• Elastomers and Composites
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• v.51 no.1
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• pp.38-42
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• 2016

For improving the heat loss of a refrigerator around door gasket, it is very important to reduce the amount of rubber magnet used, of which thermal conductivity is much higher than the plastics, and enhancing the magnetic properties of rubber magnet itself is crucial for this. In the present study, therefore, a relationship between the optimum conditions of rubber magnet fabrication process and raw material compositions in the ferrite powder/CPE binder compounds was investigated for finding a way to enhance the magnetic properties of rubber magnet. Magnetic attraction forces of a sample rubber magnet was measured as function of distance, and thermal properties of the sample ferrite powder/CPE binder compound were analyzed with TG/DTA thermal analyzer. As a results, a rubber magnet strip with enhanced magnetic properties was expected to be fabricated, of which raw material compound was prepared by compounding with higher ferrite magnetic powder concentration.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.652-658
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• 2000

In many cases, ferrite magnets of ferrite bonded magnets used in inner-rotor type small brushless DC(BLDC) motors do not have rotor core. The magnetization directions of permanent magnets do not have only parallel or radial direction. In this case, the characteristics of magnets are different from cored type ones which have uniform magnetization direction. In this paper, the magnetization directions and intensities of a ferrite magnet and a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of inner-rotor type BLDC motor are analyzed by using the analyzed results. The validity of the method is verified by comparing the analyzed results with measured ones.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.121-129
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• 2008

This paper deals with the design of BLDC motor replacing ferrite magnet with rare earth magnet. Electric machinery system using ferrite magnet motor is already widespread in large numbers. Electrical appliance makers have a tendency to adhere to existing system using ferrite magnet motors because of redesigning the whole system. This paper designs the rare earth magnet motor untouching the external system dimension and motor outer size. To do the design simply, finite element package is used iteratively To reduce the cogging torque effect and magnetic saturation, stator yoke shape and the groove of the end face of yoke are redesigned.

• Resources Recycling
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• v.12 no.6
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• pp.19-25
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• 2003

This experiment was carried out to examine the effect of iron oxide roasting for Sr-ferrite magnet. Chloride content was decreased with raising the 2 nd roasting temperature of iron oxide for ruthner process iron oxide. The optimization temperature for roasting of ruthner process iron oxide was around $800^{\circ}C$ as average particle size 1.5∼1.9 $\mu\textrm{m}$, apparent bulk density 1.4 g/$m\ell$ and chloride content 0.05%. The relation between Br and HcJ by sintering temperature for Sr-ferrite magnet was found to be Br≒-0.258HcJ＋494. In case of having a vibrating disk mill for the ruthner process iron oxide, the magnetic properties were Br 421 mT and HcJ 251 kA/m.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.51-51
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• 1999

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.440-446
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• 1997

This research has been performed for the fabrication of high quality ferrite plastic magnet. The magnetic properties of S $r_{5.9}$F $e_2$ $O_3$ ferrite bonded magnets by injection moulding with a variety of applied magnetic field were investigated. 0.3wt% CaCO3, 0.2wt% $SiO_2$, 0.5wt% $Al_2$ $O_3$and 0.5wt% N $a_2$ $SiO_3$are added in order to improve the magnetic properties of Sr-ferrite plastic magnets during the powder fabrication. For carbon coating on chemical compound specimen, 5wt% polyvinyl alcohol is added, and then calcinated under $N_2$ environment of 12$25^{\circ}C$. The particle size is distributed from 0.9~1.2${\mu}{\textrm}{m}$ which approximates to the single domain. The obtained Sr ferrite powder is well mixed with silane coupling and calcium stearate of 1wt%. Nest, the specimen is pelleted after kneading each of them with polyamidel2 as a binder. When the temperature of injection and mould were 25$0^{\circ}C$ and 8$0^{\circ}C$ respectively at injection pressure of 200kgf/$\textrm{cm}^2$, the degree of orientation was 85.3% under the applied magnetic field of 12kOe. As the results, when the packing density of Sr ferrite powder was 90wt%, the magnetic properties of Sr ferrite bonded magnet were follows : $_{B}$ $H_{c}$=2.41kOe, Br=3.1kG, (BH)$_{max}$=2.21MgOe. Especially, the Sr-ferrite bonded magnet with 10wt% N $d_2$F $e_{14}$B additive were as follows : $_{B}$ $H_{c}$=2.57kOe, Br=3.14kG and (BH)$_{max}$=2.39MGOe.GOe.GOe.GOe.e.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.118-121
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• 1991

The characteristics of magnetizing system considering the anisotropy and the nonlinearity are analyrized using PEM in This paper. The case of magnetizing the ferrite magnet with 12 poles is analyrized. The anisotropy characteristic is considered when ferrite magnet which is widely used as permanent magnet is magnetized. The Nonlinear characteristic of magnetizing yoke aid ferrite is considered because the current is in the saturation region. When the magnetizing current value is over the optimum value, the magnet is magnetized with 24 poles. This is not the case of our expectation. Thus, for the case of our expected magnetizing form, it is the conclusion that the optimum magnetizing current value is selected.

• Journal of the Korean Ceramic Society
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• v.42 no.10 s.281
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• pp.672-677
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• 2005

In this study we prepared the Sr-ferrite powders and magnet by a molten salt method using the (NaCl+KCl) salt mixture. Starting materials of $Fe_{2}$$O_{3}$ and Sr$Co_{3}$ were mixed as the molar ratio of 5.70:1, and 0.08 mol$ \% $ $Al_{2}$$O_{3}$, 0.10 mo1$ \% $ Si$O_{2}$ and 0.12 mo1$ \% $ CaO were added as additives. Sr-ferrite powders synthesized at the reaction temperatures of 800$\∼$1200$ ^{\circ}C $ showed the typical M-type hexagonal ferrite phase, and hexagonal plate-like morphology with uniform distribution of 1$\∼$3 $\mu$m particle size. The bulk density of the sintered Sr-ferrite magnet prepared with powders by the molten salt method showed the maximum density of 4.82 g/$cm^{3}$ at the sintering temperature of 1200$^{\circ}C $. The maxima of remanent flux density (Br, 45 emu/g) and coercive force (iHc, 3.75 kOe) occurred at the sintering temperatures of 1150$ ^{\circ}C$ and 1200$^{\circ}C $.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.942-949
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• 2014

We studied about the rotor design change using a Ferrite ring magnet to reduce material cost in the condition of the same stator core design. However, this design direction has many weak points such as the decrease of BEMF, the low maximum output, the irreversible demagnetization characteristics of a permanent magnet and so on. In order to mitigate such disadvantages, an optimization design of the BLDC motor has been developed by changing each design parameter and by improving the electromagnetic structure. In the proposed water pump SPM BLDC motor using Ferrite magnet, the outer and inner diameter of stator is fixed to the value of the conventional IPM BLDC motor using Nd-Fe-B magnet. The design specification requirements should be satisfied with the same output power and efficiency characteristics in the same dimension. As a result of this study, the design comparison results considering driving performances and material cost are represented. Through the actual experiment with the prototype of the designed motor, the simulations results are verified.

• Proceedings of the Korean Magnestics Society Conference
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• 2017.05a
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• pp.114-114
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• 2017