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기록매체용 Iron - nitride의 합성 및 자기특성
오영우(Y. W. Oh),김문섭(M. S. Kim) 한국자기학회 1992 韓國磁氣學會誌 Vol.2 No.3
Iron nitride Fe₄N by partial substitution of nitrogen by carbon was prepared by nitriding the iron oxalate whose thermal decomposition gives a carburating atmosphere. Iron oxalates, the precursors, were prepared by precipitation and co-precipitation. The size and shape of the carbonitride particles could be controlled by modifying the conditions of preparation of the oxalate precursor. From the results of electron micrographs, it is clear that the Fe₄N pigment particle maintains the original shape(needle shape) of the starting materials and that it consists of fine unit particles which link together to form a stereo-network structure.<br/> An investigation of the Fe^Ⅱ₃ Fe^Ⅰ_(1-x) Sn_xN_(1-y)Cy. solid solution has shown that Sn plays the role of a growth inhibitor of the elementary microcrystallites of the iron carbonitride.<br/> The coercive force and saturation magnetization of iron carbonitride obtained from co-precipitated iron oxalate were 500 Oe and 120 emu/g, respectively.
준안정상 Bi2SiO5의 합성과 Ba-Ferrite에의 첨가 효과
오영우 ( Y W Oh ),안종견 ( J K Ahn ),정상훈 ( S H Chung ),박경호 ( K H Park ),김능호 ( N H Kim ) 경남대학교 신소재연구소 2012 신소재연구 Vol.24 No.-
화학식 BaFe12O19인 M(Magnetoplumbite) 형 Ba-ferrite는 가격과 성능의 측면에서 자기기록매체, 전자기기의 부품소자, 자성유체 등의 분야에서 폭 넓게 사용되는 자성재료이다. 일반적인 고상 반응법으로 ba-ferrite를 제조할 때 특성 증진을 위하여 적정량의 첨가제가 필요한데, 본 실험에서는 첨가제로 상용의 SiO2, Bi2O3 및 용융염법으로 자체 합성한 준안정상의 Bi2SiO5를 첨가하여 특성을 분석하였다. NaCl-KCl의 공정 조성(용융온도 645℃)과 BaCO3, Fe2O3를 혼합하고 650℃에서 열처리한 후 수세, 건조시킨 시편은, 단상의 Bi2SiO5임을 XRD 분석 결과로 확인하였으며, BaCO3-5.5Fe2O3의 혼합물에 Bi2SiO5를 첨가하여 열처리한 시편은 SiO2와 Bi2O3를 각각 단독으로 첨가한 시편에 비하여 밀도, 입자의 크기, 자기적 성질 등의 특성이 우수하였다. Ba-hexaferrite, the M(magnetoplumbite)-type magnetic materials having the chemical formula of BaFe12O19 is widely used in the field of magnetic recording media, electronic devices and electromagnetic shieling from the cost and performance point of view. And metastable Bi2SiO5 has been applied as a promising catalyst. The investigations performed on the Fe2O3 and BaCO3 mixture added SiO2, Bi2O3 and metastable Bi2SiO5 synthesized by NaCl-KCl molten salts method. The X-ray diffraction analysis revealed the presence of hexagonal BaFe12O19 and rhombohedral Fe2O3 phases in examined samples. Pure powders were synthesized by molten salt method in NaCl-KCl flux using Bi2O3 and SiO2 as raw materials at 650℃ for 2 hrs., which was lower than that of conventional solid state reaction, 750℃. Addition of metastable Bi2SiO5 in the BaCO3- Fe2O3 mixture was more effective compare with individual addition of SiO2 and Bi2O3. The coercive force(Hc) of studied specimen has a value about 3000 Oe(24 kA/m).
자심재료 특성에 따른 전력선 통신용 비접촉식 커플러의 특성
변우봉(W. B. Byun),이준희(J. H. Lee),김종령(J. R. Kim),정원채(W. C. Jung),김현식(H. S. Kim),오영우(Y. W. Oh),곽귀일(K. I. Gwak),주성호(S. H. Ju) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.4
비정질 합금재료와 페라이트를 사용하여 비 접촉식 커플러를 제조하여 각각의 재료가 적용가능한 범위를 규명하고자 하였다. 비정질 합금재료에 비해 페라이트는 안정적인 특성을 발휘하는 주파수 대역이 좁으며, 낮은 포화자속밀도로 인해 내전류 특성이 떨어졌다. 즉 페라이트는 20 ㎒ 이하의 주파수 대역과 비정질 재료가 적용되는 선로보다 유입전류가 낮은 전력선에 적용 가능할 것으로 보인다.
Mill Scale을 이용한 M형 Ferrite의 합성
오영우(Y. W. Oh) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.4
M type hexa-ferrites were prepared by means of a solid state reaction using mill scale, Fe₂O₃, and the mixture of mill scale and Fe₂O₃. The mixture of powders were calcined at 1150 ℃ for 2 hrs. and sintered at 1250 ℃ for 2 hrs. with varing the mole ratio of Fe₂O₃/BaCO₃ by 5.2~6.0. And the magnetic properties and morphologies of Ba-ferrites with impurities such as SiO₂, Al₂O₃, MgO, CaO and Na₂O in the mill scale were investigated. The magnetic properties were worsened by the addition of Na₂O because of non-reacted iron oxide and intermediate compound of BaFe₂O₄, but they were improved apparently by the addition of SiO₂ and Al₂O₃ in the composition of BaOㆍ5.6Fe₂O₃. Moreover, Ms decreased but B_H_C increased through the addition of Al₂O₃ in Ba-ferrite. (BH)max of sintered BM(BaCO₃, mill scale mixture) and BFM(BaCO₃, Fe₂O₃ and mill scale mixture) were 0.86 and 1.04 MGOe, respectively, and the magnetic properties were changed around 440 ℃.