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Fe73.5Cu₁Nb₃Si15.5B7 나노 결정립 합금 분말 코아의 자기적 특성
노태환(T. H. Noh),최혁열(H. Y. Choi),안상재(S. J. Ahn) 한국자기학회 2004 韓國磁氣學會誌 Vol.14 No.1
The annealing-temperature dependence of magnetic properties in compressed powder cores being composed of ball-milled Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 alloy powders (size : 250~850 ㎛) and 5 wt% of ceramic insulators has been investigated. When annealed at 550 ℃ for 1 h and so transformed to α-Fe phase nanocrystalline structure with the grain size of 11 ㎚ (electrical resistivity : 110 μΩ·㎝), the highest effective permeability of 125 and quality factor of 53 were obtained, and the permeability persisted up to about 500 ㎑. Further the core loss measured at the frequency of 50 ㎑ and the induction amplitude of 0.1 T was very low (230 ㎽/㎤). However the dc bias characteristics was not satisfactory as compared to that of conventional powder core materials(MPP, Sendust etc.). The inferior dc bias property of Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 alloy powder cores was attributed to the fact that the size of powder was too large for obtaining the same permeability with that of conventional materials.
FeCuNbSiB 나노결정립 합금 분말코아의 자기적 특성에 미치는 절연체의 영향
노태환(T. H. Noh),최혁열(H. Y. Choi) 한국자기학회 2004 韓國磁氣學會誌 Vol.14 No.5
The variation of magnetic properties with insulating materials(glass frits, talc and polyamide) in compressed powder cores composed of Fe_(73.5)Cu₁Nb₃Si_(15.5)B_7 nanocrystalline alloy powders(size : 250~850 ㎛) and 3 wt% insulators has been investigated. Larger permeability was obtained at the frequency lower than 300~400 ㎑ for the powder cores including ceramic insulators(glass frits and talc) as compared to the cores with polyamide, while at higher frequency than 1 ㎒ the permeability of the former cores decreased rapidly. Further the cores with ceramic insulators showed larger core loss and smaller peak quality factor attained at lower frequency. On the contrary, the powder cores with polyamide exhibited high stability of permeabilities up to several ㎒ and superior core-loss and quality-factor properties. Moreover the de bias property was better in the wide field range for the cores having polyamide. The enhanced magnetic properties of polyamide-added cores were attributed to the more sufficient electrical insulation between magnetic particles, where the higher insulation state was considered to be obtained from the larger volume fraction of polyamide in the powder cores.
가스 분무법으로 제조된 NixFe100-x(x=40~50) 퍼멀로이 분말 및 압분 코아의 자기적 특성
노태환(T. H. Noh),김구현(G. H. Kim),최광보(G. B. Choi),김광윤(K. Y. Kim) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.6
We investigated the magnetic properties of High Flux-type Ni_xFe_(100-x)(x=40~50, wt.%) permalloy powders and dust cores. The powder was prepared by conventional gas atomization in mass production scale. At the composition of Ni_(45)Fe_(55), saturation magnetization was maximum. In case of lower Ni content than X=45, the Ms decreased largely with the decrease in Ni content, which is due to the invar effect. The permeability of compressed powder cores increased with the decrease in Ni content, which was considered to be due to the decrease in the magnetostriction. In addition, the dust core with Ni=45% showed the lowest core loss because of the increase in electrical resistivity leading to the low eddy current loss. From the better frequency dependence of permeability, larger Q value and superior DC bias characteristics of Ni=45 % than those of Ni=50% core, it was confirmed that the 45%Ni-55%Fe powder alloy was better material for the dust core than commercial High Flux core materials.
철계 비정질 합금 분말코아의 자기적 특성에 미치는 분말 제조방식의 영향
노태환(T. H. Noh),최혁열(H. Y. Choi) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.3
In the fabrication process of Fe-based amorphous alloy powder cores by pulverization of the melt-spun ribbons and cold compaction, the effects of powder preparation method on the magnetic & electric properties, powder shapes and microstructure of cores have been investigated. The powder cores made by using rotor mill showed low effective permeability as compared to the cores prepared by ball milling. However the frequency dependence and quality factor properties were superior in the case of rotor-milling. Further the powders prepared by rotor mill had homogeneous and round shapes through strong shearing in the sieve ring, while the ball milled powders were inhomogeneous and relatively small. The lower permeability of the powder cores fabricated with rotor mill was considered to be due to the high internal stress occurred by very intensive shearing. Moreover the powder cores produced by rotor-milling showed lower core loss and good frequency dependence of effective permeability possibly due to the higher electrical insulation between magnetic particles. The dc bias property of the powder cores made by rotor-milling was better than the one by ballmilling.
이용호(Y. H. Lee),신용돌(Y. D. Shin),노태환(T. H. Noh),강일구(I. K. Kang) 한국자기학회 1992 韓國磁氣學會誌 Vol.2 No.3
Annealing effects on the permeability aftereffect (disaccommodation) of liquid quenched single strip Fe_(73.5)Cu₁Nb₃Si_(16)B_(6.5) alloys were investigated with pulse method. The initial susceptibility X. B_(10) (the flux density at 10 Oe) and disaccommodation intensity D (D = [X(1s)-X(64s)]/X(1s). where X(1s) and X(64s) are the susceptibility of 1 and 64 s of rest time after A. C. demagnetization) were about 800, 0.8 T and 16 %, respectively. The soft magnetic properties were improved with isothermal annealing for 1 hour at 300~600 ℃. X. B_(10) and D at 570℃ of optimum annealing temperature were 15000. 1.2 T and 1.1 %. respectively. The origin of the change of characteristics were examined with fine crystalline structure and magnetostriction.
이용호(Y.H.Lee),이연숙(Y.S.Lee),신용돌(Y.D.Shin),문기원(K.W.Moon),노태환(T.H.Noh),김희중(H.J.Kim),강일구(I.K.Kang) 한국자기학회 1991 韓國磁氣學會誌 Vol.1 No.1
A measurement system for magnetic anisotropy was built. The torque acting on the disc or sperical samples placed in uniform magnetic field was detected with a capacitive transducer which is connected with a transformer ratio-arm bridge. The output of the bridge was amplified with a lock-in amplifier. The cubic anisotropy constant for (100) of 3% Si-Fe was 3.3×10⁴ J/㎥. The calibration for the system was carried out with the shape anisotropy of a thin Ni wire.