelavi smo na vseh serijah pridobili krivulje razmagnetenja. Na vzorcih iz serije 1 [780 °C/800 °C], serije 4 [795 °C/815 °C] in serije 7 [810 °C/830 °C] so bile opravljene še rentgenska praškovna analiza (XRD), vrstična elektronska mikroskopska analiza (SEM), metalografska analiza in analiza velikosti zrn. Z omenjenimi preiskovalnimi metodami smo poskusili ugotoviti, zakaj se je z višanjem temperature toplotne obdelave, višala koercitivnost magnetov Sm2Co17, katere vrednosti smo razbrali iz krivulj razmagnetenja. Iz rezultatov analiz smo odkrili, da v preiskovanem temperaturnem območju ne nastajajo nove faze, niti se njihov delež ne spreminja, prav tako ostaja ne glede na višino temperature nespremenjena velikost kristalnih zrn.

• Language: Slovenian
• Keywords: koercitivnost, magneti Sm2Co17, vpliv temperature, magnetne lastnosti, sintranje
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2017
• PID: 20.500.12556/RUL-96422
• COBISS.SI-ID: 1699679
• Publication date in RUL: 02.10.2017

Secondary language

• Language: English
• Title: Temperature effect on the magnetic properties of Sm2Co17

Abstract

The theme of the diploma thesis was to found out the temperature effect on magnetic properties of low coercive magnets Sm2Co17. Sintered samples and two-stage temperature profile were obtained in company Magneti Ljubljana d. d. Samples were divided into seven series, which were treated with two-stage heat treatment at different temperatures. The temperature between the individual samples rose by 5 °C, so the temperature of the two-stage treatment in the sample from Serie 1 was 780 °C/800 °C, and 800 °C/820 °C for the sample from Serie 7. The samples were heated from room temperature 20 °C to 780 °C (for Serie 1), where they were kept for 1h, followed by cooling to a temperature of 400 °C, with a cooling rate of 1 °C/min, and then rapid cooled back to 20 °C. The second part of the heat treatment started with heating from 20 °C to 800 °C (for Serie 1), the samples were once again kept at this temperature for 1h and then cooled to a temperature of 400 °C at a cooling rate of 1 °C/min, where they were finally cooled back to 20 °C. After the heat treatment we measured the demagnetization curves on all of the samples. On samples from Series 1 [780 °C/800 °C], Series 4 [795 °C/805 °C] and Series 7 [810 °C/830 °C] we made additional measurements on X-ray powder diffraction aparature (XRD), Scanning electron microscope (SEM), metallographic analysis and grain size analysis. By using these investigative methods, we tried to determine why the coercivity of the Sm2Co17 magnets increased due to the increase in the temperature of the heat treatment profile. From the results of the analyses, we found out that no new phase is obtained in the investigated temperature range, nor does the proportion of phases change and the size of crystalline grains remained unchanged regardless to the temperature level.

• Keywords: coercivity, Sm2Co17 magnets, temperature effect, magnetic properties, sintered samples