• Journal of the Korean Magnetics Society
• /
• v.5 no.1
• /
• pp.15-20
• /
• 1995

We have prepared 20 kinds of Mn-Zn ferrites as content of CaO(0.1 mol%), NiO(0.0~0.60 mol%) and CoO(0.0~0.8 mol%) adding by the coprecipitation method and studied the magnetic properties as content of CaO, NiO and CoO adding. Initial permeability decrease as the content of NiO and CoO adding increases, while Curie tem~ perature increase as the content of NiO and CoO adding increases. $(H_{c})$, $(B_{s})$ and $(W_{h})$ increase as content of NiO adding increases.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2002.03a
• /
• pp.53-57
• /
• 2002

In this paper, we explain new EM(electromagnetic) wave absorber that mixed NC (Natural Ceramics) and Ferrite with NL(Natural Lacquer). At first, a mixed NC and Ferrite(NC : F = (0.1~30)wt% : (99.9~70)wt%) bum at 95$0^{\circ}C$~125$0^{\circ}C$. And then, it is comminuted and injected into NL((NC+F) . NL = (30~80)wt% (70~20)wt%), finally we made Ferrite-NL EM wave absorber. Generally, conventional labor Ferrite covers only 500 MHz to 10 GHz under tolerance limits of 2 to 6 dB in absorption, and Ferrite-NL is over 8 ~ 14 dB. However, NCFerrite-NL huts superior absorption ability. It is over 16 to 19 dB through 500 MHz to 10 GHz.

• Journal of the Korean Magnetics Society
• /
• v.5 no.3
• /
• pp.197-202
• /
• 1995

고주파용 전원의 필요성이 대두되면서 고주파에서 낮은 자기손실을 가진 재료의 개발이 요구되고 있다. Mn-Zn 페라이트의 자기손실은 전기비저항의 증거나 소결시 미세구조의 제어로 줄일 수 있다. 본 연구에서는 연쇄고온합성법(Self-propagation High- temperature Synthesis)에 의해 제조된 $_Mn_{0.72}$Z $n_{0.22}$)$_{0.94}$ (F $e_{2}$ $O_{3}$)$_{1.06}$ 조성의 Mn-Zn페라이트에서 첨가물이 미세구조와 자기적 성질에 미치는 영향에 대해 조사하였다. $SiO_{2}$와 Ca $Co_{3}$의 복합첨가에 의해 미세구조의 미세화와 아울러 낮은 자기손실 특성을 얻을 수 있었다. 그러나 첨가 물의 과다 첨가시에는 비정상입자성장 조직이 나타났으며 자기적 성질이 현저히 저하 하였다. 전기비저항, 자기손실의 주파수 의존 결과에 근거하여 주된 자기손실기구 및 이에 미치는 첨가물 효과에 대해 논하였다.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2036-2037
• /
• 2007

반사형 펄스와전류(Pulsed Eddy Current; PEC) 탐상을 위한 여러 가지 탐촉자를 설계하고, 수치해석 방법을 사용하여 신호특성과 두께변화에 대한 만감도를 조사하였다. 구리와 페라이트를 차폐체로 사용한 결과, 구리로 차폐한 여자코일이 페라이트로 차폐한 센서코일보다 안쪽에 있는 것이 두께변화에 더 민감하였고, 페라이트만으로 차폐한 경우에도 여자코일이 안쪽에 있는 것이 더 민감하다는 것을 알 수 있었다. 한편, 두께가 두꺼워지면 펄스신호의 피크치는 감소하며 피크 발생시간이 변화하는 것을 관찰할 수 있었다.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.165-166
• /
• 2015

본 논문에서는 기존에 각국에서 제정된 인체에 대한 여러 EMI규격을 제시하고, EV 모델 및 패드의 페라이트 배치 구조에 따라 측정 포인트에서 발생하는 EMI의 값을 비교하여 기존 규격에 적합한 페라이트의 배치를 제안한다.

• Korean Journal of Materials Research
• /
• v.1 no.3
• /
• pp.115-124
• /
• 1991

In this study, the relationship between mechanical properties and the effects of second phase in tri-phase steel which was composed of ferrite-martensite-bainite was investigated. In order to obtain different microstructure of ferrite+martensite(DP), ferrite+bainite(F+B), and ferrite+martensite+bainite(TP, different heat treatment has been accomplished. The effects of volume fraction and microstructure of each specimen were studied on tensile property, Charpy impact energy and stretch-flangeability. As the bainite content in triphase steels increased, the tensile strength, and yield strength decreased as well as the reduction of area and strength-uniform elongation increased. However, ferrite-bainite steel had high yield ratio and yield point elongation. The Charpy impact energy of TP and F+B steel was higher than that of DP steel. In addition, the characteristics of hole expanding limit($\lambda$) of TP steel and F+B steel were higher than that of DP steel. These mechanical properties of tri-phase steel have been improved, because bainite could be deformed easily within ferrite matrix. The effect of bainite on ductility in tri-phase steel has been found to be favorable. In this experiment, tri-phase steel contained within 27% bainite volume fraction had good nechanical properties and superior stretch-flangeability.

• Journal of the Korean Magnetics Society
• /
• v.11 no.6
• /
• pp.267-271
• /
• 2001

These experiments were carried out to examine the effects of elemental substitution of Mn and La-Mn on Sr-ferrite. The calcined properties for the Mn and La-Mn substitution were examined, and the sintered magnetic properties were compared with the stoichiometric condition. The magnetic properties of calcined SrM and (La-Mn)$_{0.3}$-SrM composition were as follows, respectively; M$_{s}$ : 61.06 emu/g, $_{i}$H$_{c}$ : 4.45 kOe and M$_{s}$ : 61.06 emu/g, $_{i}$H$_{c}$ : 4.46 kOe. Also, the sintered ferrite magnets of Mn$_{0.3}$-SrM and [(La-Mn)$_{0.3}$-SrM exhibited a similar properties to the stoichiometric composition but the coercivity of (La-Mn)$_{x}$-SrM was decreased rapidly with x=0.5.

• Journal of the Korean Magnetics Society
• /
• v.11 no.6
• /
• pp.256-261
• /
• 2001

These experiments were carried out to examine the effects of element substitution of Zn and La-Zn for Sr-ferrite. The calcined properties of Zn and La-Zn element substitution were examined, and also the sintered magnetic properties were compared with the stoichiometric condition. The magnetization properties of calcined SrM materials is as follows; M$\_$s/ : 61.06 emu/g. Also, the magnetization properties of calcined Zn$\_$0.3/-SrM materials is as follows; M$\_$s/ : 66.90 emu/g. The sintered magnetic properties of (La-Zn)$\_$0.3/-SrM composition is as follows; B$\_$r/ : 4.21 kG, BH$\_$max/: 4.19 MGOe.

• Resources Recycling
• /
• v.11 no.5
• /
• pp.16-20
• /
• 2002

This experiment was carried out to examine the effects of La-Co substitution on Sr-ferrite. The magnetic properties of calcined and sintered materials varied with the substitutional amount of La and Co elements in Sr-ferrite. Anisotropy field and coercivity for Sr ferrite were increased with raising La-Co substitution amounts. The microstructure observation for Sr ferrite substituted by La-Co revealed that La-Co inhabited grain growth during calcination and promoted lateral grain growth during sintering. The relationship between $B_{r}$ and $_{i}$ /$H_{c}$ for La-Co substituted Sr-ferrite was found to be $B_{r}$$≒0.097_{i}$ /$H_{c}$/+4500. In case of $SrFe_{12}$ $O_{19}$, $B_{r} was 4090 G and $_{ i}$$H_{c}$ was 3560 Oe, but $B_{r}$ was 4080 G and and $_{i}$ $H_{c}$ was 4800 Oe for $Sr_{0.7}$ $La_{0.3}$ $Fe_{11.7}$ /$Co_{0.3}$ $O_{19}$.

• Resources Recycling
• /
• v.13 no.6
• /
• pp.31-36
• /
• 2004

This experiment was carried out to examine the effects of morphology on properties of La-Co substituted SrM ferrite. The magnetic properties of calcined and sintered materials were varried with the substitutional amount of La and Co elements in Sr-ferrite. In the substituted SrM ferrite, the atomic fraction x of La is directly related to the mole ratio n of iron oxide and the atomic fraction y of Co by equation x=2ny. The Hcj values of the calcined powder were about 270 kA/m and 240 kA/m with x=0.3 and x=0.2, respectively at stoichiometry, n=6.0. Crystallites of the sintered material were grown with a plate shape, and their size decreased with increasing mole ratios. Such a shape was caused by the initial state of crystallite formed after calcination. In case of x=0.3 and n=6.0, Br was 415 mT and Hcj was 355 kA/m, and in x=0.2 and n=6.0, Br was 410 mT and Hcj was 370 kA/m. The squareness in 2nd quarter of BH curve with x=0.2 was smoothly improved to compared with x=0.3.