• Polymer(Korea)
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• v.26 no.1
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• pp.98-104
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• 2002

This study was investigated to fabricate the isotropic $Nd_2Fe_{14}B$/epoxy bonded magnets with high characteristics paroduced by compression molding. The magnetic characteristics of the bonded magnets were directly proportional to the density of the magnets and were enhanced by using raw $Nd_2Fe_{14}B$ magnetic powders, having the mean particle size of $200{\mu} m$.without additional milling process. The high characteristics of the bonded magnets were achieved at the following conditions: epoxy resin of 2.0 wt%, silane coupling agent of 0.8 wt%, curing agent of 0.7 wt% on the base of magnetic powders, and curing condition of $150^{\circ}C$/3 hrs. The bonded magnets at the optimum conditions indicated the high characteristics such as the density of 6.1 g/㎤, the remanent flux density of 7.1 kG, the maximum energy product of 9.7 MGOe, and the compressive strength of 17 kg/$mm^2$.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.05a
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• pp.72-73
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• 1997

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.109-115
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• 2012

NeFeB anisotropy bonded magnet has proposed a new paradigm of weight reduction of small motors by replacing the conventional ferrite permanent magnets with its high magnetic property of 25 MGOe during last five years. It has also advanced by leaps and bounds in the field of motor industry for automobiles and electric power tools. And it has led a new innovation of fifty percent weight lightening compared to its current motors by correctly focusing on fuel performance improvement through weight lightening that automobile industry chased. There was, however, another price skyrocketing in 2011 after China had announced its export regulation in rare earth materials in July, 2010. And this price change has an extensive impact on the industries that consume rare earth magnets. This environmental change has caused technical challenge to improve the performance by using least amount of rare earth elements in NdFeB anisotropy bonded magnets, and led to make a new technical approach to a new applied field. In this article, we will show how each nation deals with this industrial issue, and introduce development trend and application of anisotropic NdFeB bonded magnets, so-called MAGFINE made by Aichi Steel Corp.

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.86-89
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• 2014

Anisotropic bonded magnet is composed of magnetic powder and organic binder. organic binder in bonded magnet, serves to orientation of the powder. organic binder is composed of polymer resin, lubricant, hardener and coupling agent, etc.in this study, selection of the various components to producing an organic binder and by adjusting the composition ratio and concentrate, apply to bonded magnet for producing an organic binder that suitable for magnetic powder. so evaluation of magnetic properties and mechanical properties, the organic binder ratio and component was confirmed to suitable for bonded magnet.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.86-87
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• 1998

• Proceedings of the Korean Magnestics Society Conference
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• 1992.03a
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• pp.66-67
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• 1992

• Journal of the Korean Magnetics Society
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• v.21 no.4
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• pp.147-150
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• 2011

Since their discovery in the early 1980's, the market for bonded rare earth magnets has shown steady growth. Today these magnets are widely used for our daily life such as computer peripherals, automotive, consumer electronics, and office automation. However, the price increases of rare-earths started from the $2^{nd}$ half of 2010 became even worse in 2011. During $2^{nd}$ quarter of 2011, almost all of rare-earths showed unprecedented vertical price increases, and it brought significant impact to the related industry in terms of the price and supply. This will ask the fundamental change in the policy of the bonded rare earth industry to expand its market share, which has been highly dependent on the replacement of ferrite magnets via relatively higher performance compared to the price at certain applications. In order to achieve the sustainable growth of bonded rare-earth magnets in the future, it needs to change the current paradigm and setup the new business model. This article includes a brief summary of the rare earth price trend and the applications of the rare-earth bonded magnets. The efforts to improve the performance and diversify the applications for future growth have been also presented.

• Proceedings of the Korean Magnestics Society Conference
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• 2012.05a
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• pp.105-106
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• 2012

• Proceedings of the Korean Magnestics Society Conference
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• 2012.11a
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• pp.88-88
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• 2012

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.60-68
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• 1991

In compacting the melt-spun $Nd_{14}Fe_{76}Co_{4}B_{6}$ and $Nd_{10.5}Fe_{79}Co_{2}Zr_{15}B_{7}$ magnetic powders. the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as ${\phi}(g/cm^{2})=5.2~5.6{\times}P^{0.045~0.065}(ton/cm^{2})$. The $Nd_{14}Fe_{76}Co_{4}B_{6}$ alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 nm) than that of $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy and shows the higher coercivity($iH_{c}=14~15kOe$). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over $12~16\;{\AA}$ thick in the Nd-Fe-Co-B alloy while it ranges over $8~12\;{\AA}$ thick in the Nd-Fe-Co-Zr-B alloy.