Cu-Zn-Mg ferrite의 조성성분 및 소결온도에 따른 자기적 특성변화 연구

고재귀,Koh, Jae-Gui 한국재료학회 2003 한국재료학회지 Vol.13 No.6

Small amounts of additives such as mol % 0.13 NiO and mol % 0.01 $CaCO_3$were added to Cu-Zn-Mg ferrites. Basic composition of the Cu-Zn-Mg ferrites was $Cu_{Cu}$X/$Fe_{0.054}$ /$Zn_{0.486}$$Mg_{0.407}$ $Fe_{1.946}$ $O_4$(group A) and $Cu_{0.263}$$Fe_{0.027}$ $Zn_{0.503}$ $Mg_{0.262}$ $Fe_{1.973}$ $O_4$(group B). Specimens were sintered at different temperatures (1010, 1030, $1050^{\circ}C$) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and the magnetic properties such as inductions, coercive forces, and initial permeabilities of the Cu-Zn-Mg ferrites were investigated. The average grain size increased with the increase of sintering temperature. The magnetic properties obtained from the aforementioned Cu-Zn-Mg ferrite specimens were 1,724 gauss for the maximum induction, 1.0 oersted for the coercive force, and 802 for the initial permeability. These magnetic properties indicated that the specimens could be utilized as the core of IFT (intermediate frequency transformer) and antenna in the amplitude modulation.

원료 변화에 따른 Ni-Zn Ferrite의 물리적 특성에 미치는 영향

고재귀,Koh, Jae-Gui 한국재료학회 2006 한국재료학회지 Vol.16 No.9

We studied the physical properties of Ni-Zn ferrites by adding different chemicals such as $SO_4$, Cl, and $NO_3$. Specimens were prepared by the coprecipitation method and sintered at temperatures $950^{\circ}C,\;1,150^{\circ}C,\;and\;1,350^{\circ}C$, respectively. X-ray diffractions showed a spinel structure and the optical microscopy revealed grain size of 0.3 to 0.6 ${\mu}m$. The optimum sintering temperature to obtain fine, sintered microstructure depended on the additive : Cl and $NO_3\;at\;950^{\circ}C\;and\;SO_4\;at\;1,150^{\circ}C$. According to particle size analysis, higher magnetic permeability and magnetization value were observed with Cl and $NO_3\;than\;SO_4$. As sintering temperature was raised from $950^{\circ}C$ to $1,350^{\circ}C$, the average grain diameter, initial permeability and the magnetic moment also increased.

Co₃O₄첨가에 따른 고주파용 Ni-Zn계 ferrite의 물리적 특성 연구

고재귀,Koh, Jae-Gui 한국재료학회 2002 한국재료학회지 Vol.12 No.10

We studied the physical properties of $Co_3$$O_4$-added Ni-Zn ferrite which were sintered at 1050~110$0^{\circ}C$ for 2 hours. X-ray diffraction showed a spinel structure, and optical microscopy showed grain sizes of 5 to 10 $\mu\textrm{m}$. As the sintering temperature was increased from $1050^{\circ}C$ to $1070^{\circ}C$, the initial permeability and magnetic induction increased, and both of the loss factor and the coercive force decreased. The Curie temperatures were about $^234~245{\circ}C$ with added $Co_3$$O_4$. The initial permeability was 350 to 420 and maximum magnetic induction density and coercive force 4870G to 4980G and 0.15 Oe to 0.21 Oe, respectively which were similar to those of Ni-Zn ferrite synthesized in the conventional process. The frequency of specimen was in the range of 1MHz to 300MHz. In the plot of initial permeability vs. frequencies, a $180^{\circ}C$ rotation of the magnetic domain could be perceived in a broad band of microwave before and after the resonance frequency.

ZnO가 Lithium ferrite의 물리적 특성에 미치는 영향에 관한 연구

고재귀(Jae Gui Koh) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.5

Lithium ferrites are prominent in the element of microwave frequency communication core and high frequency memory core because of their low coercivity and the high squareness ratio. This paper reports primarily the development of lithium ferrites with the low coercivity and high squareness ratio. The materials with Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(x=0, 0.01, 0.02, 0.03) have been prepared to investigate the physical properties. The addition of ZnO gave raised maximun induction (Bm) and decreased coercive force (Hc), but the squareness ratio (R = Bm/Br) was decreased. The specimen of squareness ratio R=0.82, coercive force Hc=1.80 Oe was obtained for Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(X=0) sintered at 1050 ℃. Also the sample of squareness ratio R=0.75, coercive force Hc=1.70 Oe for Li_(0.48-0.5x)Bi_(0.02)Ni_(0.04)Zn_xFe_(2.46-0.5x)O₄(X=0) sintered at 1100 ℃ was measured. The Tc was obtained 463 ℃ and the Br of enviromental temperature variation was stable.

Mn - Zn ferrite의 성분 및 소결 온도에 따른 물리적 특성의 향상 연구

고재귀(Jae Gui Koh) 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.4

The basic composition of Mn-Zn ferrite was Mn_(0.631)Zn_(0.316)Fe_(2.053)O₄(specimen A), Mn_(0.584)Zn_(0.312)Fe_(2.104)O₄(specimen B) and Mn_(0.538)Zn_(0.308)Fe_(2.145)O₄(specimen C) with additional 0.1 ㏖% CaCO₃ and 0.04 ㏖% V₂O_5. For high permeability and acceleration of grain growth, CaCO₃ and V₂O_5. was added.<br/> The mixture of the law materials was calcinated at 950℃ for 3 hours and then milled. The compacts of toroidal type were sintered at different temperature(1250 ℃, 1300 ℃, 1350 ℃) for 2 hours in N₂ atmosphere.<br/> The effects of the various raw material composition and sintered temperature on the physical properties of Mn-Zn ferrite have been investigated.<br/> They turned out to be spinel structure by X-ray diffraction and the size of grain from SEM was from 18 ㎛ to 23㎛.<br/> As the sintering temperature was increased from 1250 ℃ to 1350 ℃, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased.<br/> The coercive force and curie temperature were almost the same at each specimen. Their values were about 0.45 Oe and 200 ℃. The frequency of specimen will used in the range from 200 ㎑ to 2 ㎒. The basic composition of Mn_(0.584)Zn_(0.312)Fe_(2.104)O₄ (specimen B) sintered at 1300 ℃ shows the best results at magnetic induction (Br & Bm).

Pr - Fe - B계 희토류 자석의 물리적 특성 향상에 관한 연구

고재귀(Jae Gui Koh),임상희(Sang-Hee Lim) 한국자기학회 1996 韓國磁氣學會誌 Vol.6 No.5

To obtain the Pr-Fe-B ternary system magnets with higher (BH)max, the effect of composition ratio and various heat-treatment temperatures on the magnetic properties of Pr-Fe-B system rare-earth magnets were investigated.<br/> The magnets with various composition of Pr and Fe were heat-treated at 990 ℃, 625 ℃, 585 ℃, 550 ℃ after sintering.<br/> Curie temperature is 310 ℃ and quantitative analysis by SEM, EDX shows that the Pr₂Fe₁₄B, Pr-rich phase consist of Pr~14 at.% and Fe~86 at.%, Pr~58 at.% and Fe~42 at.%, respectively, The coercivity is decreased after heat-treating at 990 ℃ and increased from 5.6 to 6.3 kOe at 625 ℃. The maximum energy product is decreased from 43.4 to 30.3 MGOe after the heat-treating at 990 ℃ but increased from 42.7 to 45.0 MGOe, about 5 %, by heat-treating at 625℃.

고투자율, 저보자력을 갖는 Ni - Zn Ferrite의 개발에 관한 연구

고재귀(Jae Gui Koh) 한국자기학회 1997 韓國磁氣學會誌 Vol.7 No.1

The effects of the various raw material composition and sintered temperature on the physical properties of Ni-Zn ferrite have been investigated.<br/> They turned out to be spinel structure by X-ray diffraction and the size of grain from microscope was from 6 ㎛ to 16 ㎛.<br/> As the sintering temperature was increased from 1030 ℃ to 1070 ℃, the initial permeability and magnetic induction has increased and the both of Q factor and coercive force has decreased.<br/> The coercive force and curie temperature were almost the same at each specimen. Their values were about 0.20 Oe and 220 ℃. The frequency of specimen will used in the range from 400 ㎑ to 20 ㎒. The basic composition of Ni_(0.14)Zn_(0.64)Cu_(0.22)Fe₂O₄ (specimen B) sintered at 1050 ℃ shows the best results at magnetic induction(Br & Bm).

저온소결 온도변화에 따른 Ni-Zn-Cu 페라이트의 자기적 특성 연구

고재귀(Jae Gui Koh) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.6

We have synthesized the low temperature sintered of Ni-Zn-Cu ferrite with nonstoichiometric composition a little deficient in Fe₂O₃ Ni<SUB>0.2</SUB>Cu<SUB>0.2</SUB>Zn<SUB>0.6</SUB>)<SUB>1 + x</SUB>(Fe₂O₃)<SUB>1 ? x</SUB>. For low loss and acceleration of grain growth TiO2 and Li2CO3 was added from 0.25 mol% to 1.0 mol%. The mixture of the law materials was calcinated and milled. The compacts of toroidal type were sintered at different temperature (875 ℃, 900 ℃, 925 ℃, 950 ℃) for 2 hours in air followed by an air cooling. Then, effects of composition and sintering temperatures on the physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, and quality factor of the Ni-Zn-Cu ferrite were investigated. The density of the Ni-Zn-Cu ferrite was 4.85~5.32 g/㎤, resistivity revealed 10?~10¹² Ω-㎝. The magnetic properties obtained from the aforementioned Ni-Zn-Cu ferrite specimens were 1,300 gauss for the maximum induction, 4.5 oersted for the coercive force, 275 for the initial permeability, and 83 for the quality factor. The physical properties indicated that the specimens could be utilized as the core of high frequency range (involved microwave range) communication and deflection yoke of T.V.

Ni-Zn Ferrite의 조성성분 및 소결온도에 따른 물리적 특성의 실험적 연구

고재귀(Jae Gui Koh) 한국자기학회 2006 韓國磁氣學會誌 Vol.16 No.5

The basic composition of Ni-Zn ferrite was (Ni<SUB>0.35</SUB>Cu<SUB>0.2</SUB>Zn<SUB>0.45</SUB>)<SUB>1.02</SUB>(Fe₂O₃)<SUB>0.98</SUB> (group A) and (Ni<SUB>0.4</SUB>Cu<SUB>0.2</SUB>Zn<SUB>0.4</SUB>)<SUB>1.02</SUB>(Fe₂O₃)<SUB>0.98</SUB>(group B) with additional 0.1 ㏖% CaCO₃ and 0.03 ㏖% V₂O?. For high permeability and acceleration of grain growth, CaCO₃ and V₂O? was added. The mixture of the law materials was calcinated at 600 ℃ for 2 hours and then milled. The compacts of toroidal type were sintered at different temperature (1,050 ℃, 1,070 ℃, 1,100 ℃) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, quality factor, and curie temperature of the Ni-Zn ferrite were investigated. The density of the Ni-Zn ferrite was 4.90~5.10 g/㎤, resistivity revealed 108~1012Ω-㎝. The average grain size increased with the increase of sintering temperatures. The magnetic properties obtained from the aforementioned Ni-Zn ferrite specimens were 4,000 gauss for the maximum induction, 0.25 oersted for the coercive force, 2,997 for the initial permeability, 208 for the quality factor, and 202 ℃ for the curie temperature. The physical properties indicated that the specimens could be utilized as the core of microwave communication and high permeability deflection yoke of high permeability.

CuO 대신 Cu 미분말 치환이 NiCuZn Ferrite에 미치는 영향에 관한 연구

김재식(Jae Sik Kim),고재귀(Jae Gui Koh) 한국자기학회 2003 韓國磁氣學會誌 Vol.13 No.1

Diffusion speed of Cu metal fine particle is fast better than CuO, so it will promote grain growth in sintering. In this paper, the influence on substituting Cu fine particle for CuO of NiCuZn ferrite with basic composition (Ni_(0.204)Cu_(0.204)Zn_(0.612)O_(1.02))Fe_(1.98)O_(2.98) has been investigated with varying Cu/CuO ratio. The perfect spinel structure of sintered specimen at 900℃ was confirmed by the analysis of XRD patterns. The best condition was obtained when the ratio of Cu/CuO was 60%, and the permeability was 1100 and Ms was 87 emu/g in this condition. Cu has influenced on grain growth in sintering, substituting Cu fine particle for CuO could lower sintering temperature over the 30℃. After sintering, substituting Cu performed as good as CuO.