http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Fe₃B+Nd₂Fe₁₄B spring magnet 분말 압분체의 Exchange Decoupling
한종수(Jong Soo Han),양충진(Choong Jin Yang),박언병(Eon Byung Park) 한국자기학회 2001 韓國磁氣學會誌 Vol.11 No.5
Experimentally it is well known that the magnetic properties significantly deteriorate when nanocomposite bonded magnet are made from nanocomposite ribbon. A decrease in maximum energy product of Fe₃B+Nd₂Fe₁₄B nanocomposite from 14 MGOe in nanocomposite ribbon to 6.5 MGOe in powder compact was found to be general. Thus, the present study is focused on finding out the root of exchange decoupling of Fe₃B+Nd₂Fe₁₄B nanocomposite powder compacts. The exchange decoupling behavior of the powder compact of Fe₃B+Nd₂Fe₁₄B composition was studied by measuring DC demagnetization and isothermal remanent demagnetization curves, which are essential for plotting produced δM curve. From the δM plot the deterioration in the magnetic properties resulted from the fact that the magnetostatic interaction became dominant rather than the exchange interaction in powder compact. It is concluded that the demagnetization behavior governed by the dominant magnetostatic interaction reduced the remanence magnetization, which caused the reduction of maximum energy product of the powder compact. We also found that the elimination of residual stress which is unavoidably accumulated during grinding process enhanced the magnetic properties considerably.
자장중 열처리에 의한 Nd₂Fe₁₄B / Fe₃B 초미세립 복합자성상의 자기특성 향상
박언병(Eon Byeong Park),양충진(Choong Jin Yang) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.2
An externally applied magnetic field during annealing the Nd₂Fe₁₄B/Fe₃B based spring magnet was found to enhance the exchange coupling between the hard and soft magnetic grains. More than 30 % increase in remanence values for melt-spun Nd₄Fe_(73.5)Co₃(Hf_(1-x)-Ga_x)B_(18.5)(x=0, 0.5, 1.0) alloys was resulted from uniform distribution of Fe₃B, α-Fe as well as Nd₂Fe₁₄B, and also from reduced grain size of those phases by 20 %. The result also showed that there is an optimum grain size exhibiting a high coercivity value which will be discussed in terms of previously simulated exchange coupling parameter.
Nd - YAG Pulsed Laser Ablation법으로 제작한 SmCo계 박막의 자기특성
김상원(Sang Won Kim),양충진(Choong Jin Yang) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.1
SmCo films were deposited on Si(100) substrate by a Nd-YAG pulsed laser ablation of the targets of Sm_(100-x)Co_x (73≤x≤93) at the substrate temperature of 600~700 ℃ and the laser beam energy density of Q switching mode or fixed Q mode. The magnetic properties of the films obtained from the Q switching mode exhibited a 4 π Ms of 5200~7700 Gauss, iHc of 190~250 Oe, and 4πMr/4πMs of 0.4~0.74, respectively, while the fixed Q mode gave the magnetic properties of corresponding films of a 4πMr/4πMs=0.32~0.91 and iHc of 430~6290 Oe, respectively. The fixed Q mode gave the better magnetic properties of the SmCo films which seems to be due to a formation of magnetically hard minor phases in droplet of Sm-rich intermetallics. However, the resultant rough surface of the SmCo films is a problem to be solved by a continued study.
Magnetic Hardening of Rapidly Solidified SmFe7+xMx (M=Mo, V, Ti) Compounds
박언병(E. B. Park),최승덕(S. D. Choi),양충진(Choong Jin Yang) 한국자기학회 1994 韓國磁氣學會誌 Vol.4 No.3
Rapidly solidified SmFe_(7+x)M_x (M = Mo, V, Ti) compound were found to crystallize in the Sm(Fe, M)_7 based stable magnetic phase by introducing a second transition element into the Sm-Fe binary system. The Sm(Fe, M)_7 phase exhibits the highest Curie temperature(Tc = 355℃) ever known in the Sm-Fe magnetic systems with a quite high intrinsic coercivity(iHc = 3 ~ 6 kOe). The Sm(Fe, M)_7 phase remains stable even after annealing if once form during the rapid solidification. The primary reason for the high coercive force is due to the fine grain size(2000 ~ 8000 Å) of the magnetic Sm(Fe, M)_7 matrix phase, and the enhanced Curie temperature is attributed to the extended solid-solubility of the additive transition elements in Fe matrix, which leads to volume expansion of the Sm(Fe, M)_7 cell causing an enhanced coupling constant of Fe atoms.
합금조성에 따른 Nd - Fe - Co - B 및 Nd - Fe - Co - Zr - B계 본드자석의 자기특성
최승덕(S. D. Choi),이우영(W. Y. Lee),양충진(Choong Jin Yang) 한국자기학회 1991 韓國磁氣學會誌 Vol.1 No.2
In compacting the melt-spun Nd₁₄Fe_(76)Co₄B_6 and Nd_(10.5)Fe_(79)Co₂Zr_(1.5)B_7 magnetic powders, the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The Nd_(10.5)Fe_(79)Co₂Zr_(1.5)B_7 alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as p (g /㎤)=5.2~5.6×P^(0.045~0.065)(ton/㎠).<br/> The Nd₁₄Fe_(76)Co₄B_6 alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 ㎚) than that of Nd_(10.5)Fe_(79)Co₂Zr_(1.5)B_7 alloy and shows the higher coercivity(iHc=14~15kOe). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over 12~16 Å thick in the Nd-Fe-Co-B alloy while it ranges over 8~12 Å thick in the Nd-Fe-Co-Zr-B alloy.