http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
환원/확산 공정에 의한 고성능 Nd-Fe-B 자성분말의 제조
김동수,진춘강,백연경,최철진,Kim, Dongsoo,Chen, Chunqiang,Baek, Younkyoung,Choi, Chuljin 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.3
A novel route to prepare Nd-Fe-B magnetic particles by utilizing both spray drying and reduction/diffusion processes was investigated in this study. Precursors were prepared by spray drying method using the aqueous solutions containing Nd salt, Fe salt and boric acid with stoichiometric ratios. Precursor particles could be obtained with various sizes from 2 to $10{\mu}m$ by controlling concentrations of the solutions and the average size of $2{\mu}m$ of precursors were selected for further steps. After heat treatment of precursors in air, Nd and Fe oxides were formed through desalting procedure, followed by reduction processes in Hydrogen ($H_2$) atmosphere and with Calcium (Ca) granules in Argon (Ar) successively. Moreover, diffusion between Nd and Fe occurred during Ca reduction and $Nd_2Fe_{14}B$ particles were formed. With Ca amount added to particles after $H_2$ reduction, intrinsic coercivity was changed from 1 to 10 kOe. In order to remove and leach CaO and residual Ca, de-ionized water and dilute acid were used. Acidic solutions were more effective to eliminate impurities, but Fe and Nd were dissolved out from the particles. Finally, $Nd_2Fe_{14}B$ magnetic particles were synthesized after washing in de-ionized water with a mean size of $2{\mu}m$ and their maximum energy product showed 9.23 MGOe.
마이크로웨이브 졸-겔법을 응용한 극저온 자기냉매용 HoN 분말 합성 및 자기열량효과
안종빈 ( Jong Bin Ahn ),김동수 ( Dongsoo Kim ),윤석영 ( Seog Young Yoon ),최철진 ( Chuljin Choi ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.4
Rare-earth (RE) mono-nitrides can be used as magnetocaloric materials for the magnetic refrigerant for liquefying hydrogen. In this study, holmium nitride (HoN) particles were prepared by sol-gel method with microwave irradiation. HoN particles were successfully synthesized by 2-step heat treatment in N2 atmosphere form gel-type intermediate by microwave irradiation. X-ray diffraction patterns of the synthesized HoN particles exhibited the six sharp peaks in good agreement with each plane of crystallographic structure of HoN. Especially, the synthesized HoN particles reveal a high magnetic entropy change (△Sm) of 36.6 J/kgK in applied field of 5T at 14.2 K which is comparable with those of rare earth mono-nitrides by carbothermic reduction method or plasma arc discharge technique.