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Alternative Title: ENHANCING MAGNETIC PROPERTIES OF Nd-Fe-B-type DIE-UPSET MAGNETS BY RF3-DOPING

Abstract: One of the critical issues of recent Nd-Fe-B-type magnet industry is and enhacement of coercivity for high temperature applications such as the traction motors in hybrid and electrical vehicles and wind turbine generators. As an effective means for enhancing the coercivity, grain boundary diffusion process using heavy rare earth salt has been widely investigated. Melt-spun Nd-Fe-B flakes are mixed with RF3 and then hot-pressed and hot-deformed. Rare earth dopant from the doped RF3 substitutes some of Nd In either Nd2Fe14B matrix grain or Nd-rich grain boundary phase or both phases in the flake, thus enhancing coercivity. In this study, Enhancing magnetic properties of Nd-Fe-B-type die-upset magnets by RF3-doping were investigated.

URI: https://repository.pknu.ac.kr:8443/handle/2021.oak/12889
http://pknu.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002235631

Table Of Contents: 목 차
Abstract

1. 서 론

2. 이론적 배경 1
2.1 강자성체의 자기이력곡선 3
2.2 영구자석의 주요 물·특성 5
2.2.1 포화자화 (Saturation magnetization) 5
2.2.2 잔류자속밀도 (Remanence) 5
2.2.3 최대에너지적 (Maximum energy product) 6
2.2.4 유도보자력 (Induction Coercivity) 6
2.2.5 고유보자력 (Intrinsic Coercivity) 6
2.2.6 자기이방성 (Magnetic anisotropy) 7
2.2.7 각형비 (Squareness) 7
2.2.8 큐리온도 (Curie temperature) 8
2.3 Nd-Fe-B계 영구자석 10
2.3.1 Nd-Fe-B계 소결자석 (Sintered magnet) 10
2.3.2 Nd-Fe-B계 본드자석 (Bonded magnet) 11
2.3.3 Nd-Fe-B계 열간 변형자석 (Die-upset magnet) 11
3. 실험방법 13
3.1 합금의 조성 및 제조 13
3.2 열간 압축성형 (Hot-pressing) 15
3.3 열간 변형 (Die-upset) 17
3.4 재료의 미세조직 관찰(SEM) 19
3.5 재료의 자기적 특성 분석(VSM) 19
3.6 재료의 시차열분석 (DTA) 20
3.7 재료의 열분해분석 (TGA) 20

4. 결과 및 고찰 21
4.1 열간 압축성형한 자석의 자기적 특성 21
4.2 열간 변형자석의 자기적 특성 32

5. 결 론 42

참고문헌 43

감사의 글 46

부록 47

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