• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.898-901
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• 2006

In this paper, effect of ceramic processing was investigated on the magnetic properties of low loss Mn-Zn ferrite. High frequency characteristics, high saturated magnetic flux density and high magnetic permeability and low magnetism loss are required for the development of Mn-Zn ferrite, which is parts in the communication. therefore, in order to improve Mn-Zn ferrite with a high frequency , it is important to have a minimal change of particles and to control the eddy current loss caused by high resistance of the stratum of particles and to reduce the hysteresis loss by uniform change of detailed structure. In this paper, we added $V_2O_5\;and\;CaCo_3$ to Mn-Zn Ferrite to achieve a high efficiency, low loss core material. The compositions are MnO : ZnO : $Fe_2O_3$ = 21 : 10 : 69 mol%. They were sintered at $1250^{\circ}C$ for Three hours. Initial permeability was measured at 0.1MHz. At 50mT, Power loss was measured by temperature changing at 100kHz.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.34-34
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• 1994

• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.289-295
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• 1997

Effect of ceramic processing was investigated on the microstructure and electronic properties of low loss Mn-Zn ferrite. Addition of CaO and SiO2 to calcined powder rather than to raw materials mixtured resulted in finer-grained microstructure. Higher oxygen pressure during sintering caused microstructural inhomogeneity and the increase in power loss and disaccommodation factor. Relatively low power loss was found for sintering up to 130$0^{\circ}C$ from powders calcined at high temperature and milled shortly. It was caused by slow densification rate and normal grain growth up to 130$0^{\circ}C$. Calcination at low temperature and prolonged milling enhanced den-sification, which gave a fine grained microstructure and low powder loss at sintering temperture below 120$0^{\circ}C$. Sintering temperature above 125$0^{\circ}C$, however, showed abnormal grain growth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.652-655
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• 2001

Power transformers are increasingly becoming more significant in the advancement of electronic equipment. A high-performance, low-cost core material is necessary in order th come up with power transformers in the smallest and lightest scale possible and with low power requirements. In this study, we added V$_2$O$_{5}$ and CaCo$_3$to Mn-Zn ferrite to produce a high-performance low-cost core material. The compositions used were MnO : ZnO : Fe$_2$O$_3$= 37 : 11 : 52 mol%. The materials were sintered at 125$0^{\circ}C$ for three hours. Initial permeability was measured at 0.1MHz. At 200mT, power loss was measured by changing the temperature at 25KHz, 50KHz, 100KHz. When we added 0.lwt% and 0.1%wt% of V$_2$O$_{5}$와 CaCo$_3$, respectively we obtained 405 405KW/㎥ at 200mT, 100KHz, 6$0^{\circ}C$. We tan reduce eddy current loss as a primary loss of high frequency by adding a small amount of V$_2$O$_{5}$와 CaCo$_3$. This reduces power loss in the power transformersormers

• Journal of the Korean Magnetics Society
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• v.9 no.3
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• pp.149-153
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• 1999

Frequency and temperature dependence of magnetic loss has been investigated in Mn-Zn ferrites containing the sesistive temary compounds of $SiO_2-CaO-V_2O_5$. The Mn-Zn ferrite with the composition of $MnO:ZnO:Fe_2O_3=36:11:53$(by mol %) are prepared by self-propagating high-temperature synthesis. From the results of frequency dependence of core loss, it has been found that the hysteresis loss is dominant at low frequency and the eddy current loss becomes more dominant as the frequency increases. With the addition of resistive compound, the frequency dependence of core loss, it has been found that the hysteresis loss is dominant at low frequency and the eddy current loss becomes more dominant as the frequency increases. With the addition of resistive compound, the frequency region where the hysteresis loss is dominant becomes wide. The core-loss minimum occurs at about 4$0^{\circ}C$ in the specimens with the additive because of the reduction in eddy current loss.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.146-152
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• 2003

The waste ferrites from magnetic core manufacturing process were used to $CO_2$gas decomposition to avoid the greenhouse effects. The waste ferrites are the mixed powder of Ni-Zn and Mn-Zn ferrites core. In the reduction of ferrites by 5% $H_2/Ar$ mixed gas, the weight loss of ferrites was about 14~16wt%. After the$CO_2$gas decomposition reaction, the weight of the reduced ferrites was increased up to 11wt%.$CO_2$gas was decomposed by oxidation of Fe and FeO in reduced compound and the phase of the waste ferrite was changed to spinel structure. A new technique capable of$CO_2$decomposition as low cost process through utilizing waste ferrite was development.

• Journal of the Korean Ceramic Society
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• v.32 no.9
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• pp.1033-1039
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• 1995

The current experiment has quantitatively investigated the effect of the content of CaO and SiO2 on the microstructure, density, electrical resistivity, power loss and initial permeability of manganese zinc ferrites. The density increased initially with CaO and SiO2 content and the further addition showed an adverse effect. The excess addition of CaO and SiO2 developed a discontinuous grain growth with numerous pores inside grains and lowered the electrical resistivity. The initial permeability decreased with increasing the content of SiO2. The samples with relatively low power loss showed that half of the total loss at 10$0^{\circ}C$, 100 kHz and 2000 Gauss was due to the eddy current loss.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.561-568
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• 1997

The effects of sintering temperature and oxygen partial pressure on the electromagnetic properties of Mn-Zn ferrites were investigated. The grain increased with increasing temperature. The power loss at 100 kHz was decreased, while the power loss at 500 kHz was increased as the grain size increased with sintering temperature. Sintering with low oxygen partial pressure at 115$0^{\circ}C$ resulted in high density and initial permeability, and decreased the power loss at 100 kHz and 500 kHz. The oxygen partial pressure lower than 10-2 atm. during heating, significantly suppressed the hysteresis loss. However, the oxygen activity did not affect the grain size of sintered cores.

• Resources Recycling
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• v.11 no.5
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• pp.30-33
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• 2002

Recently in the progress of electronic equipment, power transformer was considered an important part. To make power transformer with miniaturization, lightening, low Power, we need a high efficiency core material. In this paper, we added $V_2$$O_{5}$ and $CaCo_3$ to Mn-Zn Ferrite to make a high efficiency, low loss core material. The compositions are MnO : ZnO : $Fe_2$$O_3$=37 : 11 : 52 mol%. They were sintered at 1250 for Three hours. Initial permeability was measured at 0.1 MHz. At 200 mT, Power loss was measured by temperature changing at 25 KHz, 50 KHz, 100 KHz. When we added $V_2$$O_{5}$ and $CaCo_3$, 0.08 wt%, 0.05 wt% respectively, we get 415 ㎾/㎥ at 200 mT, 100 KHz, $60^{\circ}C$. We can reduce eddy current loss as a main loss of high frequency by addition of a little mount of $V_2$$O_{5}$ $CaCo_3$. So we can decrease the power transformer's power loss.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1055-1060
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• 1998

The effects of particle size distribution have been investigated on the high frequency low loss Mn-Zn fer-rites. The particle size distribution was controlled by milling time. Zirconia ball and engineering plastic jar were employed to avoid iron contamination from the milling media. As increasing the milling time BET value was increased from 0.55 to 3.21m2/g and mean particle size was decreased from 2.1 $\mu\textrm{m}$ to 1.0$\mu\textrm{m}$ The large specific surface area of initial powder resulted in the high density of sintered core. However starting powders with high BET lead to inhomogeneous grain growth as well as poor electromagnetic pro-perties at sintering temperature above 1300$^{\circ}C$.