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기계적 분쇄한 Nd - Fe - B 합금의 다이업셋과 열처리가 자기적 특성에 미치는 영향
정원용(W. J. Jeung),박정덕(J. D. Park),곽창섭(C. S. Kwak),양현수(H. S. Yang) 한국자기학회 1994 韓國磁氣學會誌 Vol.4 No.3
The effect of die upset and heat treatment on the magnetic properties of mechanically ground Nd_(16)Fe_(78)B_6 alloys has been studied. Although stripe domain patterns parallel to the compression direction were observed after die upset, it was found that crystallographic c-axes of a specimen were not completely aligned along the compression direction, which resulted in the decrease of Br. The average grain size of a die-upset specimen annealed for 5 hours at 1000℃ was about 20 ㎛, resulting in reduced values of Br and iHc. The maximum magnetic properties(Br=7. 8 kG and iHc = 14 kOe) were obtained from the magnet die-upset at 750℃ using the alloy powder ground for 13 hours.
전기 도금된 CoFeNi계 박막의 결정크기와 방향성이 자기특성에 미치는 영향
정원용(Won Young Jeung),김현경(Hyun Kyung Kim),박창빈(Chang Bean Park) 한국자기학회 2006 韓國磁氣學會誌 Vol.16 No.5
CoFeNi alloys are some of the most studied soft magnetic materials because of their superial properties over FeNi alloys as write head core materials in HDD and MEMS. We studied the effect of magnetic property according to size and orientation of crystal for electroplated Co-Fe-Ni alloys. In case of heat treated ternary alloy, it affect the change of crystal size and structure. In this study, it intends to improve the magnetic properties of CoFeNi thin film by heat treatment. Minimized coercivity and increased magnetization are due to heat treatment from 300 ℃ to 400 ℃. As a bcc phase formation, it grow to amount of magnetization.
이방성 Sr - 페라이트 / 레진본드 영구자석에서 Sr - 페라이트 자성분말의 방향성
정원용(W. Y. Jeung),조태식(T. S. Cho),문탁진(T. J. Moon) 한국자기학회 1994 韓國磁氣學會誌 Vol.4 No.3
The alignment of Sr-ferrite magnetic powders, which is usually related to the fluidity and the applied magnetic field, is investicated in the anisotropic Sr-ferrite /resin-bonded permanent magnets. The magnetic powder alignment is observed to increase with the applied magnetic field and the fluidity which is a function of molding temperature and powder packing ratio. The rest magnetic powder alignment is achieved at the following conditions; Sr-ferrite packing ratio of 56vol%, apparent viscosity of about 3000 poise in 1000sec-¹ shear rate, and applied magnetic field of about 5kOe. The degree of preferred orientation of the magnetic powders in the field direction, as determined by the dc hysterisis graphs, is 84~85%(0.84~0.85). This result is in agreement with the value of 0.85 obtained by the X-ray experiments in the 2θ range of 23~40^0. The best magnetic properties obtained are; 2.2kG of remanent flux density, 2.2MGOe of maximum energy product.
전기도금 시 외부자기장이 CoPtP 합금의 자기 특성에 미치는 영향
정원용(W. Y. Jeung),박호동(H. D. Park) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.5
We have investigated the effects of an external magnetic field on the growth direction and the grain size of electrochemically prepared CoPtP alloys. Electrodeposited CoPtP alloys were synthesized by appling an external magnetic field with 0 to 1 T to the perpendicular direction of the films. In the electrodeposited CoPtP alloys without external magnetic field, the growth direction of the alloys was mixed by fcc (111) and hcp (002), but only hcp (002) was observed in the alloys with 1 T external magnetic field. CoPtP alloys were grown as the columnar growth and the grain size increases with growing the alloys. With appling an external field, the grain size of the alloys was controlled less than 20 ㎚ which is smaller than single domain of Co, and the easy axis of alloys, hcp (002) direction, was grown perpendicular to the films up to 200 ㎚. We could obtain the optimal thickness of the alloys and electrodeposition condition from the above results. Coercivity and squareness of CoPtP alloys taken out-of-plane are 6.1 kOe and 0.9, respectively. The magnetic properties of CoPtP alloys were measured by VSM, and the microstructural characterization and crystalline orientation measurement of the alloys were carried out by TEM and XRD.